Hempcrete

Bach-Mühle-Fuchs

Hempcrete Open Data, Upload, Scan, Repro, Online, PDF, Download Version 09.08.2022

Keywords: Hempcrete, Hemplime, hemp-lime, Hanfbeton, Hanfkalk, Stampfbeton, Verbundwerkstoff, Bindemittel, Kalk, Schäben, Hanfschäben, Alternative building material, hemp absorbs CO2, Nettonull, Baubiologie

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Eine Aussenmauer wird mit Hanf bausteinen wdrmeisoliert.

Die holzernen Hanfschdben in den Kalksandsteinen haben hervorragende Diimmeigenschaften und speichern grosse Menge an COz. Coverfoto von Keysfone/Biosphoto/ Pascal 6reboval

Heftreihe KREISLAUFWIRTSCHAFT Nr.2

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troh und Hanf als sogenannte kultivierte Baumdterialien waren bis vor Kurzem sehr alternativ anmutende Nischenprodukte. Das sind sie noch heute - doch aktuelle Beispiele zeigen ihr grosses Potenzial. Hanf und Stroh sind klimaneutral und speichern viel biogenes CO2.

Wandelemente aus Strohballen oder Hanffliesen zum Dd,mmen ktinnen nach dem Rtickbau eines Hauses wieder auf dem Feld verteilt werden und kehren so in den Naturkreislauf zurtick. Bei Hanfkalksteinen sind die Mriglichkeiten eingeschr6nkt; geschreddert ktinnen sie als Komposit oder Auffiillmaterial wiederverwendet werden.

Es stellt sich eines Tages also - wie bei anderen Kompositmaterialien wie Ziegeln - das Problem der Entsorgung.

Fiir eine stringent umgesetzte biogene Kreislaufwirtschaft mtissen jedoch tiber die Okologie hinaus Naturprodukte ganzheitlich mit anderen Wirtschaftszweigen verbunden werden. Sie ktinnten zrrm Beispiel Einkommensquellen in der Landwirtschaft generieren und von der liingst tib erstrapazierten Milchwirts chaft we gftihren.

So lassen sich Methan in der Luft und Nitrate im Boden reduzieren. Das wirft Fragen nach der Infrastruktur auf, die ntitig ist, um entsprechende Landwirtschaftszweige zu etablieren, und auch nach den landschaftlichen Verdnderungen.

Stroh ist ein Nebenprodukt aus der Getreideernte im Flachland, Hanf wiichst dagegen auch in Bergregionen bis zu 1900 m ti. M. Die gesellschaftlichen und landschaftlichen Zusammenhdnge ftihren somit weit iiber die architektonische Gestaltung hinaus.

Danielle Fischer, Redaktorin Architektur

Peter Settz,

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Bearbeitung der Grossslrohballen mit der Motorsense beim Ausstellungsgebiiude des Gartenbauunternehmens Gartist in Bubikon. Die Strohballen selbst tragen hier die Gebdudelast.

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Gold vom Acker Haus und Klima Peter Seitz Das uralte Baumaterial Stroh weist sehr gute

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Ddmmeigenschaften auf - bei dusserst geringem Energieaufwand in der Herstellung und problemlosem Rrickbau. Gute Argumente frir heutige Bauten.

26 Alternafive: Hanf Danielle Fischer Am IVIonViso

Institut im Piemont forscht Tobias Luthe an Baustoffen mit Hanf. Fr.ir eine breitere Nutzung sollen seine Eigenschaften in zeitgenossische Losungen ribersetzt werden.

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fur F1aus und Klilna Es heisst, Rumpelstilzchen konnte Stroh zu Gold spinnen.

Dabei weist Stroh bereits in seiner Reinform Eigenschaften auf, die auf dem Bau Gold wert sind: hervorragende Ddmmwerte bei geringstem Energieaufwand in der Herstellung.

Text: Peter Seitz

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in diese Richtung - <Bioliq> be, zeichnet das Verfahren, das allein aus der in DeutschIand erzeugten Strohmenge Treibstoff frir mehrere I\{il}ionen Autos erzeugen kcinnte.l Die Produktion ist jedoch relativ kompliziert: Das Ausgangsmaterial muss vor Ort mittels Schnellpyrolyseanlagen energetisch verdichtet werden, ehe es sich wirtschaftlich in die eigentlichen Anlagen zur Herstellung des Treibstoffs Technologie (KIT)

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Gdnzlich anders verhdlt es sich mit der Gewinnung von Baumaterial aus Stroh. Es braucht lediglich einen Acker mit trockenem Stroh, einen Traktor, eine Hochdruckba]lenpresse und einen Wagen, und schon kann das Ballenpressen beginnen. Heraus kommen, je nachdem, welche Presse eingesetzt wird, Kieinstrohballen

oder Grossballen. Erstere weisen lVlasse von etwa 35x45x70 cm auf und lassen sich dementsprechend leicht haindisch als Ddmmmaterial verbauen. Nachteilig hierbei wirkt sich allerdings das Hofesterben aus: Besass friiher praktisch jeder Nebenerwerbsbauer, der Korn anbaute und Vieh hielt, eine solche Strohpresse, sind die n4aschinen heute rar geworden. Die Hofe werden grosser, die helfenden Hdnde weniger. Der Trend gehtklar zu den Grossballenpressen, die quaderformige Ballen herstellen. Sehr oft sind auch Rundballenpressen anzutreffen, doch diese Form bietet sich frir das Bauen naturlich kaum an. Ob gross oder klein, als Baumate-

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rial eignen sich grundsdtzlich beide quaderformigen Ballen. Fur diese Baustrohballen fi.nden bevorzugt l!-

Getreidesorten mit <festeren> Halmeigenschaften Verwendung, etwa Winterweizen, Dinl<el oder Roggen.

Nicht genormt und trotzdem sinnvoll Ist die Herstellung der Ballen noch recht einfach - das Wichtigste ist die ausreichende Pressung und Trockenheit des l\{aterials -, gestaltet sich die Weiterverarbeitung zu den gewiinschten Bauteilen wie Wdnden, Dach frir Nutztiere, Ztgabe in Biogasanlagen, Abdeckmaterial im Kleingarten - und bislang noch eher selten in der thermischen an kennt es als Einstreu

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Verwertung: Stroh flndet zwar Verwendung, besitzt aber nach wie vor oft das Image des Nebenprodukts der Getreideproduktion. Je nach Region wird Stroh in der Landwirtschaft auch gar nicht genutzt - es verbleibt auf dem Acker und wird nach dem Getreidedrusch wieder in den Boden eingepflrigt. Dieser Kreislauf fordert die Humusbildung, allerdings ist es doch schade um das lVlaterial. Auch der Tausch Stroh gegen lVlist respektive Gr.iIIe zur Dringung ist unter Bauern durchaus ribliche Praxis.

oder auch Bodenplatten schon anspruchsvolier. Denn

frir den Strohbau existieren bisher keine Normen, auf die sich die Ausfrihrenden berufen konnen. Es gibt zwar Richtlinien - etwa die Strohbaurichtlinie des Fachverbands Strohballenbau Deutschland

e. V.

-, diese hat aber

derzeit nicht den Rang einer anerkannten Regel der Technik. Fiir bestimmte Bauteilaufbauten bestehen allgemeine bauaufsichtliche Zulassungen, die jedoch nur

in Deutschland giiltig sind. Zertifi zierte Baustrohballen mit ETA-Zulassung (European Technical Assessment) gibt es in Deutschland und 0sterreich. Und in der Schweiz wird Stroh als Eco-1-Ddmmmaterial anerkannt, was fr.ir eine IVlinergie-Eco-Zertiflzierung relevant ist.

Wo es an Normen fehlt, mrissen gesunder 1\{enZukrinftig konnte sich die Sichtweise auf schenverstand, bauliches und bauphysikalisches Ver Stroh dndern und das lVlaterial eine grossere Wert- stdndnis und nicht nietzt Erfahrung in die Bresche schdtzung erfahren. Als Ausgangsprodukt fiir syn- springen. Die Zauberworter im Strohbau unterscheiden thetische Treibstoffe etwa bietet es sich an. Seit riber sich dabei nicht von denen bei anderen organischen zehn Jahren forscht man am Karlsruher Institut ftir Ddmmmaterialien: Luftdichtheit des Gebriudes und

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Die 202O fertiggestellte Neuiiberbauung des Bombasei-Areats in NSnikon ZH isf die erste Strohhaussiedlung der Schweiz, entworfen vom Atelier Schmidt. Verwendet wurden Kleinstrohballen in einer Holzstdnderbauweise.

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lnnenraum im Bombasei-Areal. Der Strohbau ltisst sich nur auf grund der Wandstiirke und des behaglichen Wohnklimas erahnen.

in der Schweiz und im benachbarten Ausland umdiffusionsoffene B auweise. D auerhaft - feuchtes Stroh ten gesetzt. Anhand einigerBeispiele aus seinen Referenzen beginnt zu faulen. Daher gilt es, Kondenswasseranfall oder anderweitig eindringende Feuchtigkeit in einer lassen sich im Strohbau gringige lVlethoden beleuchten.

Strohkonstruktion zu vermeiden. Auch anderen Problematiken - etwa Brandgefahren, Nagetieren und Der Klassiker: Strohballen im Holzstdnder Ungeziefer - begegnet man am besten mit einem geAuf dem Bombasei-Areal in Ndnikon ZH kam die eigneten Konstruktionsaufbau.

Werner Schmidt, Architekt aus Trun GR, gehort heute wohl am meisten umgesetzte Strohbauweise zum zu den Pionieren des Strohbaus. Das Atelier Schmidt, Einsatz: Ein Holzstdnderbau, der die Tragfunktion des heute von seiner Tochter und seinem Sohn gefrihrt, hat Gebdudes ribernimmt, wird mit Kleinstrohballen gefrillt, die verschiedenen iVloglichkeiten in zahlreichen Projek- die somit die Wandebenen bilden. Das Stroh ist in

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diesem Fall also nicht lasttragend (Abb. S. 221. Die Wdnde werden hier riber 35 cm tief, da die Strohballen

Die Alternative: Bestand hinter Stroh

natrirlich noch verkleidet werden. Dies geschieht oftmals mit Verputz - vor ailem im Innenbereich eignen sich Lehmputze aufgrund ihrer feuchteregulierenden Eigenschaften hervorragend (vgl. TEC21 3-4l2015 und TEC2I 9-lO/2ol7l. Wegen ihrer wetterfesteren Eigenschaften kommen aussen oft Kalkputze zum Einsatz.

Das Stroh kann dabei gleichzeitig als Putztrdger dienen.

Die aufgetragenen Putze haben noch weitere Vorteile: Sie machen die Strohwand feuerbestiindig - im Nor-

Das Potenzial an energetisch aufzuwertenden Gebiiuden ist gigantisch. Nahezu alle gemauerten Hduser aus den

malfall kann eine 30-minutige Brandbesteindigkeit problemlos erreicht werden; Strohballen gelten aufgrund ihrer dichten Pressung schon ohne Beschichtung als normal entflammbarer Baustoff. Aber auch Ausfiihrungen bis zu 90-minutiger Brandbesttindigkeit

(F90-B) sind moglich. Auch gegen Nagetiere und Schzid-

Iinge helfen die Verputze zusdtzlich. Zudem kann die erforderliche Luftdichtheit der Wiinde uber die Putze leichter umgesetzt werden.

Bei diffusionsoffener Bauweise der Wdnde sind aber auch anstelle oder als Ergdnzung von Verputzen

Beplankungen der Strohballen riblich. Hinterh.iftete Fassaden bieten sich hierfur geradezu an.

Die Vorteile der Holzstdnderbauweise - sehr hoher Vorfertigungsgrad im Werk und eine schnelle lvlontage auf der Baustelle - kommen dem Strohbau entgegen. Der Einbau der Ballen kann unter geregel

ten klimatischen Bedingungen in der Abbundhalle erfolgen, und ein regensicheres Dach ldsst sich ebenfalls schon vorbereiten. Als Resultat erhdlt man eine Konstruktion, die einen sehr geringen Energieaufwand im Herstellungsprozess aufweist. Im Gegensatz zu anderen eingesetzten Ddmmstoffen ist das Stroh unbehandelt, braucht keine Verpackung und enthdlt keine Klebstoffe, Aufschdumer oder dhnlichen chemischen Zutaten - vom Nylonstrick des Ballens einmal abgesehen. Und auch der Energieverbrauch beim Gebdudebetrieb wird sich in Grenzen halten: Die Wrirmeleitfrihigkeit von Stroh betrdgt etwa 0.045 WmK und liegt damit im Bereich von Steinwolle und anderen gdngigen Ddmmstoffen.

1970er-Jahren und frriher weisen Deflzite im Energieverbrauch auf. Die verwendeten Steine waren da-

mals noch nicht auf Energieeinsparung optimiert, Ddmmungen, wenn riberhaupt eingebaut, oft in zu geringer Stiirke ausgefiihrt und die hierbei verwendeten lVlaterialien nicht gerade der Gesundheit zutrriglich.

Wiirmebnicken nahm man damals noch gelassen die erste Olkrise kam erst 1973.

Gern packt man diese Gebtiude heute in Wiir-

meddmmverbundsysteme ein

-

mineralische Diimm-

stoffe oder Polystyrole kommen oft zum Einsalz. Zwar sind die Diimmstoffe gesundheitlich nicht mehr so pro blematisch wie einst, ihr energetischer Herstellungs-

aufwand ist gleichwohl hoch und eine spdtere Ent sorgung teuer. Kleinstrohballen konnen hier eine echte Alternative darstellen. <lVlontiert> respektive vor eine Steinwand aufgestellt und befestigt, wie bei der Casa Steila lVlar in Susch GR (Abb. unten), erfullt solch eine Konstruktion die Vorgaben an den Wdrmedurchgangskoeffizienten (U-Wert) der SIA 380/1 spielend: 0.25 Wm'zK frir eine Wand bei einem Umbau-fiir einen Neubau liegt der Wert bei 0.17 Wm2K - werden durch die Strohdrimmung weit unterschritten. Je nach Steinstdrke und Aufbau der Konstruktion wird auch der lVlinergie-A-Wert von 0.1 Wm2K erreicht. Das Passivhaus ist mit Stroh keine Utopie. Die Wand erhdlt durch die starke Ddmmung zwar eine beachtliche Tiefe - z. B. 35 cm Ziegel und 35 cm Strohballen, dazu noch Putzschichten oder dergleichen , allerdings punktet eine solche Konstruktion vor allem mit zwei Dingen: Die Steinwand liegt durch die Aussenddmmung komplett im Warmen und bringt eine immense thermische Speichermasse ins Gebdude. Das Gebdude reagiert deshalb trd:ge auf schnelle Temperaturschwankungen und gleicht diese aus; ein <Treibhausgefiihl> bleibt somit aus. Zudem gewdhrleistet die vorhandene verputzte Steinmauer die erforderliche Luftdichtheit des Ge bdudes: Eine verputzte Steinwand gilt als ausreichend

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Bei der 2014 erfolgten Instandsetzung der Casa Steila I\4ar in Susch liess das Atelier Schmidt Kleinstrohballen als Aussendtimmung vor die Fassade setzen. Die durch die Strohballen tiefen Fensterlaibungen harmonieren gut mit dem Engadiner Baustil.

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Lasffragende Grossslrohballenbauweise beim Neubau des Ausilellungs- und Biirogebiiudes des Garlenbauunternehmens Gartist in Bubikon ZH.2016 entwarf das Atelier Schmidt die Dachkonstruktion als Kraggewdlbe aus Strohballen (oben). Die so gewollten, organischen Putzkanten Iassen die Strohbauweise erahnen (darunter).

luftdicht. Und wenn die ndchste Generation das Haus so nicht mehr haben will, lassen sich die Strohballen ausbauen und l<onnen thermisch verwertet, kompostiert oder auf einem Acker eingepfltigt werden. Zuriick zum Ursprung - ohne grossen Recyclingaufwand.

gibt

es nur im lVldrchen. Beim lasttragenden Strohbau kommen oft Grossballen zum Einsatz. Ihre Abmessungen sind etwa 12Ox70x250 cm. Aufgrund der hohen Pressdichte und ihres Gewichts von etwa 300 kg ist ein

Einbau von Hand nicht mehr moglich. Allerdings ist auch eine lasttragende Bauweise mit Kleinballen mogLasttragende Strohballen: lich. Den beiden lVlethoden gemeinsam ist, dass die Dachlasten riber eine geeignete Konstruktion - etwa Wenn dem Wolf die Puste ausgeht einen Ringanker oder eine Platte - auf die Strohballen Dass ein Wolf ein Haus umpustet, etwa das Ausstel- ribertragen werden. Aufgrund der zu erwartenden lungsgebdude eines Gartenbauunternehmens aus last- Setzungen wartet man mit einem Verputz der Wiinde tragenden Strohballen in Bubikon ZH (Abb. oben), einige Wochen. Das unterschiedliche Setzungsverhalten

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der steifen Fenster- und Turlaibungen zum nachgiebigeren Stroh muss man hierbei im Auge behalten. Die Ddmmung und auch der Schallschutz sind aufgrund der Schwere und Dicke der Grossballen herausragend.

Aber auch hier gilt es, die Luftdichtheit sicherzustellen.

Aufgrund der hoheren Anforderungen beim Bau der Konstruktionen und nicht zuletzt der benotigten Fldchen fiir die Wiinde wird diese Bauweise frir eine breit gestreute Anwendung kaum infrage kommen.

Nicht lasttragende Grossballen Nicht lasttragende Grossballen einzusetzen ist selbstverstiindlich machbar. Sie konnen wie Kleinballen als Ddmmung vor eine Wand gestellt werden. Energetisch liefert dies aufgrund ihrer Stiirke einen immensen Vorteil. Allein - die Ballen konnten natr.irlich noch mehr; in Versuchen hielten sie Lasten bis zu 15 t/m2 Druck stand.

Das hatten Werner Schmidt und die HTW Chur bereits vor Jahren erprobt. Hohe Belastungen gehen bei Strohballen allerdings mit grossen Stauchungen einher - der E-Modul eines Grossballens liegtnurbei etwa 0.4N/mm2,

Holz hingegen bei etwa 10000 N/mm2, Stampflehm bei ca. 600 N/mm2. Auch eine Holzstdnderbauweise mit Grossballen ist moglich, wird aber selten umgesetzt.

Interessant kann das am ehesten fiir Strohproduzenten selbst sein - sprich Landwirte, die Stroh selbst anbauen und den benotigten Fuhrpark samt Grossballenpresse besitzen. Dann kann es - wie beim Hofladen in Eselsburg (D), vom Atelier Schmidt entworfen - zu einer ungewcihnlichen Konstrul<tion frihren (Abb. rechts).

- in Deutschland drirfen Strohballen nicht lasttragend eingesetzt werden konnte man das Stroh hier nicht statisch verbauen.

Aus gesetzlichen Grtnden

Strohdumm ist anders Stroh ist frir das Bauwesen geeignet - in seiner Reinform als gepresster Ballen, auch ohne Weiterbehandlung zu Strohprodukten. Durch die direkte Verwendung des schnell nachwachsenden Rohstoffs bleibt der energetische Erzeugungsaufwand dusserst tief * 0.85 IVIJ/kg nicht erneuerbarer Primdrenergieinhalt (pEI) entfrillt auf Stroh ab <Werk>, in diesem Fall ab Acker. Steinwolle schldgt hier mit 23 IWJ/kg, expandiertes polystyrol (EPS) gar mit 105 lVIJ/kg zu Buche.2 Im strohgeddmmten Haus zu sitzen ist alles andere als strohdumm und hdtte auch Rumpelstilzchen gefallen. HAtte es sich aus seinem Gold mal lieber ein Strohhaus gebaut. r Peter Seitz, Redaktor Bauingenieurwesen

Nicht lasf f ragende respekf ive f eillasttragende Grossslrohballen bilden beim 20I6 erfolgten Neubau des Hofladens der Biotal Hofgemeinde in Eselsburg (D) die Aussenwdnde.

Die Tragfunktion ubernimmt die Holzkonstruktion.

Die Strohballen fertigte die Hofgemeinschaft selbst an.

@ Kennwerle Stroh

Kennwerfe Mineralwolle

Wdrmeleitfdhigkeit )" WmK 0.052 (Rechenwert; eher tiefer bis 0.045)

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Dichte in kg/m3 ca. 100 120 {Kleinballen) bis 220 (Grossballen)

200 400 (gepresst)

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Anmerkungen 1 www.bioliq.d

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2 Fachagentur Nachwachsende Rohstoffe e.V. (FNR): 1\{arktiibersicht - Dammstoffe aus nachwachsenden Rohstoffen. Gtlzow-Priizen 20 17. www.fnr.de

Dichte in kg/m3 60-140 (lose) Wasserdampfdiffusions

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Brandverhalten DIN 4102 82 (normal entflammbar)

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Alternatlve: I-lanf Am MonViso Institut im Piemont experimentiert eine Gruppe um Professor Tobias Luthe mit systemischer Innovation wie der Umsetzung einer bioregionalen Kreislaufwirtschaft. Dazu gehdrt auch die Wiederbelebung von Hanf - in zeitgentissischen Ltisungen kommt das nur noch selten verwendete Naturmaterial zu neuem Einsatz.

Text: Danielle Fischer

ie Vorteile von Hanf, einer der riltesten Kulturpflanzen, nicken gerade wieder ins Bewusstsein verschiedener Branchen. Gemeint ist jedoch nicht die Gattung Cannabis, sondern Industriehanf, der kaum Tetrahydrocannabinol (THC)

Luftreinigung und Feuchtigkeitsregulation rihnliche Eigenschaften wie Lehm, sorgt also fiir ein gesundes Wohnklima. Durch das schnelle Wachstum und die jtihrliche Ernte bindet die Hanfpflanze sehr viel mehr CO, pro Fltiche als zum Beispiel Holz. Die Vorteile sind umso ausgepreigter, je ldnger die Schriben dauerhaft in enthdlt, als Rauschmittel also nicht taugt. In den Bergen Baumaterial gespeichert werden. wachsen diese Pflanzen in einem Vierteljahr etwa drei Warum also wird nicht vermehrt mit Hanf gelVleter hoch; in der Ebene gibt es sechs lVleter hohe Ex- baut? Tatsdchiich gibt es Hauser aus den nur minimal emplare - je nach Feldgrosse eine enorme Biomasse. lastabtragenden Hanfkalksteinen, die ein- oder - er<Hanf ist mit seinen markigen, bekannten Bldttern und gdnzt mit tragenden Holz- oder Betonsl<eletten - auch den mdnnlichen und weiblichen Exemplaren mit deut- mehrstockig sind. Solche Bauten errichtet die Firma licher Bliite optisch interessant. Wenn man mit einer Hanfstein aus Stidtirol. Inhaber Werner Schonthaler ist Drohne aus der Luft fllmt, sehen die Grrintone aus wie auch an Projekten am }llonViso Institut beteiligt. lVlit eine spezielle lVloosart im Wald>, beschreibt es Tobias Partnern wie der ETH Zririch forscht man auf verschie Luthe, der die Projekte im IVIonViso Institut in der pie- denen Ebenen an tragfdhigeren Kompositmaterialien. montesischen Gemeinde Ostana leitet.

Untersucht werden Baumaterialien aus Hanfkomposit Hanf wirkt sich positiv auf das Okosystem aus. mit Scheben, die einen sehr guten, bereits industriell Seine starken Wurzeln lockern den Boden und ziehen standardisierten Ddmmwert haben. Zum einen geht Schwermetalle in die Pflanze, er benotigt keine Herbi man der Frage nach, wie sich die Hanfkalksteine lastabzide oder Pestizide, ist ohne viel Wasser genugsam und tragend machen lassen. Hier soll das Geopolymer Kaobietet Jungtieren wie Rehkitzen Schutz. Je nach Sorte lin helfen - also Porzellanerde, die in China, Indien, werden mehr Fasern oder Nr.isse produziert - Letztere Brasilien, aber auch in Polen, Osterreich, England und eignen sich fur Lebensmittel wie lVlehl oder 01. Manche Deutschland abgebaut wird. Es ersetzt den Kaik und bleiben bis in den Oktober stehen - ideal fur Bienen, macht die Steine strukturell berechenbar, damit man die die Pollen zu Hanfhonig verarbeiten. Campanile ist mit ihnen mehrstockig mauern und Beton und Ziegel eine Hanfsorte mit starken Stdngeln, Fasern und hol- ersetzen kann. Eine andere Technologieinnovation bezernem Anteil, den Schdben, die sich frir biobasiertes trifft den 3-D-Druck mit demselben lVlaterial, um WdnPlastik oder Hanfkompositmaterialien am Bau eignen. de vorzufertigen. Die Innosuisse finanziert die Innovationen - Forschung mit Praxisnutzen, die auch fiir die

Ein gutes Produkt verbessern

Schweizer Okonomie einen lVlehrwert generieren soll.

Am Ende des Lebenszyklus konnen die Steine Hanf am Bau ist genereil ein vielversprechendes Thema. geschrottet werden. Das lVlaterial eignet sich dann fr.ir Die Hanfschdben lassen sich mit Naturkalk im Kaltluft- Schuttddmmungen und als neues Komposit oder ldsst verfahren zu Ziegeln pressen. Die Verbindung macht sich als Dringergranulat auf einem FeId verteilen. Hier das I\[aterial steinhart und bestdndig gegenuber dusse- stellt sich allerdings die Frage, ob der Boden je nach ren Einfliissen. Gute thermische Eigenschaften machen lVlenge zu basisch wird; auch die ortliche Dringeverordeine zusdtzliche Ddmmung riberflussig: Ein l\flinergie- nung gilt es zu berricksichtigen. Die WiederverwerStandard wird bereits mit monolithischen Steinen um tungsstrategien sollen auch mit Kaolin funktionieren. die 30-40 cm Stdrke erreicht. Hanfkalk hat bezriglich All diese Zusammenhdnge werden am IVIonViso Institut

28

Vom Feld ans Haus

aEc2t to/2021

t

Eine Wand an einem Annex am <Doppiol wurde unter Anleitung des Experten Werner Schonthaler von der Firma Hanfstein mif Hanfkalksteinen gemauert.

1

bei der Entwicklung des regenerativen l\{aterials systemisch miteinbezogen. Dabei betrachtet man nicht nur Okonomie und Okobitanz, sondern auch die Herkunft aller IVlaterialkomponenten. Wie ldsst sich die Pflanze iiber das Bauen hinaus verwenden, was geschieht mit der Landschaft - wie also verdndern Hanffelder die Alpenregionen? Die Pflanze eignet sich vor allem ftr Berggebiete in der Schweiz und in angrenzenden Ldndern. Der Fokus auf die Berge hat einen guten Grund: Hanf gedeiht in den Bergzonen 3 und 4, also bis auf etwa 1900 m ii.IVI. Dort gibt es generell zu viel Viehhaltung.

Die Tiere werden fiir einen Uberschuss an lVlilch und Fleisch genutzt und geben riber ihr Verdauungssystem zu viel lVlethangas ab. Hier konnte sich Hanf zur alternativen Einnahmequelle frir Bergbauern entwickeln.

Luthe begleitet die Bachelorarbeit von lVlalou Geerlings, die die okonomische Wertschopfung in einer Bundner Bergregion pro Arbeitsstunde und die Reduktion des Eintrags an Ndhrstoffen wie Nitrat in die Boden, verglichen mit der Viehwirtschaft, berechnet. Hanfanbau bringt rundum Vorteile, die Nachfrage steigt und damit auch der lVlarktpreis - eine Chance fur Regionen mit weniger guten Briden oder steilen Hanglagen. Doch dazu gilt es lokale Kompetenzen zu ergninden: das Wissen um die Pflanze und ihre Bewirtschaftung.

Case Studies

in Hanf

Das <Doppio> mit zwei Wohnungen im l\{onViso entstand anstelle eines verfallenen, traditionell mit Natursteinen gemauerten Landwirtschaftsbaus. Die alten Steine wur-

den mit neuen Holzmodulen zu einem Plusenergiehaus kombiniert, das tiber eine PV-Anlage 2OOo/o der selbst benotigten Energie produziert. Hanf kam dabei vielfeiltig zum Einsatz: Eine Annexwand ist mit Hanfkalksteinen gemauert, und eine Wandnische vor dem Entree

ist aus Stampfhanf. Beide sind in Zusammenarbeit mit dem Erfinder Werner Schonthaler und der lokalen Firma Calce Piasco entstanden. Hanfschdben wurden auch fr.ir die Schall- und Wdrmeddmmung in einem Spalt von

l5 cm zwischen den beiden Haushdlften verwendet.

Im Obergeschoss sind die Wrinde mit Hanfschriben verkleidet und verputzt, die Holzboden sind mit Hanffa sern geddmmt. Hanfvliesstreifen fungieren als schallentkoppelnde Schicht zwischen den Deckenbalken und den Hartholzboden in beiden Etagen. Schliesslich sind auch die Spalten zwischen den Holzfensterrahmen und den Holzwdnden mit Hanffasern ausgestopft.

An einem anderen Gebiiude, der Taverne, so1len

wieder schlichte Systeme wie die Hanfziegel von Werner Schonthaler verbaut werden. Auch dieses Gruppen-

haus entsteht mit allen moglichen Hanfbaustoffen.

Damit verbunden ist ein weiteres ETH-Projekt, an dem Schonthaler und ein Stucl<ateur aus dem Unterengadin,

der alte Hduser renoviert, mitwirken. Ihr Ziel ist es, einen Hanfddmmputz fiir Aussen- und einen fur Innenwdnde mit Kalk sowie unverkohlten und verkohlten Hinter einer Holzverkleidung: Hanf kann auch ftir Naturbeton verwendef werden. I\4an mischte die Hanfschdben mit magnesithaltigem Sumpfkalk aus der Region, Das Gemisch

wurde in eine Schalung gekippt und durch Stampfen verfestigt.

Hanfschdben zu entwicl<eln. Letztere haben gr6ssere Oberfldchen und konnen so mehr Feuchtigkeit regulieren und Feinpartikel filtern als herkdmmliche Putze.

Vom Feld ans

TEC2L t0/2021

Haus

29

I ,1

_l

lr

'l l

ii _t

:

.

Die lnnendemmung einer Bar im Slenna Center in Flims GR mauerte die Stdliroler Firma Hanfstein 2019: Aufgrund des natiirlichen Bindemittels sind die Hanfsteinejedoch nicht tragfdhig. 30 Tage nach Produktion erreichen sie 0.3 I\{Pa. Allerdings hdrtet der Kalk iiber Jahrzehnte weiter aus urrd erreicht langsam die maximale Tragfrihigkeit, Deshalb muss beim Bau hoherer Bauten mit

Hanfkalksteinen die Statik wie bei anderen Baumaterialien durch Holz- oder Stahltriiger bzw. Betonskelette gelost werden.

: :

T T

,*,

Die Schiben werden in einer Dampfmaschine gertisfef, die sie vom Pektin befreit, dann zerkleinert und dem Kalk beigegeben.

Bindemittel isf magnesithaltiger Sumpfkalk, die mineralisierten Hanfschdben sind brandbestiindig.

30

Vom Feld ans Haus

TEC2L t0/2021

Natrirlich gab es auch Umwege - Hanf ist nicht immer die richtige Wahl. So hdtten frir das Baufundament Hanfschdben anstelle von Stahlarmierungen zum Einsatz kommen sollen. Beim dafrir verwendeten Romankalk entsteht mit hydraulischem Kalkstein, Sand und Wasser ein COr-armer, schnell hdrtender Beton. Doch

Hanf kalkstein Die Firma Hanfstein produziert pro Tag rund 400 m'z 38 cm dicke Steine. Kombiniert mit einer Skelettbauweise sind mehrere Stockwerke moglich. In Spanien hat die I'irma eine Baustelle mit drei }u{ehrfamilienhdusern, in Ziirich entsteht im Friihjahr 202I ein X{ehrfamilienhaus.

Geliefert wird in die EU und nach China.

o

Hanfkalksfein

rmeleitf

0.07

ii hi

gkeit

fiihrten. Die Losung fand man darin, auf Hanf zu verzichten und die Dicke des Fundaments zu erhohen.

Auf die Frage nach weiteren Nachteilen des Hanfs erwahnt Luthe die mangelnde Erfahrung mit dem Hanfanbau auf 1500 m Hohe. Zuerst musste das

Druckfestigkeit

Kennwerfe

0.32 IVIPa s erdampfdiffusions widerstand u

Wqs

I ha Hanf speichert ca. 20 t CO, jtihrlich Wd

die Hanffasern bildeten Knduel, die zu Lufteinschhissen

trocken 4.3, nass 3.8 7"

W(mk)

Rohdichte

richtige Saatgut mit Keimversuchen ausgetestet werden.

Im feuchten Sommerklima entsteht eine lokale, schnell wachsende Biomasse - der Hanf braucht aiso wtihrend des Keimens einen Wachstumsvorsprung. Der Zeitraum derAussaat und das Wetter spielen eine Rolle. Vor allem die ersten zwei Wochen sind anspruchsvoll, so Luthe.

Es gab in der Region oft Starkhagel bis im Juni, und die klimatischen Extremereignisse nehmen zu. Wird zu friih gesiit, zerstort der Hagel die Keimlinge, ist man zu spiit dran, bekommen die Pflanzen nicht mehr geniigend Tageslicht, um den Wachstumskreislauf abzuschliessen.

Hanf ist eine einjiihrige Pflanze und muss jedes Jahr neu gesdt werden. Die Wurzeln bleiben im Boden und werden zu Humus. Damit Hanf gedeiht, muss der Boden aber entsprechend vorbereitet werden: Aufgrund der vielen Jahrzehnte Viehwirtschaft sind die Grasnarben tiber dem kaum 15 cm dicken A-Horizont des Humus so hart und dick, dass sie von Hand schwer zu bearbeiten sind. Deshalb offnete im ersten Jahr ein Traktor die

Spez. WiirmekapazitAt 1870 J/(kgK)

Brandverhalten DIN EN 13501-1

300 kg/m3

Kalksandstein Die Kennwerte sind u. a. abhiingig von der Steinroh dichteklasse (RDK) und der Steindruckfestigkeitsklasse (SFK). Ftir einen tiblichen Kalksandstein der RDK 1.4 und SFK 12:

o

Kennwerte Kalksandsfein

Wdrmeieitftihigkeit 0.7 W/(mk)

Rohdichte I210-1400 kg/m3

Wa

s

serdampfdiffu sions

trocken 25, nass )"

-

widerstand u 10

Spez, W2irmekapazitdt 1000 J/(kgK)

Brandverhalten DIN EN 13501 I Klasse A1

Druckfestigkeit 15 N/mm2 (15 MPa)

,r.*.s**

I

Die Proben mifverschiedenen Anteilen an Hanfschdben und Nalurkalk entstanden, um die Oualitdt des Romankalks fiir das Fundament des <Doppio> auszutesten. Da die Schiiben, die die Stahlarmierung hetten ersetzen sollten, Knduel bildeten, riss der Beton. Das Fundament, auf dem die l{uster stehen, wurde daraufhin verbreitert, auf eine Armierung wurde gdnzlich verzichtet.

Vom Feld ans

"IEC27 tO/2021

Haus

31

Grasschicht. Doch bereits im Folgejahr, als man den Boden weniger aufwendig bearbeitete, gediehen die Pflanzen spdrlicher. Deshalb soll heuer eine Frdse die Erde oberfldchlich bearbeiten, und je nach Wetter ist eine lVlulchabdeckung vorgesehen, diejedoch nicht zu dick sein darf, weil die Samen darunter sonst faulen.

Schweizer Pldne in den Aipen 2019 wurden in der Schweiz insgesamt 288 ha Nutzhanf gepflanzt. In Graubinden bauen die <Hanfpioniere> seit vielen Jahren Hanf an. Im Kanton riberlegt man, wo sich mit grossen Feldern eine sinnvolle regionale Wertschopfung stiften, zirkuliire Okonomie und gleichzeitig Klimaschutz betreiben und bodenschridigende lWilchwirtschaft reduzieren ldsst. Der voluminose Hanfreisig soll wegen des Volumens an Ort und Stelle so verarbeitet werden, dass nur die Fasern und die Schiiben transportiert werden - ohne Blatter und Gesamtstdngel, die zu lVledizinalprodukten oder Lebensmitteln verarbeitet werden. Das schafft Arbeitspldtze im ldndlichen Raum und treibt die Entwicklung eines nachhaltigen Okonomiemodells mit lokalen Kreisldufen und Dienstleistungen voran. Naturlich braucht es auch bei den Behorden und der Bevolkerung vor Ort Offenheit und den Willen zur Verdnderung - im Piemont wie in der Schweiz mrisste man Gewohnheiten aufgeben und sich auf ein neues Landschaftsbild einstellen. .

D

. _:*--

;

antelle Fischer, Redaktorin Architektur

o Am 2. Juni 2021 fi.ndet bei SIAinForm in der Reihe <Bauressource Schweiz Wege in die Kreisiaufwirtschaft> ein Webinar zum Thema statt. Weitere Informationen auf

Auch ein Hanfprodukt: lm Monviso lnstifuf konnen Kurse belegt werden, bei denen die Teilnehmer Skier mit Hanfkomposit erstellen; Fasern und lokales Leichtholz

www.sia.ch/deldienstleistungen/sia-inform/detaiU

werden dabei mit Naturprotein-Leim geklebt.

Mehr dazu: www,monviso-insf ilule.org

event

ltozslncl't I

Leinen als Vlies

o

Die grossten Produktionen in Europa beflnden sich in Nordfrankreich. es besteht allerdings eine grosse Konkurrenz aus Asien. Alles an Leinen kann verwen

det werden: die Korner fLir 01, die Einstreu fiir Tiere, die Langfasern fiir Textilien und die Kurzfasern - also der

Reststoff aus den Langfasern - fiir

Ddmmungen. Das Rosten erfolgt durch Regen und Sonne, indem die Pflanzen nach dem Schneiden auf dem Feld liegen bleiben. Nach etwa neun Wochen fdrben sie sich schwarz, und die Faserbiindel haben sich vom Gewebe gelost. Dann werden die Sttingel gebrochen, der Holz-

kern geknickt und zerkleinert und

so

I

ein Grossteil der Holzteilchen entfernt.

Anschliessend wird alles in einer Schleuder geschwungen, bis nur noch die langen Leinenfasern fiir Textilien

iibrig sind. Die kurzen Fasern konnen

Kennwerte Leinenvlies

t

ha Leinen bindet.iAhrlich ca.3.7 t CO, Wtirmeleitf tihiekeit )"

zu formbestiindigen, schimmel- und

0.04W(mk)

insektenresistenten Demmplatten ver arbeitet werden. Aus ihnen wird auch Vlies gefertigt, das durch Stdrke- oder Polyesterfasern verfestigt wird. Verschiedene Salze dienen als Brandschutzmittel. Je nach Verarbeitung sind die Platten nachher nicht mehr kom postierbar. . (df)

Rohdichte SO-aO kC/m

Schallabsorbtionsgrad 0.07 Spez. Wdrmekapazitdt 1550 2300 J/(kgK) Brandverhalten nicht feuerfest (82), (Brandschutz klasse) EI 45 bei 12 cm

HEMPLIMECONSTRUCTION ,

A guideto building withhemplime€omposites

HEMPLIMECONSTRUCTION A guideto buildingwith hemplimecomposites RachelBevanandTomWoolley

With contributions by Ian Pritchett. RalphCarpenter,Peter Walker and Mike Duckett

brepress

CONTENTS

Published by IHS BRE Press ('\

IHS BRE Presspublications are available from www.ihsbrepress.com

C rH -/11l

~~S BRE Press

/.,,,) /\,

l

-e,a.1.1bibliothe.4-

Willoughby Road Bracknell RG12 8FB Tel: 01344 328038 Fax: 01344 328005 Email: brepress@ihs.com Printed on paper sourced from responsibly managed forests.

CONTENTS vii ix

Oxfordshire © Lime Technology Ltd Middle right: Clay Fields, Elmswell, Bury St Edmunds, Suffolk

LISTOFILLUSTRATIONS FOREWORD ABOUT THENATIONAL NON-FOOD CROPS CENTRE {NNFCC) ACKNOWLEDGEMENTS

© Riches Hawley Mikhail Architects Ltd Bottom right: Hemp crop being harvested © Lime Technology Ltd

1

INTRODUCTION

1

1.1 1.2 1.3

What are zero-carbon buildings?

Searching for alternatives UK government policy History of hemp building An outline of hemp lime construction

2 4 4

Methodology of the study Performance of hemp lime Supply of hemp materials for construction Glossary of terms

5 5 6 7

2

WHATIS HEMP CONSTRUCTION?

9

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

Non-food crops Hempcrete or hemp lime?

Construction of walls Timber frame

9

Cover images: Main and top right: Lime Technology head office, Abingdon,

Index compiled by Margaret Binns: www.binnsindexing.co.uk Requests to copy any part of this publication should be made to the publisher: IHS BRE Press Carston, Watford WD25 9XX Tel: 01923 664761 Email: brepress@ihs.com The author, publisher, Defra and NNFCC accept no responsibility, nor liability, in any manner whatsoever for any error or omission, nor any loss, damage, injury, or adverse outcome of any kind incurred as a result of the use of the information contained in this book or reliance upon it. Readers are advised to seek specific professional advice relating to their particular construction project and circumstances before embarking on any building work.

Reasonable care has been taken to ensure the accuracy of the information in the book at the time of printing. Drawings and

1.4 1.5 1.6 1.7 1.8 1.9

Blockmaking Finishes and spraying Renovating existing buildings Sourcing materials and DIY Acceptance and accreditation of hemp

X

xi

10 11 12 12 14 15 15 17

technical details are indicative and typical only and final detailing for any project remains the responsibility of the designer.

3

CASE EXAMPLES OFHEMPLIMEBUILDINGS 19

3.1

Adnams brewery warehouse and distribution centre Reconstruction of old timber frame foundry

EP 85 © Rachel Bevan and Tom Woolley 2008 First published 2008 ISBN 978-1-84806-033-3 Please note that some of the work practices shown in the photographs in this book may not comply with current Health and Safety Regulations.

3.2 3.3 3.4 3.5 3.6 3.7

Barn conversion Self-build renovation of bungalow Two-storey extension Social housing Lime Technology Ltd head office Brakspear summerhouse Tradical exhibition stand at Ecobuild

3.8 3.9 3.10 Clay Fields social housing 3.11 House extension for traditional cottage 3.12 WISE Building, CAT

20 21

22 22 22

22 23 24 24 25 26 26

4

GROWING HEMPFORBUILDING

27

5

BUILDING CONSTRUCTION TECHNIQUES

31

5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10

Timber frame construction for walls Wet or dry construction?

Offsite construction Wall details

39 40 40 40 41 42 43 43 44 44

Methods of placing hemp and lime Block construction Roof construction Footings and ground floor slabs Surface finishes Membranes Fixings Renovation and use in historic buildings Plastering with hemp and lime Timber frame and hemp model

45 47 47

6

MIXES ANDMATERIALS

49

6.1

Specifying the hemp Specifying the lime-based binder Further notes on Iime

49

5.11 5.12 5.13 5.14

6.2 6.3

44

50 51

7

DURABILITY, MOISTURE, VENTILATION, INDOOR AIRQUALITY AND THERMAL PERFORMANCE

53

7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8

Ventilation Thermal performance

55 57

Continuity of insulation Thermal mass and comfort Overall thermal performance of hemp lime Cavity walls, roofs and floors Air tightness In summary

58 58 59 60

8

SCIENTIFIC ISSUES RELATED TOHEMPLIME 63

60 61

CONTENTS

Published by IHS BRE Press ('\

IHS BRE Presspublications are available from www.ihsbrepress.com

C rH -/11l

~~S BRE Press

/.,,,) /\,

l

-e,a.1.1bibliothe.4-

Willoughby Road Bracknell RG12 8FB Tel: 01344 328038 Fax: 01344 328005 Email: brepress@ihs.com Printed on paper sourced from responsibly managed forests.

CONTENTS vii ix

Oxfordshire © Lime Technology Ltd Middle right: Clay Fields, Elmswell, Bury St Edmunds, Suffolk

LISTOFILLUSTRATIONS FOREWORD ABOUT THENATIONAL NON-FOOD CROPS CENTRE {NNFCC) ACKNOWLEDGEMENTS

© Riches Hawley Mikhail Architects Ltd Bottom right: Hemp crop being harvested © Lime Technology Ltd

1

INTRODUCTION

1

1.1 1.2 1.3

What are zero-carbon buildings?

Searching for alternatives UK government policy History of hemp building An outline of hemp lime construction

2 4 4

Methodology of the study Performance of hemp lime Supply of hemp materials for construction Glossary of terms

5 5 6 7

2

WHATIS HEMP CONSTRUCTION?

9

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

Non-food crops Hempcrete or hemp lime?

Construction of walls Timber frame

9

Cover images: Main and top right: Lime Technology head office, Abingdon,

Index compiled by Margaret Binns: www.binnsindexing.co.uk Requests to copy any part of this publication should be made to the publisher: IHS BRE Press Carston, Watford WD25 9XX Tel: 01923 664761 Email: brepress@ihs.com The author, publisher, Defra and NNFCC accept no responsibility, nor liability, in any manner whatsoever for any error or omission, nor any loss, damage, injury, or adverse outcome of any kind incurred as a result of the use of the information contained in this book or reliance upon it. Readers are advised to seek specific professional advice relating to their particular construction project and circumstances before embarking on any building work.

Reasonable care has been taken to ensure the accuracy of the information in the book at the time of printing. Drawings and

1.4 1.5 1.6 1.7 1.8 1.9

Blockmaking Finishes and spraying Renovating existing buildings Sourcing materials and DIY Acceptance and accreditation of hemp

X

xi

10 11 12 12 14 15 15 17

technical details are indicative and typical only and final detailing for any project remains the responsibility of the designer.

3

CASE EXAMPLES OFHEMPLIMEBUILDINGS 19

3.1

Adnams brewery warehouse and distribution centre Reconstruction of old timber frame foundry

EP 85 © Rachel Bevan and Tom Woolley 2008 First published 2008 ISBN 978-1-84806-033-3 Please note that some of the work practices shown in the photographs in this book may not comply with current Health and Safety Regulations.

3.2 3.3 3.4 3.5 3.6 3.7

Barn conversion Self-build renovation of bungalow Two-storey extension Social housing Lime Technology Ltd head office Brakspear summerhouse Tradical exhibition stand at Ecobuild

3.8 3.9 3.10 Clay Fields social housing 3.11 House extension for traditional cottage 3.12 WISE Building, CAT

20 21

22 22 22

22 23 24 24 25 26 26

4

GROWING HEMPFORBUILDING

27

5

BUILDING CONSTRUCTION TECHNIQUES

31

5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10

Timber frame construction for walls Wet or dry construction?

Offsite construction Wall details

39 40 40 40 41 42 43 43 44 44

Methods of placing hemp and lime Block construction Roof construction Footings and ground floor slabs Surface finishes Membranes Fixings Renovation and use in historic buildings Plastering with hemp and lime Timber frame and hemp model

45 47 47

6

MIXES ANDMATERIALS

49

6.1

Specifying the hemp Specifying the lime-based binder Further notes on Iime

49

5.11 5.12 5.13 5.14

6.2 6.3

44

50 51

7

DURABILITY, MOISTURE, VENTILATION, INDOOR AIRQUALITY AND THERMAL PERFORMANCE

53

7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8

Ventilation Thermal performance

55 57

Continuity of insulation Thermal mass and comfort Overall thermal performance of hemp lime Cavity walls, roofs and floors Air tightness In summary

58 58 59 60

8

SCIENTIFIC ISSUES RELATED TOHEMPLIME 63

60 61

LISTOFILLUSTRATIONS

HEMP LIME CONSTRUCTION

9

STRUCTURES, FIREANDACOUSTICS - MEETING BUILDING STANDARDS ANDREGULATIONS71

9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8

Structures Structural overview Future research Resistance to bending Resistance to shear Time-dependent deformation Structural performance Superstructure design

9.9 9.10 9.11 9.12 9.13 9.14

Roofs Internal walls Foundations Site preparation and moisture resistance Fire regulations Acoustic performance

71 71 71 71

72 72 72 73 73 73 73 74 75 75

11

NATURAL PRODUCTS FORUSEIN CONJUNCTION WITHHEMP LIME 85

11.1 11.2 11.3 11.4

Spraying hemp onto permanent shuttering Using other natural insulations Other crop-based materials Related products in more detail

85 85 86 86

12

THEADVANTAGES OFHEMP ANDLIME

91

12.1 Government energy targets for housing and building 12.2 Modern methods of construction 12.3 Costs 12.4 Future development and information sources 12.5 Summary of the main advantages of hemp construction

13 10

LIFECYCLE ANDCARBON SEQUESTRATION77

10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8

Initial considerations Potential tools What is life cycle assessment?

What is embodied carbon?

Issues for further consideration Assessing hemp-based building products BRE environmental profiles method BRE environmental profiles

77 78 78 78 78

10.9 The ecopoints score 10.10 Embodied energy and embodied carbon

80 80 80 82

10.11 Environmental product declarations 10.12 Cement and concrete 10.13 Extracts from the life cycle assessment carried out in France 10.14 Summary

78 79 79

82 84

REFERENCES ANDNOTES

91 93 94 94

Aston Clinton, Buckinghamshire © Crawford/Radclyffe

XII

Fig 3. 10: Brakspear summerhouse, Worcester

24

4

Fig 3. 11: Brakspear summerhouse, Worcester (under construction)

24

95

Fig 1. 1: Seven-storey office building in Clermont Ferrand which uses hemp lime blocks © Lhoist UK Ltd

Fig 3.12: Tradical exhibition stand, Ecobuild 2007

24

Fig 1.2: Interior of the Adnams brewery warehouse, Abingdon, Oxfordshire© Lime Technology Ltd

7

Fig 3.13: Clay Fields, Elmswell (under construction).

Shuttering in place waiting for hemp lime to be sprayed © Riches Hawley Mikhail Architects Ltd

25

97

Shuttering for hemp lime wall, Aston Clinton, Buckinghamshire© Crawford/Radclyffe

8

Fig 3.14: House extension, Oxford© Sally Harper

26

APPENDIX 1: RESISTANCE TOCOMPRESSION AND 101 STRESS-STRAIN PROPERTIES 2: THERMAL MEASUREMENTS ON APPENDIX LIMEANDHEMP MIXTURES (SUMMARY)

105

USEFUL CONTACTS

107

INDEX

LISTOFILLUSTRATIONS

109

Fig 2.1: Hemp shiv with lime being mixed © Lime Technology Ltd

10

Fig 3.15: Timber frame construction - WISE building, Centre for Alternative Technology

26

Fig 2.2: Timber frame and hemp lime infill being tamped by school children. Hemp lime is 'child's play'© Ashley Pettit Architects

11

Fig 3. 16: Hemp lime being sprayed - WISE building, Centre for Alternative Technology

26 27

Fig 2.3: Hemp lime blocks© Lime Technology Ltd

13

Fig 4. 1: Hemp crop being harvested in Essex © Lime Technology Ltd

Fig 2.4: Hemp lime block wall in French office building© Lhoist UK Ltd

13

Fig 4.2: Kenaf crop in Malaysia

30

Fig 2.5: Hemp lime being sprayed at the Lime Technology Ltd head office building © Lime Technology Ltd

14

Fig 2.6: Hemp lime infill being used to renovate an historic timber frame house© Marianne Suhr

15

Figs5. 1 to 5.5 © Ralph Carpenter, Modece Architects

Fig 2. 7: Lime mortar silo

16

Delivery of hemp bales to Hemcore

18

Fig 3. 1: Adnams brewery warehouse general view

20

Fig 3.2: Adnams brewery warehouse interior

20

Fig 3.3: Green light project, detail of interior

21

Fig 3.4: Greenlight project general view

21

Fig 3.5: Croxley Green barn conversion © Lime Technology Ltd

22

Fig 3.6: Pield Heath Avenue, London © Richard Monkhouse

22

Fig 3. 7: Ralph Carpenter's house, Suffolk

22

Fig 3.8: Haverhill social housing hemp house and adjoining brick house

22

Fig 3.9: Lime Technology office at Milton Park, Abingdon

23

Fig 5.1: Cast hemp wall with timber rainscreen

37

Fig 5.2: Warm roof eaves with hemp lime cast around sloping rafters

32

Fig 5.3: Solid wall with hemp lime wall cast onto inner face

32

Fig 5.4: Brick plinth to timber frame wall (with hemp-based slab)

33

Fig 5.5: Hemp lime slab with joists and boarded floor

33

Figures5.6 to 5. 10 © Lime Technology Ltd Fig 5.6: Plan of corner and window jamb with permanent internal shuttering board and timber frame, for spray application of hemp lime

34

Fig 5. 7: Plan of corner and window jamb with hemp lime cast between temporary shuttering boards, timber frame in centre, with rendered outer face

35

Fig 5.8: Section with timber frame on an internal face and hemp lime sprayed or cast

36

Fig 5.9: Head of wall with sloping ceiling (Warm Roof) with timber frame on inner face with permanent shuttering

37

LISTOFILLUSTRATIONS

HEMP LIME CONSTRUCTION

9

STRUCTURES, FIREANDACOUSTICS - MEETING BUILDING STANDARDS ANDREGULATIONS71

9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8

Structures Structural overview Future research Resistance to bending Resistance to shear Time-dependent deformation Structural performance Superstructure design

9.9 9.10 9.11 9.12 9.13 9.14

Roofs Internal walls Foundations Site preparation and moisture resistance Fire regulations Acoustic performance

71 71 71 71

72 72 72 73 73 73 73 74 75 75

11

NATURAL PRODUCTS FORUSEIN CONJUNCTION WITHHEMP LIME 85

11.1 11.2 11.3 11.4

Spraying hemp onto permanent shuttering Using other natural insulations Other crop-based materials Related products in more detail

85 85 86 86

12

THEADVANTAGES OFHEMP ANDLIME

91

12.1 Government energy targets for housing and building 12.2 Modern methods of construction 12.3 Costs 12.4 Future development and information sources 12.5 Summary of the main advantages of hemp construction

13 10

LIFECYCLE ANDCARBON SEQUESTRATION77

10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8

Initial considerations Potential tools What is life cycle assessment?

What is embodied carbon?

Issues for further consideration Assessing hemp-based building products BRE environmental profiles method BRE environmental profiles

77 78 78 78 78

10.9 The ecopoints score 10.10 Embodied energy and embodied carbon

80 80 80 82

10.11 Environmental product declarations 10.12 Cement and concrete 10.13 Extracts from the life cycle assessment carried out in France 10.14 Summary

78 79 79

82 84

REFERENCES ANDNOTES

91 93 94 94

Aston Clinton, Buckinghamshire © Crawford/Radclyffe

XII

Fig 3. 10: Brakspear summerhouse, Worcester

24

4

Fig 3. 11: Brakspear summerhouse, Worcester (under construction)

24

95

Fig 1. 1: Seven-storey office building in Clermont Ferrand which uses hemp lime blocks © Lhoist UK Ltd

Fig 3.12: Tradical exhibition stand, Ecobuild 2007

24

Fig 1.2: Interior of the Adnams brewery warehouse, Abingdon, Oxfordshire© Lime Technology Ltd

7

Fig 3.13: Clay Fields, Elmswell (under construction).

Shuttering in place waiting for hemp lime to be sprayed © Riches Hawley Mikhail Architects Ltd

25

97

Shuttering for hemp lime wall, Aston Clinton, Buckinghamshire© Crawford/Radclyffe

8

Fig 3.14: House extension, Oxford© Sally Harper

26

APPENDIX 1: RESISTANCE TOCOMPRESSION AND 101 STRESS-STRAIN PROPERTIES 2: THERMAL MEASUREMENTS ON APPENDIX LIMEANDHEMP MIXTURES (SUMMARY)

105

USEFUL CONTACTS

107

INDEX

LISTOFILLUSTRATIONS

109

Fig 2.1: Hemp shiv with lime being mixed © Lime Technology Ltd

10

Fig 3.15: Timber frame construction - WISE building, Centre for Alternative Technology

26

Fig 2.2: Timber frame and hemp lime infill being tamped by school children. Hemp lime is 'child's play'© Ashley Pettit Architects

11

Fig 3. 16: Hemp lime being sprayed - WISE building, Centre for Alternative Technology

26 27

Fig 2.3: Hemp lime blocks© Lime Technology Ltd

13

Fig 4. 1: Hemp crop being harvested in Essex © Lime Technology Ltd

Fig 2.4: Hemp lime block wall in French office building© Lhoist UK Ltd

13

Fig 4.2: Kenaf crop in Malaysia

30

Fig 2.5: Hemp lime being sprayed at the Lime Technology Ltd head office building © Lime Technology Ltd

14

Fig 2.6: Hemp lime infill being used to renovate an historic timber frame house© Marianne Suhr

15

Figs5. 1 to 5.5 © Ralph Carpenter, Modece Architects

Fig 2. 7: Lime mortar silo

16

Delivery of hemp bales to Hemcore

18

Fig 3. 1: Adnams brewery warehouse general view

20

Fig 3.2: Adnams brewery warehouse interior

20

Fig 3.3: Green light project, detail of interior

21

Fig 3.4: Greenlight project general view

21

Fig 3.5: Croxley Green barn conversion © Lime Technology Ltd

22

Fig 3.6: Pield Heath Avenue, London © Richard Monkhouse

22

Fig 3. 7: Ralph Carpenter's house, Suffolk

22

Fig 3.8: Haverhill social housing hemp house and adjoining brick house

22

Fig 3.9: Lime Technology office at Milton Park, Abingdon

23

Fig 5.1: Cast hemp wall with timber rainscreen

37

Fig 5.2: Warm roof eaves with hemp lime cast around sloping rafters

32

Fig 5.3: Solid wall with hemp lime wall cast onto inner face

32

Fig 5.4: Brick plinth to timber frame wall (with hemp-based slab)

33

Fig 5.5: Hemp lime slab with joists and boarded floor

33

Figures5.6 to 5. 10 © Lime Technology Ltd Fig 5.6: Plan of corner and window jamb with permanent internal shuttering board and timber frame, for spray application of hemp lime

34

Fig 5. 7: Plan of corner and window jamb with hemp lime cast between temporary shuttering boards, timber frame in centre, with rendered outer face

35

Fig 5.8: Section with timber frame on an internal face and hemp lime sprayed or cast

36

Fig 5.9: Head of wall with sloping ceiling (Warm Roof) with timber frame on inner face with permanent shuttering

37

1111

FOREWORD

HEMP LIME CONSTRUCTION

Fig 5. 10: Section through wall with timber frame outer face and rainscreen

38

Fig 8.6: Thermal diffusivity of various materials

66 67

Fig 5.11: Modcell hemp lime panel, Ecobuild exhibition 2007

40

Fig 8. 7: Dampening of diurnal temperature variation at different depths in Tradical Hemcrete Fig 8.8: Thermal effusivity of various materials

67

Fig 5.12: Spraying in progress © Henry Thompson, The Old Builders Company

42

Fig 8.9: Monitoring of the Lime Technology Ltd head office during April 2007

68

Fig 5.13: Diaphragm wall of chalk, lime and hemp blocks at Adnams brewery under construction

42

Limecrete being placed in wall footings at the WISE building© Centre for Alternative Technology

70

Fig 5.14: Hemp lime insulation cast between rafters © Lime Technology Ltd

43

Fig 9.1: Aerial view of WISE building© Alternative Technology

74

Fig 5.15: Hemp lime floor being cast © Henry Thompson, The Old Builders Company

44

84

Fig 5. 16: Hemp and lime infill in an historic building© Marianne Suhr

45

Fig 1O.1: French Regional Government Office multistorey building (with detail inset) using hemp block infill walls© Lhoist UK Ltd Fig 11. 1: Straw bale house in Putley, Herefordshire

86

Fig 5.17: Bungalow in Hillingdon, London, with external hemp lime render© Richard_Monkhouse

46

Fig 11.2: York Eco-Depot constructed with Modcell

87

Fig 5.18: Stone building in Chalons-en-Champagne renovated with hemp lime plaster

46

Fig 11.3: Heraklith boards used for permanent shuttering with hemp lime

89

Fig 5.19: Internal hemp lime plaster in Eardisland, Herefordshire

47

Fig 11.4: Hemp loft board© Natural Fibre Technology

89

Fig 5.20: Model of timber frame and hemp© Lime Technology Ltd

47

Fig 11.5: Breathe hemp insulation in B&Q

89

48

3D view of the WISE building at the Centre for Alternative Technology constructed with hemp lime and rammed earth walls© Pat Borer Architect

90

Strata wall, Aston Clinton, Buckinghamshire © Crawford/Radclyffe

Fig 6.1: Hemcore horse bedding bale

49

96

Fig 6.2: Tradical hemp bale© Lime Technology Ltd

50

Clay Fields, Elmswell (under construction) © Riches Hawley Mikhail Architects Ltd

Fig 6.3: Tradical mixing plant at Milton Park

51

Fig 7.1: Timber clad hemp lime wall at the Greenlight project with Ralph Carpenter

53

Fig 7.2: Mould growth due to inadequate ventilation and insulation in a precast concrete building

55

Fig 7.3: Effects of humidity

56

Plastering a hemp wall © Crawford/Radclyffe

62

Centre for

strawbale panels

Figures8.1 to 8. 9 © Arnaud Evrard

Fig 8.1: Different moisture states of Hemcrete

64

Fig 8.2: Graph of water content vs. relative humidity

64

Fig 8.3: Thermal capacity of various materials

65

Fig 8.4: Temperature profile through Hemcrete

65

Fig 8.5: Heat flow through various materials

66

FigA 1.1: Comparison of hemp lime cube and cylinder test response in compression © Peter Walker

101

FigA 1.2: Hemp lime cylinder test in compression © Peter Walker

102

FigA 1.3: Stress-strain responses of hemp lime cylinders under compression loading © Peter Walker

102

FigA 1.4: Results from hemp lime cylinder tests, undertaken at the University of Bath in 2005 (Kioy, 2005) © Peter Walker

104

Hemp lime wall in a workshop in Ralph Carpenter's

106

house, unplastered

All illustrations not credited © Tom Woolley.

FOREWORD For far too long, 'eco' building has focussed on energy efficiency in use, with super insulated structures, renewable energy and rainwater collection. This is all very well, but such structures have continued to be built from materials with highembodied energy or toxic production processes such as concrete, steel and plastic. This book sets out a form of building that offers a real alternative to standard cavity wall construction, providing a carbon neutral option that is easy to use, diverse in its application and cost competitive.

I was introduced to hemp lime construction when searching for an alternative to wattle and daub in the repair of my own timber-framed house. Hemp lime was breathable, and therefore compatible with the ancient timber frame, and could be sculpted to shape. It was also far more

thermally efficient than the daub, and did not shrink to create gaps around the edge of the panel. I was so impressed by the material, I went on to use hemp lime for a contemporary extension on the same building. In both instances, the material has proved a roaring success.

Whether you require practical information for building in hemp lime, scientific data for further research or simply want to understand the material better, this book is packed full of all the information you could need. I only wish it had been available before I embarked on my own hemp lime building projects.

Marianne Suhr · MRICS,SPABLethabyScholar

1111

FOREWORD

HEMP LIME CONSTRUCTION

Fig 5. 10: Section through wall with timber frame outer face and rainscreen

38

Fig 8.6: Thermal diffusivity of various materials

66 67

Fig 5.11: Modcell hemp lime panel, Ecobuild exhibition 2007

40

Fig 8. 7: Dampening of diurnal temperature variation at different depths in Tradical Hemcrete Fig 8.8: Thermal effusivity of various materials

67

Fig 5.12: Spraying in progress © Henry Thompson, The Old Builders Company

42

Fig 8.9: Monitoring of the Lime Technology Ltd head office during April 2007

68

Fig 5.13: Diaphragm wall of chalk, lime and hemp blocks at Adnams brewery under construction

42

Limecrete being placed in wall footings at the WISE building© Centre for Alternative Technology

70

Fig 5.14: Hemp lime insulation cast between rafters © Lime Technology Ltd

43

Fig 9.1: Aerial view of WISE building© Alternative Technology

74

Fig 5.15: Hemp lime floor being cast © Henry Thompson, The Old Builders Company

44

84

Fig 5. 16: Hemp and lime infill in an historic building© Marianne Suhr

45

Fig 1O.1: French Regional Government Office multistorey building (with detail inset) using hemp block infill walls© Lhoist UK Ltd Fig 11. 1: Straw bale house in Putley, Herefordshire

86

Fig 5.17: Bungalow in Hillingdon, London, with external hemp lime render© Richard_Monkhouse

46

Fig 11.2: York Eco-Depot constructed with Modcell

87

Fig 5.18: Stone building in Chalons-en-Champagne renovated with hemp lime plaster

46

Fig 11.3: Heraklith boards used for permanent shuttering with hemp lime

89

Fig 5.19: Internal hemp lime plaster in Eardisland, Herefordshire

47

Fig 11.4: Hemp loft board© Natural Fibre Technology

89

Fig 5.20: Model of timber frame and hemp© Lime Technology Ltd

47

Fig 11.5: Breathe hemp insulation in B&Q

89

48

3D view of the WISE building at the Centre for Alternative Technology constructed with hemp lime and rammed earth walls© Pat Borer Architect

90

Strata wall, Aston Clinton, Buckinghamshire © Crawford/Radclyffe

Fig 6.1: Hemcore horse bedding bale

49

96

Fig 6.2: Tradical hemp bale© Lime Technology Ltd

50

Clay Fields, Elmswell (under construction) © Riches Hawley Mikhail Architects Ltd

Fig 6.3: Tradical mixing plant at Milton Park

51

Fig 7.1: Timber clad hemp lime wall at the Greenlight project with Ralph Carpenter

53

Fig 7.2: Mould growth due to inadequate ventilation and insulation in a precast concrete building

55

Fig 7.3: Effects of humidity

56

Plastering a hemp wall © Crawford/Radclyffe

62

Centre for

strawbale panels

Figures8.1 to 8. 9 © Arnaud Evrard

Fig 8.1: Different moisture states of Hemcrete

64

Fig 8.2: Graph of water content vs. relative humidity

64

Fig 8.3: Thermal capacity of various materials

65

Fig 8.4: Temperature profile through Hemcrete

65

Fig 8.5: Heat flow through various materials

66

FigA 1.1: Comparison of hemp lime cube and cylinder test response in compression © Peter Walker

101

FigA 1.2: Hemp lime cylinder test in compression © Peter Walker

102

FigA 1.3: Stress-strain responses of hemp lime cylinders under compression loading © Peter Walker

102

FigA 1.4: Results from hemp lime cylinder tests, undertaken at the University of Bath in 2005 (Kioy, 2005) © Peter Walker

104

Hemp lime wall in a workshop in Ralph Carpenter's

106

house, unplastered

All illustrations not credited © Tom Woolley.

FOREWORD For far too long, 'eco' building has focussed on energy efficiency in use, with super insulated structures, renewable energy and rainwater collection. This is all very well, but such structures have continued to be built from materials with highembodied energy or toxic production processes such as concrete, steel and plastic. This book sets out a form of building that offers a real alternative to standard cavity wall construction, providing a carbon neutral option that is easy to use, diverse in its application and cost competitive.

I was introduced to hemp lime construction when searching for an alternative to wattle and daub in the repair of my own timber-framed house. Hemp lime was breathable, and therefore compatible with the ancient timber frame, and could be sculpted to shape. It was also far more

thermally efficient than the daub, and did not shrink to create gaps around the edge of the panel. I was so impressed by the material, I went on to use hemp lime for a contemporary extension on the same building. In both instances, the material has proved a roaring success.

Whether you require practical information for building in hemp lime, scientific data for further research or simply want to understand the material better, this book is packed full of all the information you could need. I only wish it had been available before I embarked on my own hemp lime building projects.

Marianne Suhr · MRICS,SPABLethabyScholar

HEMP LIME CONSTRUCTION ACKNOWl!EDGEMENTS -

ABOUTTHENATIONAL NON-FOOD CROPS CENTRE (NNFCC) The National Non-Food Crops Centre (NNFCC) is the UK's national centre for renewable materials and technologies. It uses its extensive market knowledge and technical expertise to build supply chains for plant-derived renewable materials so that good ideas become products that people buy. It establishes and explains the economic, environmental and social benefits of non-food crop materials. And it provides evidence and advice to support the development of policy.

The NNFCC is a not-for-profit company which receives grant funding from Defra but is independent of government and of industry. The Centre acts on the evidence and takes care not to promote non-food crop solutions that do not provide real benefits.

The NNFCC is very interested in crop-derived construction materials, which can contribute to sustainable construction issues including: embodied

carbon, energy consumption, waste, and providing greater occupier comfort, for example through buffering moisture content. The Centre is working with several companies developing renewable construction materials. It also publishes information including newsletters and factsheets as well as more detailed studies including a recent life cycle analysis of natural fibre insulation materials.

For more information about the NNFCC's work in the construction field, contact them by: Email: enquiries@nnfcc.co.uk Tel: 01904 435182 or visit their website www.nnfcc.co.uk

ACKNOWLEDGEMENTS Marshall Add idle, Innovation Relay Centre Iris Anderson, Defra Laurent Arnaud, ENTPE Francois Bardout, Lhoist Ltd Alan Boyd, AB33 Bernard Boyeux, Balthazar et Cotte Ralph Carpenter, architect, Modece Architects Professor A De Herde, Universite catholique de Louvain, Atchitecture et Climat Mike Duckett, managing director, Hemcore Ltd Dr Arnaud Evrard, Universite catholique de Louvain, Atchitecture et Climat Steve Coodhew, University of Plymouth Mike Haynes, Lhoist UK Ltd John Hobson, Hemcore Ltd Ian Law, NNFCC Brian Murphy, Creenspec Cary Newman, Plant Fibre Technology Brian Pilkington, University of Plymouth Ian Pritchett, managing director, Lime Technology Ltd Simone Pritchett, Lime Technology Ltd

NNFCC

Rhydwen Ranyl, Centre for Alternative Technology Michel Rizza, Balthazar et Cotte Ryman Stephen, Defra John Stewart, Queens University Belfast Henry Thompson, The Old Builders Company Jeremy Tomkinson, NNFCC Professor Peter Walker, director, BRE Centre in Innovative Construction Materials ' and Department of Architecture & Civil Engineering, University of Bath Gwyn Watkins, Lhoist UK Ltd David Williams, NNFCC John Williams, NNFCC Tim Yates, BRE and many more people, too numerous to mention

HEMP LIME CONSTRUCTION ACKNOWl!EDGEMENTS -

ABOUTTHENATIONAL NON-FOOD CROPS CENTRE (NNFCC) The National Non-Food Crops Centre (NNFCC) is the UK's national centre for renewable materials and technologies. It uses its extensive market knowledge and technical expertise to build supply chains for plant-derived renewable materials so that good ideas become products that people buy. It establishes and explains the economic, environmental and social benefits of non-food crop materials. And it provides evidence and advice to support the development of policy.

The NNFCC is a not-for-profit company which receives grant funding from Defra but is independent of government and of industry. The Centre acts on the evidence and takes care not to promote non-food crop solutions that do not provide real benefits.

The NNFCC is very interested in crop-derived construction materials, which can contribute to sustainable construction issues including: embodied

carbon, energy consumption, waste, and providing greater occupier comfort, for example through buffering moisture content. The Centre is working with several companies developing renewable construction materials. It also publishes information including newsletters and factsheets as well as more detailed studies including a recent life cycle analysis of natural fibre insulation materials.

For more information about the NNFCC's work in the construction field, contact them by: Email: enquiries@nnfcc.co.uk Tel: 01904 435182 or visit their website www.nnfcc.co.uk

ACKNOWLEDGEMENTS Marshall Add idle, Innovation Relay Centre Iris Anderson, Defra Laurent Arnaud, ENTPE Francois Bardout, Lhoist Ltd Alan Boyd, AB33 Bernard Boyeux, Balthazar et Cotte Ralph Carpenter, architect, Modece Architects Professor A De Herde, Universite catholique de Louvain, Atchitecture et Climat Mike Duckett, managing director, Hemcore Ltd Dr Arnaud Evrard, Universite catholique de Louvain, Atchitecture et Climat Steve Coodhew, University of Plymouth Mike Haynes, Lhoist UK Ltd John Hobson, Hemcore Ltd Ian Law, NNFCC Brian Murphy, Creenspec Cary Newman, Plant Fibre Technology Brian Pilkington, University of Plymouth Ian Pritchett, managing director, Lime Technology Ltd Simone Pritchett, Lime Technology Ltd

NNFCC

Rhydwen Ranyl, Centre for Alternative Technology Michel Rizza, Balthazar et Cotte Ryman Stephen, Defra John Stewart, Queens University Belfast Henry Thompson, The Old Builders Company Jeremy Tomkinson, NNFCC Professor Peter Walker, director, BRE Centre in Innovative Construction Materials ' and Department of Architecture & Civil Engineering, University of Bath Gwyn Watkins, Lhoist UK Ltd David Williams, NNFCC John Williams, NNFCC Tim Yates, BRE and many more people, too numerous to mention

llNTRODUCTION -

1 INTRODUCTION In 2006 we were commissioned by the National Non-Food Crops Centre (NNFCC) to investigate building construction using hemp lime composites and to write a guide to assist those who want to use and specify the materials. A year-long study funded by the Department for Environment, Food and Rural Affairs (Defra) has led to this guide.

In the UK, Europe and globally there is a general acceptance of the need to reduce carbon emissions and energy consumption. Over the past few years there has been growing interest in the concept of low- and zero-carbon buildings and methods of construction that can facilitate this.

Even those who deny that climate change is the result of human activities accept that fossil fuels are increasingly scarce and costly and that the impact of using non-renewable resources is unsustainable and likely to damage the environment. To safeguard both people and planet we have to develop alternative strategies for meeting our needs in building construction, transport, infrastructure, food and so on.

1.1

WHATAREZERO-CARBON BUILDINGS?

The general understanding of zero-carbon buildings is that they involve 'micro-generation', adding renewable energy equipment like solar panels and wind turbines to buildings. Certainly, UK government policy has focussed strongly on this and on reducing waste and water consumption. These ideas can be found in the Code for Sustainable Homes (Department for Communities and Local Government, 2008) and other sustainable building standards that are being applied by public sector bodies. Energy efficiency, in terms of increasing insulation, is a very important part of these policies but there has, until recently, been little concern about

the methods and materials that are used to achieve this, as long as energy consumption is reduced.

Recently, greater awareness has developed in which the nature of the materials and methods of building construction are seen as equally important.

It seems foolish to use fossil-fuel-based materials to manufacture insulation when we are trying to reduce our consumption of fossil fuels, yet the insulation industry is dominated by products that are petrochemical-based or require a lot of energy to produce. Many of these synthetic products also use highly toxic additives in the form of glues, binders and flame-retardants that can cause pollution.

Brominated flame-retardants are widespread in the natural environment owing to pollution and emissions from manufacturing and buildings. They have been found in worryingly high levels in the blood of volunteers tested by WWF (WWF-UK, 2003) and are causing concern among Inuit communities near the North Pole, who rely on fish that are now contaminated with toxic chemicals associated with synthetic building materials (The Guardian, 2007 [French LCA, 2005]). Demand for natural and non-toxic materials, as an alternative to synthetic products, is growing rapidly as public awareness of green issues has grown.

1.2

SEARCHING FORALTERNATIVES

Petrochemical-based synthetic materials do not biodegrade easily and create worrying problems for the future if they end up in landfill. Thus society has begun to look for natural materials that are renewable (ie materials that can be replaced without doing any damage to the environment), consuming minimal fossil fuel energy, and have minimal pollution and health risks. Crop materials like hemp and flax have become significant in the search for such alternatives.

llNTRODUCTION -

1 INTRODUCTION In 2006 we were commissioned by the National Non-Food Crops Centre (NNFCC) to investigate building construction using hemp lime composites and to write a guide to assist those who want to use and specify the materials. A year-long study funded by the Department for Environment, Food and Rural Affairs (Defra) has led to this guide.

In the UK, Europe and globally there is a general acceptance of the need to reduce carbon emissions and energy consumption. Over the past few years there has been growing interest in the concept of low- and zero-carbon buildings and methods of construction that can facilitate this.

Even those who deny that climate change is the result of human activities accept that fossil fuels are increasingly scarce and costly and that the impact of using non-renewable resources is unsustainable and likely to damage the environment. To safeguard both people and planet we have to develop alternative strategies for meeting our needs in building construction, transport, infrastructure, food and so on.

1.1

WHATAREZERO-CARBON BUILDINGS?

The general understanding of zero-carbon buildings is that they involve 'micro-generation', adding renewable energy equipment like solar panels and wind turbines to buildings. Certainly, UK government policy has focussed strongly on this and on reducing waste and water consumption. These ideas can be found in the Code for Sustainable Homes (Department for Communities and Local Government, 2008) and other sustainable building standards that are being applied by public sector bodies. Energy efficiency, in terms of increasing insulation, is a very important part of these policies but there has, until recently, been little concern about

the methods and materials that are used to achieve this, as long as energy consumption is reduced.

Recently, greater awareness has developed in which the nature of the materials and methods of building construction are seen as equally important.

It seems foolish to use fossil-fuel-based materials to manufacture insulation when we are trying to reduce our consumption of fossil fuels, yet the insulation industry is dominated by products that are petrochemical-based or require a lot of energy to produce. Many of these synthetic products also use highly toxic additives in the form of glues, binders and flame-retardants that can cause pollution.

Brominated flame-retardants are widespread in the natural environment owing to pollution and emissions from manufacturing and buildings. They have been found in worryingly high levels in the blood of volunteers tested by WWF (WWF-UK, 2003) and are causing concern among Inuit communities near the North Pole, who rely on fish that are now contaminated with toxic chemicals associated with synthetic building materials (The Guardian, 2007 [French LCA, 2005]). Demand for natural and non-toxic materials, as an alternative to synthetic products, is growing rapidly as public awareness of green issues has grown.

1.2

SEARCHING FORALTERNATIVES

Petrochemical-based synthetic materials do not biodegrade easily and create worrying problems for the future if they end up in landfill. Thus society has begun to look for natural materials that are renewable (ie materials that can be replaced without doing any damage to the environment), consuming minimal fossil fuel energy, and have minimal pollution and health risks. Crop materials like hemp and flax have become significant in the search for such alternatives.

HEMP LIME (ONSTRUCTION

! INTRODUCTION

The obvious renewable material is timber, but trees take many decades to grow and must be seen as a valuable resource that should be used with great care. Even with sustainable forest management and certification by the Forest Stewardship Council, it is not possible to replace synthetic materials entirely with those based on wood. There are many exciting new ecological products based on timber (building boards, wood fibre insulation products and so on).

Many of these products now use very little synthetic -glue and some are based on wood waste and low quality wood chippings. However, cellulose (which is what wood is) can be produced from crops that can be grown annually. Willow is being grown as a biomass crop for harvesting after only a few years and experiments have been carried out with a whole range of fibrous materials like miscanthus, flax and hemp. Burning these materials for energy is a controversial idea because of concerns about the amount of land required to grow them; instead, industry and agriculture have looked at cellulose and fibre-based products that have higher economic value and can replace synthetic products.

Natural insulation products have been made in recent times from a wide range of materials such as flax, wood fibre, wood waste, hemp and sheep'swool.

Despite their higher costs these materials are being used by many architects and builders as demand increases for ecological building. Indeed some suppliers of these materials have found it hard to keep up with demand.

Natural insulation quilts can cost four to five times more than glassfibre, but despite this their environmental benefits have created a new and expanding market Hemp lime construction provides a form of insulation that acts as a wall (as a weather shield) and also offers a radical new way of building for designers, developers and contractors. It is this alternative that is the main focus of this book.

Traditional, natural and low impact building methods have been in use for many years or have been developed recently. Cob (mixing mud and straw), rammed earth, adobe (unfired mud and straw bricks) and straw bale buildings are just a few examples. All of these techniques are explained in Natural building (Woolley T, 2006) and other recent publications (Earthmasonry, Morton T, 2008;

Rammed earth: Design and constructionguidelines, Walker P, Keable R, Martin will not be discussed here.

J, Maniatidis V, 2005)

so

Traditional and natural building techniques tend to be more attractive to self-builders, or where there is plenty of free or voluntary labour, as they are not always easily incorporated into mainstream construction. The exception to this is unfired earth bricks and blocks until the advent of hemp and lime. A number of mainstream companies are now producing these in commercial quantities, though few of these products can be used for external walling.

Hemp lime provides a form of construction

BOX1 EXTRACTS FROM THECODE FOR SUSTAINABLE HOMES Reduced carbon footprint of activities within the construction sector, and better use of resources: • Reduced daily water consumption in new buildings Zero net waste, at construction site level Effective use of government procurement

that can be built onsite quickly and efficiently or prefabricated offsite, allowing conventional mainstream builders to incorporate the materials into their normal practices with little adjustment.

power as an enabler to transform the market for innovative and sustainable solutions Development of voluntary agreements and initiatives by the construction industry and its clients with the aim of reducing the carbon footprint and use of resources within the built environment

Having a low impact, carbon-negative, sustainable form of construction that can be used in volume house building or even multi-storey office blocks, factories and warehouses is an exciting development that provides a genuine solution to demands for zero-carbon construction. As will be explained later, hemp lime can capture carbon dioxide and lock it up into buildings.

Greater uptake of training programmes, improving skills and increasing retention rates of skilled workers within a safer industry.

Proposed targets suggested are: •

1.3

UKGOVERNMENT POLICY

UK government policy has begun to recognise the importance of these issues by shifting the focus a little from energy efficiency and micro-generation to the nature of materials, resource consumption and health. In a consultation document on sustainable construction produced in August 2007 (BERR: www.berr.gov.uk), the focus of the proposed strategy is on the topics shown in Box 1.

The government has suggested commissioning a project to look at the scope for setting a target for the use of renewable materials in construction in the UK. If this goes ahead it should help to boost interest in hemp lime construction.

Another government initiative in England, the Code for SustainableHomes (Department for Communities and Local Government, 2008),

By 2012 a SO% reduction of construction, demolition and excavation waste to landfill compared to 2005 By 2015, zero net waste, at construction site level By 2020, zero waste to landfill 50% of products with type Ill Environmental Product Declarations by 2010 (proposed new target for industry) SO%of buildings and construction schemes over £1 m in value using stewardship and responsible sourcing principles by 2010 (proposed new target for industry).

BACKGROUND ANDRATIONALE FORACTION To assessfully the position of materials in a sustainability context requires consideration of a complex set of environmental, social and economic factors across their whole life cycle. Use of life cycle assessments(LCA) o(materials and products has advanced in recent years alongside improvements in lifecycle methodologies.

The aim is to understand which parts of the life cycle have the greatest impacts, and where and how interventions can be focussed to improve the environmental performance of products and services.

A programme of work within CEN (Comite Europeen de Normalisation) under Mandate 350 will provide a standardised voluntary methodology for the assessment of the integrated performance of buildings. The scope of the work is to develop a voluntary standardised methodology for the assessment of the sustainability aspects of new and existing construction works and for standards for the environmental product declaration of construction products. The resulting standards will provide the means for the quantification of the impacts of the construction industry and for understanding the resuIts of its decisions. .

Responsible sourcing is an area of growing importance to the construction sector. The supply chains delivering these products and the stewardship that they show to their 'service performance' (energy in use, thermal properties and ease of maintenance) and 'end of life' (how the material is recycled, recovered or disposed of) is a matter of utmost importance when considering sustainability objectives.

Much greater emphasis is placed on materials than before with: 50% of products with type Ill Environmental Product using stewardship and responsible sourcing principles by 2010.

The aim is to set up independently verified product stewardship certification schemes for the product sector. BRE is also starting a development process for a Responsible Sourcing of Materials scheme during 2007.

requires consideration of "the environmental impacts of construction materials for key construction elements and for responsible sourcing of materials".

The UK government has already had a programme of encouragement and support for renewable materials through the Biomass strategy

of the Department for Environment, Food and Rural Affairs) (Defra, 2007) and the establishment of the National Non-Food Crops Centre in York. This has given encouragement to industry to develop renewable crop-based materials. Pioneering work

on hemp for construction began in France in the late 1980s and the manufacture of natural building and insulation products in France, Germany, Switzerland and Poland is growing rapidly. Most natural building products sold in the UK are currently imported.

HEMP LIME (ONSTRUCTION

! INTRODUCTION

The obvious renewable material is timber, but trees take many decades to grow and must be seen as a valuable resource that should be used with great care. Even with sustainable forest management and certification by the Forest Stewardship Council, it is not possible to replace synthetic materials entirely with those based on wood. There are many exciting new ecological products based on timber (building boards, wood fibre insulation products and so on).

Many of these products now use very little synthetic -glue and some are based on wood waste and low quality wood chippings. However, cellulose (which is what wood is) can be produced from crops that can be grown annually. Willow is being grown as a biomass crop for harvesting after only a few years and experiments have been carried out with a whole range of fibrous materials like miscanthus, flax and hemp. Burning these materials for energy is a controversial idea because of concerns about the amount of land required to grow them; instead, industry and agriculture have looked at cellulose and fibre-based products that have higher economic value and can replace synthetic products.

Natural insulation products have been made in recent times from a wide range of materials such as flax, wood fibre, wood waste, hemp and sheep'swool.

Despite their higher costs these materials are being used by many architects and builders as demand increases for ecological building. Indeed some suppliers of these materials have found it hard to keep up with demand.

Natural insulation quilts can cost four to five times more than glassfibre, but despite this their environmental benefits have created a new and expanding market Hemp lime construction provides a form of insulation that acts as a wall (as a weather shield) and also offers a radical new way of building for designers, developers and contractors. It is this alternative that is the main focus of this book.

Traditional, natural and low impact building methods have been in use for many years or have been developed recently. Cob (mixing mud and straw), rammed earth, adobe (unfired mud and straw bricks) and straw bale buildings are just a few examples. All of these techniques are explained in Natural building (Woolley T, 2006) and other recent publications (Earthmasonry, Morton T, 2008;

Rammed earth: Design and constructionguidelines, Walker P, Keable R, Martin will not be discussed here.

J, Maniatidis V, 2005)

so

Traditional and natural building techniques tend to be more attractive to self-builders, or where there is plenty of free or voluntary labour, as they are not always easily incorporated into mainstream construction. The exception to this is unfired earth bricks and blocks until the advent of hemp and lime. A number of mainstream companies are now producing these in commercial quantities, though few of these products can be used for external walling.

Hemp lime provides a form of construction

BOX1 EXTRACTS FROM THECODE FOR SUSTAINABLE HOMES Reduced carbon footprint of activities within the construction sector, and better use of resources: • Reduced daily water consumption in new buildings Zero net waste, at construction site level Effective use of government procurement

that can be built onsite quickly and efficiently or prefabricated offsite, allowing conventional mainstream builders to incorporate the materials into their normal practices with little adjustment.

power as an enabler to transform the market for innovative and sustainable solutions Development of voluntary agreements and initiatives by the construction industry and its clients with the aim of reducing the carbon footprint and use of resources within the built environment

Having a low impact, carbon-negative, sustainable form of construction that can be used in volume house building or even multi-storey office blocks, factories and warehouses is an exciting development that provides a genuine solution to demands for zero-carbon construction. As will be explained later, hemp lime can capture carbon dioxide and lock it up into buildings.

Greater uptake of training programmes, improving skills and increasing retention rates of skilled workers within a safer industry.

Proposed targets suggested are: •

1.3

UKGOVERNMENT POLICY

UK government policy has begun to recognise the importance of these issues by shifting the focus a little from energy efficiency and micro-generation to the nature of materials, resource consumption and health. In a consultation document on sustainable construction produced in August 2007 (BERR: www.berr.gov.uk), the focus of the proposed strategy is on the topics shown in Box 1.

The government has suggested commissioning a project to look at the scope for setting a target for the use of renewable materials in construction in the UK. If this goes ahead it should help to boost interest in hemp lime construction.

Another government initiative in England, the Code for SustainableHomes (Department for Communities and Local Government, 2008),

By 2012 a SO% reduction of construction, demolition and excavation waste to landfill compared to 2005 By 2015, zero net waste, at construction site level By 2020, zero waste to landfill 50% of products with type Ill Environmental Product Declarations by 2010 (proposed new target for industry) SO%of buildings and construction schemes over £1 m in value using stewardship and responsible sourcing principles by 2010 (proposed new target for industry).

BACKGROUND ANDRATIONALE FORACTION To assessfully the position of materials in a sustainability context requires consideration of a complex set of environmental, social and economic factors across their whole life cycle. Use of life cycle assessments(LCA) o(materials and products has advanced in recent years alongside improvements in lifecycle methodologies.

The aim is to understand which parts of the life cycle have the greatest impacts, and where and how interventions can be focussed to improve the environmental performance of products and services.

A programme of work within CEN (Comite Europeen de Normalisation) under Mandate 350 will provide a standardised voluntary methodology for the assessment of the integrated performance of buildings. The scope of the work is to develop a voluntary standardised methodology for the assessment of the sustainability aspects of new and existing construction works and for standards for the environmental product declaration of construction products. The resulting standards will provide the means for the quantification of the impacts of the construction industry and for understanding the resuIts of its decisions. .

Responsible sourcing is an area of growing importance to the construction sector. The supply chains delivering these products and the stewardship that they show to their 'service performance' (energy in use, thermal properties and ease of maintenance) and 'end of life' (how the material is recycled, recovered or disposed of) is a matter of utmost importance when considering sustainability objectives.

Much greater emphasis is placed on materials than before with: 50% of products with type Ill Environmental Product using stewardship and responsible sourcing principles by 2010.

The aim is to set up independently verified product stewardship certification schemes for the product sector. BRE is also starting a development process for a Responsible Sourcing of Materials scheme during 2007.

requires consideration of "the environmental impacts of construction materials for key construction elements and for responsible sourcing of materials".

The UK government has already had a programme of encouragement and support for renewable materials through the Biomass strategy

of the Department for Environment, Food and Rural Affairs) (Defra, 2007) and the establishment of the National Non-Food Crops Centre in York. This has given encouragement to industry to develop renewable crop-based materials. Pioneering work

on hemp for construction began in France in the late 1980s and the manufacture of natural building and insulation products in France, Germany, Switzerland and Poland is growing rapidly. Most natural building products sold in the UK are currently imported.

HEMP LIME CONSTRUCTION

1.4

HISTORY OFHEMPBUILDING

Hemp composites for building construction have been used in France throughout the 1990s.

Restoration of historic half-timbered buildings required a substitute for wattle and daub and it was found that hemp - mixed with a lime-based binder provided a natural solution. It was also dimensionally stable and long-lasting. A number of architects and builders then began to experiment with its use for new construction. Timber frame buildings were -.constructed with a hemp lime mixture cast around the timber frame to create a kind of natural concrete.

A number of individual private houses and several social housing schemes were constructed using this form of building with apparently satisfactory results. Further experiments indicated that the hemp lime mixture could be used for floor screeds and in roofs. Over the past few years hemp lime products have been used to construct a number of non-housing projects including a seven-storey office building (Regional Government Office of Housing and Environment, Clermont Ferrand) for the French government and several other projects including significant rehabilitations of older buildings.

Fig 1.1:

1 INTRODUCTION

l.S AN OUTLINE OFHEMPLIME CONSTRUCTION The most typical form of hemp lime construction uses conventional timber frames with panels constructed of timber studs, and the hemp lime cast around the frame to create a solid wall. There is often no need to use timber sheathing boards, breather membranes, internal finishes like plasterboard and external cladding which can make normal timber frame construction rather complicated. The hemp lime provides a solid wall, acoustic and thermal insulation, and even an internal finish. Weather protection of the hemp lime is needed to shed precipitation and this can be provided by different finishes, including lime render, lapped timber boards, shingles, rainscreen tiles or lime-mortared brickwork. This uncomplicated method can reduce labour costs, speed up construction and simplify the building process.

The UK construction industry tends to exhibit a deeply conservative suspicion of unfamiliar building methods yet shows a surprising willingness to take on some new untried technological methods if they look cheaper and quicker. In order for hemp lime to be adopted it has to prove to a sceptical audience

Seven-storeyoffice building in Clermont Ferrandwhich useshemp lime blocks

of architects, builders and clients that it can meet Building Regulations and current new sustainability standards, and can also be technically approved, insurance approved, and affordable.

1.6 METHODOLOGY OFTHESTUDY The study for the NNFCC consisted of gathering as much information as possible about hemp construction and visiting many of the UK hemp construction projects. We attended a wide range of meetings organised by businesses in the sector including several research-based seminars with participants from France and Belgium. We interviewed architects, builders, timber frame manufacturers and material manufacturers. We assembled a team of experts to look at issues such as structural engineering, detail design, life cycle assessment (LCA), and specification and thermal performance.

During the course of the study a trade association, the Hemp Lime Construction Products Association (www.hemplime.org.uk), was established and a UK-based supply chain for production and distribution of materials was also set up. We were able to observe this process and also meet with new industrial participants from the mainstream construction industry. Large stands promoting hemp construction were built at the Ecobuild exhibition at Earls Court in London in February 2006 and February 2007 and several hemp lime training sessions have been held around the UK. This made it possible to meet with potential designers and specifiers of the material and to listen to their questions and concerns. The market is currently dominated by a small group of companies who have developed strong commercial ties but there are a few other suppliers of materials and competition is likely to grow as the material becomes more widely adopted.

While this has essentially been a desk-based study, we were able to carry out some thermal testing in order to check data and claims that might have been difficult to substantiate. We have also been able to observe and monitor a few hemp building projects under construction and have built a small model of a section of a building. We have

been given privileged access to results of building tests carried out by others both onsite and at the University of Bath, University of Plymouth and the National Physical Laboratory.

1.7

PERFORMANCE OFHEMPLIME

An interesting finding of the study is that current conventional methods for the testing and rating of insulating materials and building methods do not favour natural materials. Thus performance predicted by such methods may be exceeded in practice.

This raises a number of fundamental questions about existing methods of building science that are used to assessmaterials and building methods.

Current methods of testing and evaluating building materials, particularly in terms of thermal performance, must be questioned as they have been largely designed for lightweight synthetic materials with an assumption of steady-state conditions. Evidence suggeststhat hemp lime walls perform significantly better than would be predicted from conventional U-value figures. This created difficulties when BREevaluated the thermal performance of two hemp houses in Haverhill in Suffolk in 2001-2. These houses were compared with two identical houses of brick and block that used 100 mm of blown fibre Rockwool cavity fill insulation (BRE, 2002).

BRE found that the two hemp houses were functioning with lower heating bills at a temperature of 1 or 2 degrees higher than the control houses. This confirmed the suspicion that the conventional method of evaluating theoretical thermal efficiency, which predicted a poorer performance for the hemp houses, was wrong in practice. This is due to testing methods being designed for lightweight materials that are normally tested in a 'hot box'. This method does not take account of the ability of materials to store heat and absorb moisture, both of which affect thermal performance in practice. In order to demonstrate that hemp construction can provide better thermal performance than conventional materials it will be necessary to carry out a further series of tests of buildings once constructed and over a period of time and compare them with

HEMP LIME CONSTRUCTION

1.4

HISTORY OFHEMPBUILDING

Hemp composites for building construction have been used in France throughout the 1990s.

Restoration of historic half-timbered buildings required a substitute for wattle and daub and it was found that hemp - mixed with a lime-based binder provided a natural solution. It was also dimensionally stable and long-lasting. A number of architects and builders then began to experiment with its use for new construction. Timber frame buildings were -.constructed with a hemp lime mixture cast around the timber frame to create a kind of natural concrete.

A number of individual private houses and several social housing schemes were constructed using this form of building with apparently satisfactory results. Further experiments indicated that the hemp lime mixture could be used for floor screeds and in roofs. Over the past few years hemp lime products have been used to construct a number of non-housing projects including a seven-storey office building (Regional Government Office of Housing and Environment, Clermont Ferrand) for the French government and several other projects including significant rehabilitations of older buildings.

Fig 1.1:

1 INTRODUCTION

l.S AN OUTLINE OFHEMPLIME CONSTRUCTION The most typical form of hemp lime construction uses conventional timber frames with panels constructed of timber studs, and the hemp lime cast around the frame to create a solid wall. There is often no need to use timber sheathing boards, breather membranes, internal finishes like plasterboard and external cladding which can make normal timber frame construction rather complicated. The hemp lime provides a solid wall, acoustic and thermal insulation, and even an internal finish. Weather protection of the hemp lime is needed to shed precipitation and this can be provided by different finishes, including lime render, lapped timber boards, shingles, rainscreen tiles or lime-mortared brickwork. This uncomplicated method can reduce labour costs, speed up construction and simplify the building process.

The UK construction industry tends to exhibit a deeply conservative suspicion of unfamiliar building methods yet shows a surprising willingness to take on some new untried technological methods if they look cheaper and quicker. In order for hemp lime to be adopted it has to prove to a sceptical audience

Seven-storeyoffice building in Clermont Ferrandwhich useshemp lime blocks

of architects, builders and clients that it can meet Building Regulations and current new sustainability standards, and can also be technically approved, insurance approved, and affordable.

1.6 METHODOLOGY OFTHESTUDY The study for the NNFCC consisted of gathering as much information as possible about hemp construction and visiting many of the UK hemp construction projects. We attended a wide range of meetings organised by businesses in the sector including several research-based seminars with participants from France and Belgium. We interviewed architects, builders, timber frame manufacturers and material manufacturers. We assembled a team of experts to look at issues such as structural engineering, detail design, life cycle assessment (LCA), and specification and thermal performance.

During the course of the study a trade association, the Hemp Lime Construction Products Association (www.hemplime.org.uk), was established and a UK-based supply chain for production and distribution of materials was also set up. We were able to observe this process and also meet with new industrial participants from the mainstream construction industry. Large stands promoting hemp construction were built at the Ecobuild exhibition at Earls Court in London in February 2006 and February 2007 and several hemp lime training sessions have been held around the UK. This made it possible to meet with potential designers and specifiers of the material and to listen to their questions and concerns. The market is currently dominated by a small group of companies who have developed strong commercial ties but there are a few other suppliers of materials and competition is likely to grow as the material becomes more widely adopted.

While this has essentially been a desk-based study, we were able to carry out some thermal testing in order to check data and claims that might have been difficult to substantiate. We have also been able to observe and monitor a few hemp building projects under construction and have built a small model of a section of a building. We have

been given privileged access to results of building tests carried out by others both onsite and at the University of Bath, University of Plymouth and the National Physical Laboratory.

1.7

PERFORMANCE OFHEMPLIME

An interesting finding of the study is that current conventional methods for the testing and rating of insulating materials and building methods do not favour natural materials. Thus performance predicted by such methods may be exceeded in practice.

This raises a number of fundamental questions about existing methods of building science that are used to assessmaterials and building methods.

Current methods of testing and evaluating building materials, particularly in terms of thermal performance, must be questioned as they have been largely designed for lightweight synthetic materials with an assumption of steady-state conditions. Evidence suggeststhat hemp lime walls perform significantly better than would be predicted from conventional U-value figures. This created difficulties when BREevaluated the thermal performance of two hemp houses in Haverhill in Suffolk in 2001-2. These houses were compared with two identical houses of brick and block that used 100 mm of blown fibre Rockwool cavity fill insulation (BRE, 2002).

BRE found that the two hemp houses were functioning with lower heating bills at a temperature of 1 or 2 degrees higher than the control houses. This confirmed the suspicion that the conventional method of evaluating theoretical thermal efficiency, which predicted a poorer performance for the hemp houses, was wrong in practice. This is due to testing methods being designed for lightweight materials that are normally tested in a 'hot box'. This method does not take account of the ability of materials to store heat and absorb moisture, both of which affect thermal performance in practice. In order to demonstrate that hemp construction can provide better thermal performance than conventional materials it will be necessary to carry out a further series of tests of buildings once constructed and over a period of time and compare them with

-

HEMP LIME CONSTRUCTION

identical buildings using other materials. It is also clear that other factors can play a part in improved thermal performance in that hemp construction makes it possible to create very airtight buildings, whereas conventional construction methods often create leakier buildings owing to the complexity of the combination of many materials and layers.

Research investigating these issues is being carried out at the University of Plymouth, the University of Bath, the Centre for Alternative Technology and . the Universite catholique de Louvain in Belgium.

1.8 SUPPLY OFHEMPMATERIALS FOR CONSTRUCTION Hemp has enjoyed a revival·of interest in recent years. Hemp growing was made illegal in the US and UK in the 1950s due to the association of the plant with the drug cannabis or marijuana.

Industrial hemp crops contain only tiny traces of what is known as THC, which is responsible for the narcotic effects of marijuana. However, numerous conspiracy theorists have claimed that this link was exploited by the manufacturers of synthetic fibres like nylon to suppress the growing of hemp. Despite this, hemp continued to be grown in Europe, particularly for paper production, and it was revived in the UK in the early 1 990s.

Hemcore, the leading UK hemp processor, was granted its first licence to grow hemp in 1993. In 2006, 5000 tonnes of hemp were processed in the UK, from about 1300 hectares.

Fibre extracted is exported to Germany where it is used by the automobile industry for car interiors and some fibre is also used for hemp insulation quilts. The shiv or hurd (the straw waste from the fibre) has been sold for a number of years as high quality horse bedding but is increasingly being used for construction. We understand that Hemcore can only just meet the demand for its hemp and foresee an expansion of hemp cultivation to 7000 acres by 2010. The company is investing in a new processing factory that will lead to over 50,000 tonnes being processed.

Currently Hemcore dominates the UK market and there are no other significant processors.

Manufacture of hemp products has been more

!INTRODUCTION -

significant in Germany because of government support. Hemp is now being grown in Poland as well as France, where it has been grown for paper production for many years.

A conventional house built with hemp lime would require about 40 cubic metres of hemp lime mixture. The hemp for this would require about 1 hectare of land to grow, yielding about 7-1 O tonnes of hemp. If 180,000 houses in the UK were built with hemp (an unlikely scenario!) this would require 180,000 hectares, which is equivalent to roughly 30% of all the set-aside land in the UK. Hemp can be grown as a break crop between cereals or potato crops and has many advantages for farmers, suppressing weeds and improving the ground. It is relatively easy to grow with care and the risks are more in the harvesting and processing.

Hemcore (www.hemcore.co.uk), based in Essex,have been working closely with Lime Technology Ltd (www.limetechnology. co.uk) and Lhoist UK (www.lhoist.co.uk) to promote a proprietary brand (Tradical) for what they have called 'hemcrete' construction.

Lime Technology Ltd has set up a factory in Abingdon, Oxfordshire, where the Tradical lime binder is being manufactured. This means that these companies can offer the supply of UK manufactured materials whereas previously the technology and materials were imported from France. Lime Technology Ltd uses the registered name Hemcrete but the hemp shiv aggregate and the lime binder are now referred to as Tradical products.

It is possible to produce satisfactory hemp lime construction mixing hemp shiv and lime binders that have not been supplied by this new commercial consortium. The Haverhill project referred to above was built using 'mineralised' hemp from a French company called lsochanvre (which no longer exists) and natural hydraulic lime (NHL). However, great care needs to be taken to ensure that the correct mix is used if hemp lime (made with NHL) is to be successful and in a number of examples of buildings in Ireland there have been problems, particularly with moisture, where builders have been making up their own mixes. The main advantage of using the Tradical products is the predictability of

the results (providing instructions are followed) and the professional service offered. However, there are also commercial NHL-based products available from other French companies such as St Astier (www.stastier.co.uk) and these are available through UK stockists.

The Hemp Lime Construction Products Association (www.hemplime.org.uk) is intended to be a broad-based organisation for all manufacturers and suppliers in the field and has also begun to involve companies from the UK Sprayed Concrete Association who are able to apply hemp lime to buildings. In the longer term hemp may be grown throughout the UK, with a range of processors, suppliers and stockists of the shive and lime binders. Much of the information about how much material is being sold is commercially sensitive but it has been estimated that over 10,000 m3 of hemp lime is likely to be used in 2008.

1.9

GLOSSARY OFTERMS

Batichanvre: Registered name for St Astier hemp

lime products.

Hemp lime, hemcrete, hempcrete, lime hemp, hemp lime composite: All refer to a mix of hemp lime with

water which can be cast or sprayed into a solid wall, floor or roof. We have tried to be consistent in using the term 'hemp lime' in this book.

Hemcrete: Proprietary product (registered) for

hempcrete.

Kena(: Plant, similar to hemp, mainly grown in tropical regions.

Lime binder: An appropriate mix of lime and other

additives that is mixed with hemp.

Shiv, shive or hurd: The chopped straw of the plant

after the fibre has been extracted.

Tradical: Registered name for a range of hemp lime

products.

Fig 1.2:

Interior of the Adnarns brewery warehouse, Suffolk

-

HEMP LIME CONSTRUCTION

identical buildings using other materials. It is also clear that other factors can play a part in improved thermal performance in that hemp construction makes it possible to create very airtight buildings, whereas conventional construction methods often create leakier buildings owing to the complexity of the combination of many materials and layers.

Research investigating these issues is being carried out at the University of Plymouth, the University of Bath, the Centre for Alternative Technology and . the Universite catholique de Louvain in Belgium.

1.8 SUPPLY OFHEMPMATERIALS FOR CONSTRUCTION Hemp has enjoyed a revival·of interest in recent years. Hemp growing was made illegal in the US and UK in the 1950s due to the association of the plant with the drug cannabis or marijuana.

Industrial hemp crops contain only tiny traces of what is known as THC, which is responsible for the narcotic effects of marijuana. However, numerous conspiracy theorists have claimed that this link was exploited by the manufacturers of synthetic fibres like nylon to suppress the growing of hemp. Despite this, hemp continued to be grown in Europe, particularly for paper production, and it was revived in the UK in the early 1 990s.

Hemcore, the leading UK hemp processor, was granted its first licence to grow hemp in 1993. In 2006, 5000 tonnes of hemp were processed in the UK, from about 1300 hectares.

Fibre extracted is exported to Germany where it is used by the automobile industry for car interiors and some fibre is also used for hemp insulation quilts. The shiv or hurd (the straw waste from the fibre) has been sold for a number of years as high quality horse bedding but is increasingly being used for construction. We understand that Hemcore can only just meet the demand for its hemp and foresee an expansion of hemp cultivation to 7000 acres by 2010. The company is investing in a new processing factory that will lead to over 50,000 tonnes being processed.

Currently Hemcore dominates the UK market and there are no other significant processors.

Manufacture of hemp products has been more

!INTRODUCTION -

significant in Germany because of government support. Hemp is now being grown in Poland as well as France, where it has been grown for paper production for many years.

A conventional house built with hemp lime would require about 40 cubic metres of hemp lime mixture. The hemp for this would require about 1 hectare of land to grow, yielding about 7-1 O tonnes of hemp. If 180,000 houses in the UK were built with hemp (an unlikely scenario!) this would require 180,000 hectares, which is equivalent to roughly 30% of all the set-aside land in the UK. Hemp can be grown as a break crop between cereals or potato crops and has many advantages for farmers, suppressing weeds and improving the ground. It is relatively easy to grow with care and the risks are more in the harvesting and processing.

Hemcore (www.hemcore.co.uk), based in Essex,have been working closely with Lime Technology Ltd (www.limetechnology. co.uk) and Lhoist UK (www.lhoist.co.uk) to promote a proprietary brand (Tradical) for what they have called 'hemcrete' construction.

Lime Technology Ltd has set up a factory in Abingdon, Oxfordshire, where the Tradical lime binder is being manufactured. This means that these companies can offer the supply of UK manufactured materials whereas previously the technology and materials were imported from France. Lime Technology Ltd uses the registered name Hemcrete but the hemp shiv aggregate and the lime binder are now referred to as Tradical products.

It is possible to produce satisfactory hemp lime construction mixing hemp shiv and lime binders that have not been supplied by this new commercial consortium. The Haverhill project referred to above was built using 'mineralised' hemp from a French company called lsochanvre (which no longer exists) and natural hydraulic lime (NHL). However, great care needs to be taken to ensure that the correct mix is used if hemp lime (made with NHL) is to be successful and in a number of examples of buildings in Ireland there have been problems, particularly with moisture, where builders have been making up their own mixes. The main advantage of using the Tradical products is the predictability of

the results (providing instructions are followed) and the professional service offered. However, there are also commercial NHL-based products available from other French companies such as St Astier (www.stastier.co.uk) and these are available through UK stockists.

The Hemp Lime Construction Products Association (www.hemplime.org.uk) is intended to be a broad-based organisation for all manufacturers and suppliers in the field and has also begun to involve companies from the UK Sprayed Concrete Association who are able to apply hemp lime to buildings. In the longer term hemp may be grown throughout the UK, with a range of processors, suppliers and stockists of the shive and lime binders. Much of the information about how much material is being sold is commercially sensitive but it has been estimated that over 10,000 m3 of hemp lime is likely to be used in 2008.

1.9

GLOSSARY OFTERMS

Batichanvre: Registered name for St Astier hemp

lime products.

Hemp lime, hemcrete, hempcrete, lime hemp, hemp lime composite: All refer to a mix of hemp lime with

water which can be cast or sprayed into a solid wall, floor or roof. We have tried to be consistent in using the term 'hemp lime' in this book.

Hemcrete: Proprietary product (registered) for

hempcrete.

Kena(: Plant, similar to hemp, mainly grown in tropical regions.

Lime binder: An appropriate mix of lime and other

additives that is mixed with hemp.

Shiv, shive or hurd: The chopped straw of the plant

after the fibre has been extracted.

Tradical: Registered name for a range of hemp lime

products.

Fig 1.2:

Interior of the Adnarns brewery warehouse, Suffolk

2 WHAT ISHEMP CONSTllUCTION?

2 WHATIS HEMP CONSTRUCTION? Hemp lime is a 'novel' construction material.

The composite material combines fast-growing renewable and carbon sequestrating plant-based aggregates (hemp shiv) with a lime-based binder to form a lightweight material that is suited to various construction applications, including solid walls, roof insulation and under-floor insulation and as part of timber-framed building. It also offers good thermal and acoustic performance and the ability to regulate internal relative humidity through hygroscopic material behaviour, contributing to healthier building spaces and providing effective thermal mass.

A lightweight hemp lime composite is formed by mixing together hemp shiv and a lime-based binder.

The lime binds the hemp aggregatestogether, giving the material modest structural strength and stiffness.

Lime also protects the shiv from biological decay, mainly through its ability to wick water away from the hemp shiv and its high alkalinity, as well as providing essential fire resistance. Hemp lime can be used to form solid non-load-bearing panels, typically as part of timber or other framed buildings. By varying the mix design, hemp lime materials may also be used in denser or lighter composites for floor insulation and roof insulation.

Hemp lime has been under development since the early 1990s, mainly through work in France and Belgium, but also work completed in the UK funded

by Defra, NNFCC and DTI. Pioneering building projects in the UK include houses in Haverhill, and Adnams brewery near Southwold in Suffolk and Lime Technology Ltd's offices in Abingdon, Oxfordshire.

A number of studies have shown that hemp lime has good thermal and acoustic insulation properties. The lightweight hemp lime absorbs sound, dampening transmission through walls and other elements. It also provides an innovative way of

meeting the increasingly stringent thermal insulation requirements of the Building Regulations.

The carbon sequestration and storage capacity of hemp lime is a significant benefit of the material.

As government policy becomes increasingly concerned with reducing carbon emissions and finding more efficient ways of meeting current targets, hemp lime can make a major contribution to this, offering a genuinely zero-carbon contribution to sustainable construction policies.

2.1

NON-FOOD CROPS

Natural fibres and crop-based materials are being widely used in building construction today. Timber has been used since the beginning of time and is a natural crop-based material. However, good quality construction timber takes a long time to grow and it has been recognised for some time that the forests of the world are vital in terms of maintaining ecological balance. Thus timber is a valuable resource that should be used responsibly in any sustainable building. Cellulose for building can be obtained from a variety of sources, not just timber, and a range of crop-based materials have recently emerged as viable alternatives to synthetic and fossil-fuel-based products. Non-food crops can be the basis of many requirements, the best known of which currently are bio-fuels. Using crops that can be grown annually provides a source of material that can be replaced each year and grown as part of a well-managed agricultural system. There is growing opposition to the use of food crops like wheat for bio-fuels because this has increased the price of food, but there is unlikely to be protest about non-food crops as they help with agricultural diversification. Crops like hemp can be grown in rotation with food crops to improve the soil and reduce weeds.

2 WHAT ISHEMP CONSTllUCTION?

2 WHATIS HEMP CONSTRUCTION? Hemp lime is a 'novel' construction material.

The composite material combines fast-growing renewable and carbon sequestrating plant-based aggregates (hemp shiv) with a lime-based binder to form a lightweight material that is suited to various construction applications, including solid walls, roof insulation and under-floor insulation and as part of timber-framed building. It also offers good thermal and acoustic performance and the ability to regulate internal relative humidity through hygroscopic material behaviour, contributing to healthier building spaces and providing effective thermal mass.

A lightweight hemp lime composite is formed by mixing together hemp shiv and a lime-based binder.

The lime binds the hemp aggregatestogether, giving the material modest structural strength and stiffness.

Lime also protects the shiv from biological decay, mainly through its ability to wick water away from the hemp shiv and its high alkalinity, as well as providing essential fire resistance. Hemp lime can be used to form solid non-load-bearing panels, typically as part of timber or other framed buildings. By varying the mix design, hemp lime materials may also be used in denser or lighter composites for floor insulation and roof insulation.

Hemp lime has been under development since the early 1990s, mainly through work in France and Belgium, but also work completed in the UK funded

by Defra, NNFCC and DTI. Pioneering building projects in the UK include houses in Haverhill, and Adnams brewery near Southwold in Suffolk and Lime Technology Ltd's offices in Abingdon, Oxfordshire.

A number of studies have shown that hemp lime has good thermal and acoustic insulation properties. The lightweight hemp lime absorbs sound, dampening transmission through walls and other elements. It also provides an innovative way of

meeting the increasingly stringent thermal insulation requirements of the Building Regulations.

The carbon sequestration and storage capacity of hemp lime is a significant benefit of the material.

As government policy becomes increasingly concerned with reducing carbon emissions and finding more efficient ways of meeting current targets, hemp lime can make a major contribution to this, offering a genuinely zero-carbon contribution to sustainable construction policies.

2.1

NON-FOOD CROPS

Natural fibres and crop-based materials are being widely used in building construction today. Timber has been used since the beginning of time and is a natural crop-based material. However, good quality construction timber takes a long time to grow and it has been recognised for some time that the forests of the world are vital in terms of maintaining ecological balance. Thus timber is a valuable resource that should be used responsibly in any sustainable building. Cellulose for building can be obtained from a variety of sources, not just timber, and a range of crop-based materials have recently emerged as viable alternatives to synthetic and fossil-fuel-based products. Non-food crops can be the basis of many requirements, the best known of which currently are bio-fuels. Using crops that can be grown annually provides a source of material that can be replaced each year and grown as part of a well-managed agricultural system. There is growing opposition to the use of food crops like wheat for bio-fuels because this has increased the price of food, but there is unlikely to be protest about non-food crops as they help with agricultural diversification. Crops like hemp can be grown in rotation with food crops to improve the soil and reduce weeds.

HEMP LIME CONSTRUCTION

Hemp is one of the most important non-food crops but others include flax, miscanthus, and fast growing trees like willow. Cotton and sheep's wool are also used in construction. Hemp is grown for fibre, which is used in bio-composites and insulation quilts. It is also used for seed to produce oils that are used in a number of applications including cosmetics and foodstuffs. The stalk of the plant, normally known as the hurd or shiv, was seen as a waste by-product and has been sold for many years .. as horse-bedding to stables and farms. However, it was realised that the shiv could be used to produce a unique building material.

When hemp is harvested the plant is left to 'ret' on the ground for three to four weeks. The stalks are baled and taken to the processing factory where the fibre is stripped off (de-cortification), leaving the woody core or stalk behind. This can be chopped up into small lengths and used as a kind of natural aggregate. Mixing the hemp shiv with lime-based binders produces a form of lightweight concrete, which has a number of attractive properties that are dealt with in more detail below.

2.2

HEMPCRETE ORHEMPLIME?

Mixing the hemp shiv and lime with water creates the lightweight lime and hemp mixture that is sometimes referred to by the generic term hempcrete. The proportions of the hemp lime can be varied according to the density and characteristics required. Suppliers of proprietary hemp lime materials will indicate the correct mix proportions of lime binder to hemp.

Once the material is mixed with a small amount of water it resembles a sticky porridge that can be cast into walls, roofs or floors to produce a solid insulating mass. This mass is solid enough to hold together quite quickly but then takes a while to dry out and cure.

Drying and curing time will vary according to the mix, climatic conditions and so on, but is normally about four weeks. This may seem like a disadvantage when so many building methods offer quick-fix solutions. However, the hemp lime mix is solid almost as soon as it is cast and shuttering can be removed immediately or after 24 hours.

There are various ways in which hemp lime can be used. It can either be cast like concrete within shuttering or sprayed. It can be used as a plaster or cast as a floor screed. It can be cast into blocks or panels. In France it is common to spray hemp lime 'as a roofing slab onto a permanent sloping ceiling board. It could also be used as ceiling insulation but this is uncommon. It is a very versatile material because it can be used in so many different ways.

When the material has dried out it becomes a strong and solid composite which creates a weatherproof mass providing thermal insulation, thermal storage and a substrate, that can take a variety of finishes. The different ways in which hemp lime can be placed and used are described in more detail in later chapters.

When building walls, the normal practice is to construct a simple timber frame which provides the principal structure of the building supporting any floors and roofs. The hemp lime is then sprayed or cast around the timber frame to provide solid walls, and possibly floors and roof.

As well as being used for new construction, hemp lime can be used for the renovation and repair of old timber-framed buildings as a sympathetic replacement for the original wall infill or as an insulating plaster on old masonry.

2.3

Fig 2. 1:

Hemp shiv with lime being mixed

CONSTRUCTION OFWALLS

A hemp lime composite wall is not usually a loadbearing element. It is normally cast around a frame and relies on the frame to carry the structural loads of the roof and upper floors down to the foundations and ground. It does, however, provide some racking strength for the frame, which may not need additional bracing. It can be cast around the timber frame with timber studs placed centrally or closer to either the inner or outer wall face. This provides a natural protective environment for the timber and there may be no need for additional chemical treatments. Where the timber frame will be used to fix permanent shuttering or other finishes it may be necessaryto move the timber frame to the edge of the wall thickness. Some designers may prefer to use chemical timber treatments if the timber is exposed to the outside or used with a rainscreen cladding.

Fig 2.2: Timber frame and hemp lime infill being tamped by school children. Hemp lime is 'child's play'

The hemp lime is usually mixed onsite by blending the hemp filler with the lime binder.

It is important to achieve efficient mixing and to fully coat the hemp shiv with the lime binder. Mixing is best done with a pan mixer or machine-mounted mixing bucket, adding water as required. The mix can then be poured into temporary or permanent shuttering and lightly tamped into place.

It is normal to tamp the material in vertical layers 200 mm to 300 mm thick. Alternatively the mix can be sprayed using a modified dry spray concrete system against single-sided shuttering (temporary or permanent) and then ruled flat. Usually the shuttering is left in place for 24 hours before removing it, although the material quickly achieves a self-supporting resilience and the shuttering can be removed earlier.

HEMP LIME CONSTRUCTION

Hemp is one of the most important non-food crops but others include flax, miscanthus, and fast growing trees like willow. Cotton and sheep's wool are also used in construction. Hemp is grown for fibre, which is used in bio-composites and insulation quilts. It is also used for seed to produce oils that are used in a number of applications including cosmetics and foodstuffs. The stalk of the plant, normally known as the hurd or shiv, was seen as a waste by-product and has been sold for many years .. as horse-bedding to stables and farms. However, it was realised that the shiv could be used to produce a unique building material.

When hemp is harvested the plant is left to 'ret' on the ground for three to four weeks. The stalks are baled and taken to the processing factory where the fibre is stripped off (de-cortification), leaving the woody core or stalk behind. This can be chopped up into small lengths and used as a kind of natural aggregate. Mixing the hemp shiv with lime-based binders produces a form of lightweight concrete, which has a number of attractive properties that are dealt with in more detail below.

2.2

HEMPCRETE ORHEMPLIME?

Mixing the hemp shiv and lime with water creates the lightweight lime and hemp mixture that is sometimes referred to by the generic term hempcrete. The proportions of the hemp lime can be varied according to the density and characteristics required. Suppliers of proprietary hemp lime materials will indicate the correct mix proportions of lime binder to hemp.

Once the material is mixed with a small amount of water it resembles a sticky porridge that can be cast into walls, roofs or floors to produce a solid insulating mass. This mass is solid enough to hold together quite quickly but then takes a while to dry out and cure.

Drying and curing time will vary according to the mix, climatic conditions and so on, but is normally about four weeks. This may seem like a disadvantage when so many building methods offer quick-fix solutions. However, the hemp lime mix is solid almost as soon as it is cast and shuttering can be removed immediately or after 24 hours.

There are various ways in which hemp lime can be used. It can either be cast like concrete within shuttering or sprayed. It can be used as a plaster or cast as a floor screed. It can be cast into blocks or panels. In France it is common to spray hemp lime 'as a roofing slab onto a permanent sloping ceiling board. It could also be used as ceiling insulation but this is uncommon. It is a very versatile material because it can be used in so many different ways.

When the material has dried out it becomes a strong and solid composite which creates a weatherproof mass providing thermal insulation, thermal storage and a substrate, that can take a variety of finishes. The different ways in which hemp lime can be placed and used are described in more detail in later chapters.

When building walls, the normal practice is to construct a simple timber frame which provides the principal structure of the building supporting any floors and roofs. The hemp lime is then sprayed or cast around the timber frame to provide solid walls, and possibly floors and roof.

As well as being used for new construction, hemp lime can be used for the renovation and repair of old timber-framed buildings as a sympathetic replacement for the original wall infill or as an insulating plaster on old masonry.

2.3

Fig 2. 1:

Hemp shiv with lime being mixed

CONSTRUCTION OFWALLS

A hemp lime composite wall is not usually a loadbearing element. It is normally cast around a frame and relies on the frame to carry the structural loads of the roof and upper floors down to the foundations and ground. It does, however, provide some racking strength for the frame, which may not need additional bracing. It can be cast around the timber frame with timber studs placed centrally or closer to either the inner or outer wall face. This provides a natural protective environment for the timber and there may be no need for additional chemical treatments. Where the timber frame will be used to fix permanent shuttering or other finishes it may be necessaryto move the timber frame to the edge of the wall thickness. Some designers may prefer to use chemical timber treatments if the timber is exposed to the outside or used with a rainscreen cladding.

Fig 2.2: Timber frame and hemp lime infill being tamped by school children. Hemp lime is 'child's play'

The hemp lime is usually mixed onsite by blending the hemp filler with the lime binder.

It is important to achieve efficient mixing and to fully coat the hemp shiv with the lime binder. Mixing is best done with a pan mixer or machine-mounted mixing bucket, adding water as required. The mix can then be poured into temporary or permanent shuttering and lightly tamped into place.

It is normal to tamp the material in vertical layers 200 mm to 300 mm thick. Alternatively the mix can be sprayed using a modified dry spray concrete system against single-sided shuttering (temporary or permanent) and then ruled flat. Usually the shuttering is left in place for 24 hours before removing it, although the material quickly achieves a self-supporting resilience and the shuttering can be removed earlier.

HEMP LIME CONSTRUCTION

Construction with hemp lime is not recommended when temperatures are below S C. It needs to be protected from extremes of weather while it is setting, and from rising dampness by a masonry plinth containing a damp-proof course. It can be protected from falling rain by an adequate roof overhang at the top of the wall. The hemp lime wall also needs external weather protection provided by a finishing material - such as a lime render, timber rainscreen or other protection providing that it has vapour permeability and allows the hemp lime composite to breathe.

These sensible precautions are an essential part of normal good masonry building practice and do not indicate any unusual limitations of the material.

Hemp lime has proved to be very robust in most temperate weather conditions.

0

2.4

TIMBER FRAME

Those specifying conventional timber frame construction will be aware that timber frame buildings have to be clad in a variety of materials, timber boarding, or even masonry such as brick or blockwork on the outside. The build-up of timber frame construction is quite complex and requires breather membranes, the external cladding must be attached to the frame and insulation must be inserted with internal finishing boards.

Hemp lime cast around a timber frame simplifies this considerably and requires fewer trades and processes.

This makes construction much less complicated: it ensures better quality and robustness and saves money by reducing trades. The detailing of hemp lime with timber frames is very simple and can be seen in the drawings and photographs included in this book. Timber frame construction has not yet been entirely accepted by the construction industry or the general public as there remain prejudices

about fire safety, potential for rot and the lightweight nature of timber buildings, yet it is one of the fastest-growing sectors. Hemp lime construction, when used with timber frame, significantly reduces risks with fire, damp and rot and adds effective thermal mass to the construction.

2.S

BLOCKMAKING

Hemp lime can also be cast into blocks and for certain kinds of buildings this may be more appropriate than casting it as a solid mass. Many people new to hemp lime assume that it will be used for blocks but this is generally a more expensive way of using the material. A number of examples where blocks have been used are shown in the case studies. The blocks normally require a mortar bed of lime and sand and the overall wall will have different structural characteristics to one cast as a solid mass. Block walls are denser and thus will not have such good thermal insulation properties but will provide excellent thermal mass.

Hemp lime blocks can be used to build solid walls or used as infill inside a frame construction.

A seven-storey building in France has been constructed using block infill in a concrete frame (see Figs 1 .1 and 10.1 ). Normally the blocks do not have sufficient strength to be used like conventional concrete blocks though future experiments may produce stronger blocks incorporating fibre as well as shiv.

Tradical Hemcrete blocks are being made to a compressive strength of 3 N/mm 2 although this is

Fig 2.3:

Hemp lime blocks

Fig 2.4:

Hemp lime block wall in French office building

achieved through the use of a higher proportion of binder and some aggregate (sand). Blocks may be appropriate for conservation work and have been inserted into old timber frames. A company near Leipzig in Germany makes bricks from hemp and clay for conservation work.

HEMP LIME CONSTRUCTION

Construction with hemp lime is not recommended when temperatures are below S C. It needs to be protected from extremes of weather while it is setting, and from rising dampness by a masonry plinth containing a damp-proof course. It can be protected from falling rain by an adequate roof overhang at the top of the wall. The hemp lime wall also needs external weather protection provided by a finishing material - such as a lime render, timber rainscreen or other protection providing that it has vapour permeability and allows the hemp lime composite to breathe.

These sensible precautions are an essential part of normal good masonry building practice and do not indicate any unusual limitations of the material.

Hemp lime has proved to be very robust in most temperate weather conditions.

0

2.4

TIMBER FRAME

Those specifying conventional timber frame construction will be aware that timber frame buildings have to be clad in a variety of materials, timber boarding, or even masonry such as brick or blockwork on the outside. The build-up of timber frame construction is quite complex and requires breather membranes, the external cladding must be attached to the frame and insulation must be inserted with internal finishing boards.

Hemp lime cast around a timber frame simplifies this considerably and requires fewer trades and processes.

This makes construction much less complicated: it ensures better quality and robustness and saves money by reducing trades. The detailing of hemp lime with timber frames is very simple and can be seen in the drawings and photographs included in this book. Timber frame construction has not yet been entirely accepted by the construction industry or the general public as there remain prejudices

about fire safety, potential for rot and the lightweight nature of timber buildings, yet it is one of the fastest-growing sectors. Hemp lime construction, when used with timber frame, significantly reduces risks with fire, damp and rot and adds effective thermal mass to the construction.

2.S

BLOCKMAKING

Hemp lime can also be cast into blocks and for certain kinds of buildings this may be more appropriate than casting it as a solid mass. Many people new to hemp lime assume that it will be used for blocks but this is generally a more expensive way of using the material. A number of examples where blocks have been used are shown in the case studies. The blocks normally require a mortar bed of lime and sand and the overall wall will have different structural characteristics to one cast as a solid mass. Block walls are denser and thus will not have such good thermal insulation properties but will provide excellent thermal mass.

Hemp lime blocks can be used to build solid walls or used as infill inside a frame construction.

A seven-storey building in France has been constructed using block infill in a concrete frame (see Figs 1 .1 and 10.1 ). Normally the blocks do not have sufficient strength to be used like conventional concrete blocks though future experiments may produce stronger blocks incorporating fibre as well as shiv.

Tradical Hemcrete blocks are being made to a compressive strength of 3 N/mm 2 although this is

Fig 2.3:

Hemp lime blocks

Fig 2.4:

Hemp lime block wall in French office building

achieved through the use of a higher proportion of binder and some aggregate (sand). Blocks may be appropriate for conservation work and have been inserted into old timber frames. A company near Leipzig in Germany makes bricks from hemp and clay for conservation work.

HEMP LIME CONSTRUCTION

2.6

FINISHES ANDSPRAYING

Hemp lime walls can easily be finished with a simple render or plaster on the inside and outside and lime is usually recommended for this as it has good vapour permeability which is essential for the hygrothermal performance of hemp lime. The outer render will provide weather protection. If hemp lime is cast carefully it may not be necessary to plaster it internally - there are many examples where hemp lime walls have been left unplastered. Some find the texture attractive and it also provides very good acoustic absorbency.

If hemp lime walls are constructed using spraying techniques onsite, one option is to use permanent shuttering against which the mix can be sprayed. A number of different shuttering techniques and materials can be used for this but they must be able to cope with the amount of moisture in the mix. Spraying requires specialist equipment and it is best if trained operatives are employed to carry out this work.

Both external and internal finishes should be breathable (micro-porous) and it does not make sense to apply a plastic/polymer-based paint or other finishes which may compromise the breathability and durability of the material.

2.7

RENOVATING EXISTING BUILDINGS

Hemp lime can be used as an insulating plaster on the inside or outside of existing walls and as an insulating screed on existing floors. It has been used successfully on building interiors and exteriors. The mix adheres to most materials, steel, brick, concrete, old plaster and render, and wood. It may not stick so easily to plastic and synthetic materials. A big potential for the material is as an insulating plaster in the renovation of old buildings where it is not sensible to use dry lining and where other materials will not cope with dampness when applied to old walls. However, not enough data are yet available to give a firm indication of the thermal performance of such work.

Hemp lime was first used in the renovation of historic buildings, particularly those with timber frames, and it is now often used in conservation work throughout Europe. The main purpose of this is to replace old wattle and daub of lime, mud straw and horse hair with a modern material. Hemp and lime has proved to be flexible and robust with very little shrinkage when it dries out and yet, being a natural material it works in harmony with the ancient wood frames.

2.8 SOURCING MATERIALS ANDDIY

Fig 2.5:

Hemp lime being sprayed at the Lime Technology Ltd head office building

Hemp lime materials can be obtained from a number of sources. They are commercially available from a range of building materials stockists. In the future it may be possible to order ready-mix hemp lime, in a similar way to the ordering of lime mortar in silos, which can be set up on construction sites.

However, care will need to be taken to reduce the natural humidity levels in the shiv; this could cause the hydration of the binder and thus, in the short term at least, it will be necessary to mix the materials at the point of use while following the manufacturer's instructions.

Sourcing the materials in bulk is desirable for maximising the efficiency of hemp lime use if it is to be adopted by the mainstream construction industry. Meanwhile, the establishment of a reliable supply chain and predictable performance with technical back-up and advice are the key essentials if the mainstream construction industry is to adopt the technology.

Hemp lime infill being used to renovate an historic timber frame house

Fig 2.6:

HEMP LIME CONSTRUCTION

2.6

FINISHES ANDSPRAYING

Hemp lime walls can easily be finished with a simple render or plaster on the inside and outside and lime is usually recommended for this as it has good vapour permeability which is essential for the hygrothermal performance of hemp lime. The outer render will provide weather protection. If hemp lime is cast carefully it may not be necessary to plaster it internally - there are many examples where hemp lime walls have been left unplastered. Some find the texture attractive and it also provides very good acoustic absorbency.

If hemp lime walls are constructed using spraying techniques onsite, one option is to use permanent shuttering against which the mix can be sprayed. A number of different shuttering techniques and materials can be used for this but they must be able to cope with the amount of moisture in the mix. Spraying requires specialist equipment and it is best if trained operatives are employed to carry out this work.

Both external and internal finishes should be breathable (micro-porous) and it does not make sense to apply a plastic/polymer-based paint or other finishes which may compromise the breathability and durability of the material.

2.7

RENOVATING EXISTING BUILDINGS

Hemp lime can be used as an insulating plaster on the inside or outside of existing walls and as an insulating screed on existing floors. It has been used successfully on building interiors and exteriors. The mix adheres to most materials, steel, brick, concrete, old plaster and render, and wood. It may not stick so easily to plastic and synthetic materials. A big potential for the material is as an insulating plaster in the renovation of old buildings where it is not sensible to use dry lining and where other materials will not cope with dampness when applied to old walls. However, not enough data are yet available to give a firm indication of the thermal performance of such work.

Hemp lime was first used in the renovation of historic buildings, particularly those with timber frames, and it is now often used in conservation work throughout Europe. The main purpose of this is to replace old wattle and daub of lime, mud straw and horse hair with a modern material. Hemp and lime has proved to be flexible and robust with very little shrinkage when it dries out and yet, being a natural material it works in harmony with the ancient wood frames.

2.8 SOURCING MATERIALS ANDDIY

Fig 2.5:

Hemp lime being sprayed at the Lime Technology Ltd head office building

Hemp lime materials can be obtained from a number of sources. They are commercially available from a range of building materials stockists. In the future it may be possible to order ready-mix hemp lime, in a similar way to the ordering of lime mortar in silos, which can be set up on construction sites.

However, care will need to be taken to reduce the natural humidity levels in the shiv; this could cause the hydration of the binder and thus, in the short term at least, it will be necessary to mix the materials at the point of use while following the manufacturer's instructions.

Sourcing the materials in bulk is desirable for maximising the efficiency of hemp lime use if it is to be adopted by the mainstream construction industry. Meanwhile, the establishment of a reliable supply chain and predictable performance with technical back-up and advice are the key essentials if the mainstream construction industry is to adopt the technology.

Hemp lime infill being used to renovate an historic timber frame house

Fig 2.6:

HEMP LIME CONSTRUCTION

Fig 2.7:

Lime mortar silo

There has been considerable investment in France, Belgium and the UK to develop the technology so that materials can be supplied in bulk.

Of course it will still be possible for small builders to order small amounts of the materials and construct more modest buildings. Materials should be available from builders' merchants before too long and can be ordered directly from the manufacturers in the meantime. Small-scale hand-crafted hemp lime buildings will still be a key part of the natural building sector.

Pioneering architect Ralph Carpenter, based in Suffolk, uses his own mixture of lime binder and has achieved good results with hemp lime buildings, but he takes great care and has a great deal of experience.

2 WHAT ISHEMP CONSTRUCTION? -

Self-builders may feel that they can manage to grow their own hemp and find some lime binder to produce buildings without going to mainstream suppliers*. A number of people have done this in the early experimental stages and even today some think that this will save them money. For small projects the savings in using non-proprietary hemp lime binder products is likely to be marginal and the risks of making up your own mix can be great.

Even if permission is sought to grow some hemp in the back garden or a field, the costs of harvesting and processing the material can be high. However, if there is plenty of free labour it can be done using a strimmer or hand-held cutting tool but this is only appropriate for small quantities. Harvesting and processing hemp requires substantial investment as the hemp fibre is very tough and is not easy to chop up. As the materials become more widely used there should be more hemp grown and perhaps the establishment of hemp-processing plants on a regional basis that will further bring down costs.

Manufacture of a lime binder will also require investment in time and resources but competition to supply materials may increase as the technology becomes popular.

If you are determined to grow your own hemp and use some local source of lime that has not been manufactured for hemp lime building then great care must be taken to ensure that the mix and curing conditions are correct. Walls that are too damp and constructed in frosty conditions can lead to serious problems. Using the wrong lime may lead to its failing to mix properly and failing to cure. It is a serious mistake to assume that any hemp and any lime mixed together will produce good results. Hemp lime is a simple but hightechnology product that requires high standards of quality control; if carried out correctly hemp lime construction may prove to be one of the most sustainable and successful building methods ever invented.

* It is illegalto grow hemp without a licence.

2.9 ACCEPTANCE ANDACCREDITATION OFHEMP Hemp lime offers the possibility to use and protect timber frame construction with a simple build-up that creates solid walls. There is lingering concern 'in the masonry-dominated building industry about timber frame, but solid wall construction is also regarded as suspect. Some approval bodies will not currently agree to any form of construction that does not include a cavity in the walls. Despite this, there has been a growth of solid wall construction with fully filled cavities and walls built from solid aerated concrete blocks and perforated clay bricks using thin mortar beds. These forms of construction offer good levels of insulation and, with appropriate renders, are able to cope with rain and moisture.

While some accreditation bodies appear hostile to non-cavity construction, it has been possible to obtain structural insurance from a number of leading insurance companies for hemp lime construction.

By 2010-12, the process of obtaining accreditation

from Agrement boards and other approval bodies will be completed. Building Regulations approval has also been obtained on numerous projects without any significant difficulty.

At the time of writing, Tradical Hemcrete has been approved by the Local Authority Building Control Partner Scheme (www.labc.uk.com).

This means that projects using this method of hemp lime construction should have no difficulty obtaining building control approval. Estimates, based on testing of thermal performance and mechanical performance, have been accepted by a wide range of official bodies. A trade association, the Hemp Lime Construction Products Association (HLCPA), has been set up and will provide a source of information, education and performance standards as it becomes more established. The HLCPA is affiliated and linked to other mainstream trade and industry bodies, such as the UK Construction Products Association.

HEMP LIME CONSTRUCTION

Fig 2.7:

Lime mortar silo

There has been considerable investment in France, Belgium and the UK to develop the technology so that materials can be supplied in bulk.

Of course it will still be possible for small builders to order small amounts of the materials and construct more modest buildings. Materials should be available from builders' merchants before too long and can be ordered directly from the manufacturers in the meantime. Small-scale hand-crafted hemp lime buildings will still be a key part of the natural building sector.

Pioneering architect Ralph Carpenter, based in Suffolk, uses his own mixture of lime binder and has achieved good results with hemp lime buildings, but he takes great care and has a great deal of experience.

2 WHAT ISHEMP CONSTRUCTION? -

Self-builders may feel that they can manage to grow their own hemp and find some lime binder to produce buildings without going to mainstream suppliers*. A number of people have done this in the early experimental stages and even today some think that this will save them money. For small projects the savings in using non-proprietary hemp lime binder products is likely to be marginal and the risks of making up your own mix can be great.

Even if permission is sought to grow some hemp in the back garden or a field, the costs of harvesting and processing the material can be high. However, if there is plenty of free labour it can be done using a strimmer or hand-held cutting tool but this is only appropriate for small quantities. Harvesting and processing hemp requires substantial investment as the hemp fibre is very tough and is not easy to chop up. As the materials become more widely used there should be more hemp grown and perhaps the establishment of hemp-processing plants on a regional basis that will further bring down costs.

Manufacture of a lime binder will also require investment in time and resources but competition to supply materials may increase as the technology becomes popular.

If you are determined to grow your own hemp and use some local source of lime that has not been manufactured for hemp lime building then great care must be taken to ensure that the mix and curing conditions are correct. Walls that are too damp and constructed in frosty conditions can lead to serious problems. Using the wrong lime may lead to its failing to mix properly and failing to cure. It is a serious mistake to assume that any hemp and any lime mixed together will produce good results. Hemp lime is a simple but hightechnology product that requires high standards of quality control; if carried out correctly hemp lime construction may prove to be one of the most sustainable and successful building methods ever invented.

* It is illegalto grow hemp without a licence.

2.9 ACCEPTANCE ANDACCREDITATION OFHEMP Hemp lime offers the possibility to use and protect timber frame construction with a simple build-up that creates solid walls. There is lingering concern 'in the masonry-dominated building industry about timber frame, but solid wall construction is also regarded as suspect. Some approval bodies will not currently agree to any form of construction that does not include a cavity in the walls. Despite this, there has been a growth of solid wall construction with fully filled cavities and walls built from solid aerated concrete blocks and perforated clay bricks using thin mortar beds. These forms of construction offer good levels of insulation and, with appropriate renders, are able to cope with rain and moisture.

While some accreditation bodies appear hostile to non-cavity construction, it has been possible to obtain structural insurance from a number of leading insurance companies for hemp lime construction.

By 2010-12, the process of obtaining accreditation

from Agrement boards and other approval bodies will be completed. Building Regulations approval has also been obtained on numerous projects without any significant difficulty.

At the time of writing, Tradical Hemcrete has been approved by the Local Authority Building Control Partner Scheme (www.labc.uk.com).

This means that projects using this method of hemp lime construction should have no difficulty obtaining building control approval. Estimates, based on testing of thermal performance and mechanical performance, have been accepted by a wide range of official bodies. A trade association, the Hemp Lime Construction Products Association (HLCPA), has been set up and will provide a source of information, education and performance standards as it becomes more established. The HLCPA is affiliated and linked to other mainstream trade and industry bodies, such as the UK Construction Products Association.

3 CASE EXAMPLES OFHEMP LIME BUILDINGS

3 CASE EXAMPLES OFHEMPLIME BUILDINGS Table 1 lists examples of hemp lime buildings. It is followed by further information on each of the examples.

Table 1: Hemp lime buildings Project name

Location

Construction method

3.1

Adnams brewery warehouse Southwold, Suffolk and distribution centre

Building !}'.ee Large commercial building

3.2

Reconstruction of old timber frame foundry

Bury St Edmonds, Suffolk

Community building

Site-made hemp lime blocks in floor, cast wall infilled into old structure

3.3

Barn conversion

Rickmansworth, Hertfordshire

Barn conversion

Hemp lime infill to old oak frame

3.4

Self-build renovation of bungalow

Hillingdon, London

Single family house

External insulated render to existing house

3.5

Two-storey extension

Suffolk

Single family house

Hemp lime cast around timber frame·

3.6

Social housing

Haverhill, Suffolk

Social housing (two houses)

Imported hemp walls with hydraulic lime cast around timber frame

3.7

Lime Technology Ltd offices

Abingdon, Oxfordshire

Office and commercial

Renovation of existing steel frame structure with Tradical Hemcrete serated onto eermanent shuttering

3.8

Brakspear summerhouse

Worcester

Leisure

Timber frame and hemp lime shuttered i nfi II

3.9

Tradical exhibition stand at Ecobuild

Exhibition wall Ecobuild, EarlsCourt, London

Offsite prefabricated panels

3.10

Clay Fields social housing

Elrnswell, Suffolk

Social housing scheme

Spray-applied Tradical Hemcrete walls

3.11

House extension for traditional cottage

Kingston Lisle, Oxfordshire

House extension

Oak frame with hemp lime infill

3.12

WISE building, Centre for Alternative Technology

Machynlleth, Wales Conference and education centre

Diaphragm wall of limecrete (containing hemp) blocks and Tradical Hemcrete infill

Timber frame, hemp lime and some earth walling

3 CASE EXAMPLES OFHEMP LIME BUILDINGS

3 CASE EXAMPLES OFHEMPLIME BUILDINGS Table 1 lists examples of hemp lime buildings. It is followed by further information on each of the examples.

Table 1: Hemp lime buildings Project name

Location

Construction method

3.1

Adnams brewery warehouse Southwold, Suffolk and distribution centre

Building !}'.ee Large commercial building

3.2

Reconstruction of old timber frame foundry

Bury St Edmonds, Suffolk

Community building

Site-made hemp lime blocks in floor, cast wall infilled into old structure

3.3

Barn conversion

Rickmansworth, Hertfordshire

Barn conversion

Hemp lime infill to old oak frame

3.4

Self-build renovation of bungalow

Hillingdon, London

Single family house

External insulated render to existing house

3.5

Two-storey extension

Suffolk

Single family house

Hemp lime cast around timber frame·

3.6

Social housing

Haverhill, Suffolk

Social housing (two houses)

Imported hemp walls with hydraulic lime cast around timber frame

3.7

Lime Technology Ltd offices

Abingdon, Oxfordshire

Office and commercial

Renovation of existing steel frame structure with Tradical Hemcrete serated onto eermanent shuttering

3.8

Brakspear summerhouse

Worcester

Leisure

Timber frame and hemp lime shuttered i nfi II

3.9

Tradical exhibition stand at Ecobuild

Exhibition wall Ecobuild, EarlsCourt, London

Offsite prefabricated panels

3.10

Clay Fields social housing

Elrnswell, Suffolk

Social housing scheme

Spray-applied Tradical Hemcrete walls

3.11

House extension for traditional cottage

Kingston Lisle, Oxfordshire

House extension

Oak frame with hemp lime infill

3.12

WISE building, Centre for Alternative Technology

Machynlleth, Wales Conference and education centre

Diaphragm wall of limecrete (containing hemp) blocks and Tradical Hemcrete infill

Timber frame, hemp lime and some earth walling

5 BUILDING CONSTRUCTION TECHNIQUES -

HEMP LIME CONSTRUCTION

,!

.,

;~.:.

"'~•

. :~1I

S BUILDING CONSTRUCTION TECHNIQUES Hemp lime construction is very simple and can easily be assimilated by architects, specifiers and builders; however, it is advisable to attend a training course to understand all the different aspects of the subject. Such courses are currently run by companies such as Lime Technology Ltd in Abingdon and also occasionally by the Hemp Lime Construction Products Association. Similar courses are available in France through Construire En Chanvre. The Centre for Alternative Technology in Wales (CAT) runs occasional conferences on hemp lime and hands-on experience is included in postgraduate courses run by the CAT Graduate School of the Environment. Similar short courses are also available through the Low Impact Living Initiative in Buckinghamshire.

Fig 4.2:

Kenaf crop in Malaysia

This chapter gives more detail about the different construction techniques which use hemp and lime.

Figures 5.1 to 5.5 are hand drawn sketches provided by Ralph Carpenter of Modece Architects.

Ralph has been the pioneer of hemp lime construction in the UK, having learned about it from 'lsochanvre' in France. Without Ralph Carpenter's input this technique might not have been taken up in the UK. His sketches are based on various projects where these details have been used in projects that he has designed.

Figures 5.6 to 5.10 show a number of plans and sections of various configurations of hemp lime construction. Different positions are indicated for the timber frame. Details will be subject to change depending on the thickness of hemp lime used and any external cladding and junctions with other materials.

All of the details included are indicative only and any hemp lime building will require detailing appropriate to each individual project.

Fig 5. 1:

Cast hemp wall with timber rainscreen

5 BUILDING CONSTRUCTION TECHNIQUES -

HEMP LIME CONSTRUCTION

,!

.,

;~.:.

"'~•

. :~1I

S BUILDING CONSTRUCTION TECHNIQUES Hemp lime construction is very simple and can easily be assimilated by architects, specifiers and builders; however, it is advisable to attend a training course to understand all the different aspects of the subject. Such courses are currently run by companies such as Lime Technology Ltd in Abingdon and also occasionally by the Hemp Lime Construction Products Association. Similar courses are available in France through Construire En Chanvre. The Centre for Alternative Technology in Wales (CAT) runs occasional conferences on hemp lime and hands-on experience is included in postgraduate courses run by the CAT Graduate School of the Environment. Similar short courses are also available through the Low Impact Living Initiative in Buckinghamshire.

Fig 4.2:

Kenaf crop in Malaysia

This chapter gives more detail about the different construction techniques which use hemp and lime.

Figures 5.1 to 5.5 are hand drawn sketches provided by Ralph Carpenter of Modece Architects.

Ralph has been the pioneer of hemp lime construction in the UK, having learned about it from 'lsochanvre' in France. Without Ralph Carpenter's input this technique might not have been taken up in the UK. His sketches are based on various projects where these details have been used in projects that he has designed.

Figures 5.6 to 5.10 show a number of plans and sections of various configurations of hemp lime construction. Different positions are indicated for the timber frame. Details will be subject to change depending on the thickness of hemp lime used and any external cladding and junctions with other materials.

All of the details included are indicative only and any hemp lime building will require detailing appropriate to each individual project.

Fig 5. 1:

Cast hemp wall with timber rainscreen

-

5 BUILDING CONSTRUCTION TECHNiQUES

HEMP LIME CONSTRUCTION

+-----~ -·...·*

_,.,._ r "_l

( ~v

ul~1-

~ulL-

. Mf ~ g'w.NtfU\lv\_V tJtM.A. ~8)

___,'---1--1-1----l'r---"1----1----

s~I.A.,~ NE. ~J

Fig 5.2:

(L.,,_'t£c

~~

,!1"12-0~/W,'--)

Warm roof eaves with hemp lime cast around sloping rafters

'

0

'

'

..

T

Fig 5.4:

Brick plinth to timber frame wall (with hemp-based slab)

Fig 5.5:

Hemp lime slab with joists and boarded floor

,b,

·'D.·DO

'c=J .CJ

QOO.j, '

Fig 5.3:

~

Solid wall with hemp lime wall cast onto inner face

-

5 BUILDING CONSTRUCTION TECHNiQUES

HEMP LIME CONSTRUCTION

+-----~ -·...·*

_,.,._ r "_l

( ~v

ul~1-

~ulL-

. Mf ~ g'w.NtfU\lv\_V tJtM.A. ~8)

___,'---1--1-1----l'r---"1----1----

s~I.A.,~ NE. ~J

Fig 5.2:

(L.,,_'t£c

~~

,!1"12-0~/W,'--)

Warm roof eaves with hemp lime cast around sloping rafters

'

0

'

'

..

T

Fig 5.4:

Brick plinth to timber frame wall (with hemp-based slab)

Fig 5.5:

Hemp lime slab with joists and boarded floor

,b,

·'D.·DO

'c=J .CJ

QOO.j, '

Fig 5.3:

~

Solid wall with hemp lime wall cast onto inner face

5 bUILOING CONSTRUCTION TECHNIQUES

HEMP LIME CONSTRUCTION

Hemcrete<P>

Hemcrete® Stainless steel wire bead in base coat (or rounded corner) NOTE: Structural timber frame to be designed by supplier's structural engineer, including reference to adaptions needed for this detail eg bracing

Timber frame to manufacturer's design

Limetec® plaster (optional)

Structural timber frame to be designed by supplier's-,-=-~ structural engineer, 1-___k'.3.:....__,_+-~'-_:-..:..._1~C::::::_J~-,1--including reference to adaptions needed for this detail eg bracing

...

~+-----

Tradical® Hemcrete® cast or sprayed application

Proprietary expanding tape in window to board junction Projecting subcill Window board

APU bead or similar Window board Heraklith board, or similar external quality board (end grain protection as applicable).

Heraklith board thickness to suit opening width

Temporary propping required during casting or spraying Stainless steel wire bead

Timber frame to manufacturer's design

Tradical®Hemcrete® cast or sprayed application

Window position to designer's specification

Window position to designer's specification

Proprietary expanding tape in window to board junction

Stainless steel wire bead in base coat (or rounded corner)

Limetec® render (two coats)

Limetec® plaster (optional)

Limetec® render (two coats) ~'--,-!+-----

Permanent shuttering on inside face (Heraklith, Sasmox or Fermacell, or similar vapour permeable material)

NOTE:

Heraklith board, or similar external quality board (end grain protection as applicable).

Heraklith board thickness to suit opening width

-Projecting subcill APU bead or similar Temporary propping required during casting or spraying Stainless steel wire bead

Depth of Hemcrete® typically 300-500 mm Depth of Hemcrete® typically 300-500 mm

Internal

Internal

External

Fig 5.6: Plan of corner and window jamb with permanent internal shuttering board and timber frame, for spray application of hemp lime

Fig 5.7:

External

Plan of corner and window jamb with hemp lime cast between temporary shuttering boards, timber frame

in centre, with rendered outer face

5 bUILOING CONSTRUCTION TECHNIQUES

HEMP LIME CONSTRUCTION

Hemcrete<P>

Hemcrete® Stainless steel wire bead in base coat (or rounded corner) NOTE: Structural timber frame to be designed by supplier's structural engineer, including reference to adaptions needed for this detail eg bracing

Timber frame to manufacturer's design

Limetec® plaster (optional)

Structural timber frame to be designed by supplier's-,-=-~ structural engineer, 1-___k'.3.:....__,_+-~'-_:-..:..._1~C::::::_J~-,1--including reference to adaptions needed for this detail eg bracing

...

~+-----

Tradical® Hemcrete® cast or sprayed application

Proprietary expanding tape in window to board junction Projecting subcill Window board

APU bead or similar Window board Heraklith board, or similar external quality board (end grain protection as applicable).

Heraklith board thickness to suit opening width

Temporary propping required during casting or spraying Stainless steel wire bead

Timber frame to manufacturer's design

Tradical®Hemcrete® cast or sprayed application

Window position to designer's specification

Window position to designer's specification

Proprietary expanding tape in window to board junction

Stainless steel wire bead in base coat (or rounded corner)

Limetec® render (two coats)

Limetec® plaster (optional)

Limetec® render (two coats) ~'--,-!+-----

Permanent shuttering on inside face (Heraklith, Sasmox or Fermacell, or similar vapour permeable material)

NOTE:

Heraklith board, or similar external quality board (end grain protection as applicable).

Heraklith board thickness to suit opening width

-Projecting subcill APU bead or similar Temporary propping required during casting or spraying Stainless steel wire bead

Depth of Hemcrete® typically 300-500 mm Depth of Hemcrete® typically 300-500 mm

Internal

Internal

External

Fig 5.6: Plan of corner and window jamb with permanent internal shuttering board and timber frame, for spray application of hemp lime

Fig 5.7:

External

Plan of corner and window jamb with hemp lime cast between temporary shuttering boards, timber frame

in centre, with rendered outer face

5 BUILDING CONSTRUCTION TECHNIQUES

HEMP LIME CONSTRIJC1l0N

NOTE: Structural timber frame to be designed by supplier's structural engineer, including reference to adaptions needed for this detail eg bracing

NOTE: Structural timber frame to be designed by supplier's structural engineer, including reference to adaptions needed for this detail eg bracing

Counter battens Tradical®Hemcrete® cast or sprayed -----++-~ application

Breathable membrane Sarking insulation

Indicative warm roof to designers specification

Heraklith board thickness to suit opening width Heraklith board box (three or four sided)

Tiling/slating lap to architect's details

Stainless steel wire angle bead Window to architect's detail Window position to designer's specification

Temporary propping required during casting or spraying

Eaves, soffit and fascia detailing to designer's specification

Subcill fixed onto Heraklith board with bedding compound and sealing - strip Ceiling board and wet plaster finish

Timber subcill shown (alternative subject to detailing) Proprietary expanding tape in ----+-+--~ window to board junction Limetec® render (two coats) ___ Depth of Hemcrete® typically 300-500 mm

Thermal block (to reduce thermal bridging)

Window board

Closing nagging or board

Timber frame to manufacturer's design

Scrim cloth or mesh Timber frame to manufacturer's design

___.

Limetec® plaster (optional) Exposed rafters to be kept clean during works - if exposed detail specified

-------+-+--~

-------l-+--.,..;...,..,

Floor finishes

dimension subject to_~-'----site exposure-

Insulation

Good perimeter drainage Subfloor

~===~~~;;.. ______

Limetec® plaster (optional)

150 mm min

Screed

~:~~~~rrrITTrn~ Detail to be adjusted to suit footing and subfloor design

Tradical®Hemcrete® typical depth 300-500 mm cast or sprayed application

;__·Breather membrane

V/\

v'------

Permanent shuttering on inside face (Heraklith, Sasmox or Fermacell, or similar vapour permeable material)

(eg Slitex) Radon barrier/dpm h---"---"--"--"--

Fig 5.8:

as applicable (not shown)

Section with timber frame on an internal face and hemp lime sprayed or cast

Fig 5.9:

Head of wall with sloping ceiling (Warm Roof) with timber frame on inner face with permanent shuttering

5 BUILDING CONSTRUCTION TECHNIQUES

HEMP LIME CONSTRIJC1l0N

NOTE: Structural timber frame to be designed by supplier's structural engineer, including reference to adaptions needed for this detail eg bracing

NOTE: Structural timber frame to be designed by supplier's structural engineer, including reference to adaptions needed for this detail eg bracing

Counter battens Tradical®Hemcrete® cast or sprayed -----++-~ application

Breathable membrane Sarking insulation

Indicative warm roof to designers specification

Heraklith board thickness to suit opening width Heraklith board box (three or four sided)

Tiling/slating lap to architect's details

Stainless steel wire angle bead Window to architect's detail Window position to designer's specification

Temporary propping required during casting or spraying

Eaves, soffit and fascia detailing to designer's specification

Subcill fixed onto Heraklith board with bedding compound and sealing - strip Ceiling board and wet plaster finish

Timber subcill shown (alternative subject to detailing) Proprietary expanding tape in ----+-+--~ window to board junction Limetec® render (two coats) ___ Depth of Hemcrete® typically 300-500 mm

Thermal block (to reduce thermal bridging)

Window board

Closing nagging or board

Timber frame to manufacturer's design

Scrim cloth or mesh Timber frame to manufacturer's design

___.

Limetec® plaster (optional) Exposed rafters to be kept clean during works - if exposed detail specified

-------+-+--~

-------l-+--.,..;...,..,

Floor finishes

dimension subject to_~-'----site exposure-

Insulation

Good perimeter drainage Subfloor

~===~~~;;.. ______

Limetec® plaster (optional)

150 mm min

Screed

~:~~~~rrrITTrn~ Detail to be adjusted to suit footing and subfloor design

Tradical®Hemcrete® typical depth 300-500 mm cast or sprayed application

;__·Breather membrane

V/\

v'------

Permanent shuttering on inside face (Heraklith, Sasmox or Fermacell, or similar vapour permeable material)

(eg Slitex) Radon barrier/dpm h---"---"--"--"--

Fig 5.8:

as applicable (not shown)

Section with timber frame on an internal face and hemp lime sprayed or cast

Fig 5.9:

Head of wall with sloping ceiling (Warm Roof) with timber frame on inner face with permanent shuttering

5 BUILDING CONSTRUCTION TECHNIQUES -

HEMP LIME CONSTRUCTION

5.1 TIMBER FRAME CONSTRUCTION FORWALLS

NOTE:

Structural timber frame to be designed by supplier's structural engineer, including reference to adaptions needed for this detail eg bracing Tanalised vertical counter batten Tradical®Hemcrete® cast or sprayed application

Breather membrane eg Solitex plus/Tyvek Supra, or similar Timber frame to manufacturer's design Tanalised horizontal battens or rail

Ten:iporarypropping required dunng casting or spraying Heraklith board thickness to suit opening width Heraklith board box (three or four sided)

Carefully detailed weather trims to specifier's details._

Timber subcill shown (alternative subject to detailing)

Window to architect's detail Window position to designer's specification

Propri_etaryexpanding tape in window to board junction Vertical timber board cladding (approx 19 mm thick), or other proprietary rainscreen product* Vented air gap behind rainscreen

~---'-++------

Depth of Hemcrete® typically 300-500 mm Thermal block (to reduce thermal bridging)

Insect mesh wrapped around timber board and batten at the bottom end

~~~~~rn-v-vrrrr"m~

Floor finishes Screed Insulation

Good perimeter drainage Detail to be adjusted to suit footing and subfloor design

Subfloor

::====:cdt'"":"'"~------..;_-· h-~--"----"----"-

* Alternative: horizontal timber weather boarding fixed directly to breather membrane (stud face) or with vertical counter batten subject to exposure.

Fig 5.10:

Section through wall with timber frame outer face and rainscreen

Breather membrane ,, (eg Slitex) Radon barrier/dpm as applicable (not shown)

Hemp lime construction, in its most common form, is used in conjunction with timber frame. It can be used with all forms of timber frame construction 'including post and beam, stud construction, double stud and so on. Prefabricated insulated panels can also be made with hemp lime; these panels can be incorporated into various forms of construction.

Most timber frame construction in the UK is known as open panel. Timber studs are fixed together by a variety of nailing techniques into panels that are usually one storey in height. They are either prefabricated and delivered to site, or can be put together by a competent joiner onsite.

Sheathing boards are normally stapled to the frame with a breather membrane and then insulation is placed between the studs. An external cladding will be used and an internal finishing board, such as plasterboard, fixed and plastered. Such timber panels are sometimes used in multi-storey buildings and timber frame buildings of this kind can be used for both two-storey and multi-storey buildings.

If a greater depth of insulation is required then a further stud is added, known as doublestud construction. Sometimes composite timber I-beams are used to give greater depth to walls but these are expensive and usually are only used in roofs and floors. Hemp lime can be cast around a conventional open frame to give a solid wall which provides breathability, insulation, solid wall, air tightness and finishes, all in one process.

Hemp lime can be cast against a sheathing board that serves as permanent shuttering. A breather membrane and external facing materials are not required. However, brick or timber cladding can be added, if preferred, as a finish.

If hemp lime is to be used with permanent shuttering, then care must be taken in the selection of the sheeting board, which should be a breathable, vapour permeable material. This means that the normal oriented strand board (OSB) used by most timber frame companies may not be suitable. To date, most hemp lime buildings have used a proprietary board made of wood wool and magnesite, called Heraklith.

However, it is possible to use other sheathing

boards providing they are not damaged by the moisture in the wet hemp lime mix.

On other projects a proprietary product called Sasmox has been used. This is a board made from recycled gypsum and wood fibre similar to another proprietary product called Fermacell which is made from recycled gypsum and waste paper. All of these products have good environmental ratings and are also vapour permeable. Some tests have been carried out on these materials to investigate the impact of the wet hemp lime on the structural integrity and ability to dry out.

It is important to ensure that these boards are sufficiently supported by the timber frame to cope with the weight of the sprayed hemp and lime material. Further tests are likely to be done by these companies, and on other board products, as hemp lime becomes more widespread.

Open panel timber frames can be fabricated onsite. In the Haverhill Housing Association scheme (see p.22) the timber frame for the hemp lime houses was erected without internal sheathing boards. If this is done, then some kind of bracing within the timber frame may be required but it is important to consult a structural engineer about this.

While the hemp lime solid wall will provide some racking strength to lhe timber frame, further research work needs to be done before this can be relied upon in timber frame construction.

Other forms of timber frame can be used such as post and beam construction where posts are some 3 or 4 m apart. A lightweight intermediate timber sub-frame may then be required around which the hemp lime can be cast between the posts. An example of post and beam can be seen in the Croxley Green barn case study (see p.22).

The timber sub-frame is required as a framework to which shuttering can be attached.

Hemp lime solid walling in conjunction with timber frame can be seen as a versatile solution to building, providing many options for the creative and innovative designer. Walls can be curved and the material can even be sprayed onto organic shapes. There is almost no limit to the forms that can be generated providing that the essential principle is followed that the structural load is being taken by the timber frame. The hemp lime provides thermal mass, weather protection and insulation for the wall.

5 BUILDING CONSTRUCTION TECHNIQUES -

HEMP LIME CONSTRUCTION

5.1 TIMBER FRAME CONSTRUCTION FORWALLS

NOTE:

Structural timber frame to be designed by supplier's structural engineer, including reference to adaptions needed for this detail eg bracing Tanalised vertical counter batten Tradical®Hemcrete® cast or sprayed application

Breather membrane eg Solitex plus/Tyvek Supra, or similar Timber frame to manufacturer's design Tanalised horizontal battens or rail

Ten:iporarypropping required dunng casting or spraying Heraklith board thickness to suit opening width Heraklith board box (three or four sided)

Carefully detailed weather trims to specifier's details._

Timber subcill shown (alternative subject to detailing)

Window to architect's detail Window position to designer's specification

Propri_etaryexpanding tape in window to board junction Vertical timber board cladding (approx 19 mm thick), or other proprietary rainscreen product* Vented air gap behind rainscreen

~---'-++------

Depth of Hemcrete® typically 300-500 mm Thermal block (to reduce thermal bridging)

Insect mesh wrapped around timber board and batten at the bottom end

~~~~~rn-v-vrrrr"m~

Floor finishes Screed Insulation

Good perimeter drainage Detail to be adjusted to suit footing and subfloor design

Subfloor

::====:cdt'"":"'"~------..;_-· h-~--"----"----"-

* Alternative: horizontal timber weather boarding fixed directly to breather membrane (stud face) or with vertical counter batten subject to exposure.

Fig 5.10:

Section through wall with timber frame outer face and rainscreen

Breather membrane ,, (eg Slitex) Radon barrier/dpm as applicable (not shown)

Hemp lime construction, in its most common form, is used in conjunction with timber frame. It can be used with all forms of timber frame construction 'including post and beam, stud construction, double stud and so on. Prefabricated insulated panels can also be made with hemp lime; these panels can be incorporated into various forms of construction.

Most timber frame construction in the UK is known as open panel. Timber studs are fixed together by a variety of nailing techniques into panels that are usually one storey in height. They are either prefabricated and delivered to site, or can be put together by a competent joiner onsite.

Sheathing boards are normally stapled to the frame with a breather membrane and then insulation is placed between the studs. An external cladding will be used and an internal finishing board, such as plasterboard, fixed and plastered. Such timber panels are sometimes used in multi-storey buildings and timber frame buildings of this kind can be used for both two-storey and multi-storey buildings.

If a greater depth of insulation is required then a further stud is added, known as doublestud construction. Sometimes composite timber I-beams are used to give greater depth to walls but these are expensive and usually are only used in roofs and floors. Hemp lime can be cast around a conventional open frame to give a solid wall which provides breathability, insulation, solid wall, air tightness and finishes, all in one process.

Hemp lime can be cast against a sheathing board that serves as permanent shuttering. A breather membrane and external facing materials are not required. However, brick or timber cladding can be added, if preferred, as a finish.

If hemp lime is to be used with permanent shuttering, then care must be taken in the selection of the sheeting board, which should be a breathable, vapour permeable material. This means that the normal oriented strand board (OSB) used by most timber frame companies may not be suitable. To date, most hemp lime buildings have used a proprietary board made of wood wool and magnesite, called Heraklith.

However, it is possible to use other sheathing

boards providing they are not damaged by the moisture in the wet hemp lime mix.

On other projects a proprietary product called Sasmox has been used. This is a board made from recycled gypsum and wood fibre similar to another proprietary product called Fermacell which is made from recycled gypsum and waste paper. All of these products have good environmental ratings and are also vapour permeable. Some tests have been carried out on these materials to investigate the impact of the wet hemp lime on the structural integrity and ability to dry out.

It is important to ensure that these boards are sufficiently supported by the timber frame to cope with the weight of the sprayed hemp and lime material. Further tests are likely to be done by these companies, and on other board products, as hemp lime becomes more widespread.

Open panel timber frames can be fabricated onsite. In the Haverhill Housing Association scheme (see p.22) the timber frame for the hemp lime houses was erected without internal sheathing boards. If this is done, then some kind of bracing within the timber frame may be required but it is important to consult a structural engineer about this.

While the hemp lime solid wall will provide some racking strength to lhe timber frame, further research work needs to be done before this can be relied upon in timber frame construction.

Other forms of timber frame can be used such as post and beam construction where posts are some 3 or 4 m apart. A lightweight intermediate timber sub-frame may then be required around which the hemp lime can be cast between the posts. An example of post and beam can be seen in the Croxley Green barn case study (see p.22).

The timber sub-frame is required as a framework to which shuttering can be attached.

Hemp lime solid walling in conjunction with timber frame can be seen as a versatile solution to building, providing many options for the creative and innovative designer. Walls can be curved and the material can even be sprayed onto organic shapes. There is almost no limit to the forms that can be generated providing that the essential principle is followed that the structural load is being taken by the timber frame. The hemp lime provides thermal mass, weather protection and insulation for the wall.

11111

5 BUILDING CONSTRUCiTION mHNIQ~ES

HEMP WMH CONSTRUCTION

5.2 WETORDRYCONSTRUCTION?

5.5 METHODS OFPLACING HEMP ANDLIME

The construction industry is tending to move towards dry methods of building, using prefabrication and aiming for high standards of tolerances and air tightness. Spraying or placing a wet process material like hemp lime around a timber frame seems to some to be a backward step but on the other hand it is easy to do, economical and provides an exceptionally airtight method of building. The disadvantages of using wet process coqstruction must be weighed against the other advantages.

Even though prefabrication and new dry forms of timber frame construction seem very efficient, they do involve a number of trades and it is easy for things to go wrong. Great care has to be taken to ensure that the breather membrane and the air tightness barrier are properly constructed.

Even a 1 mm gap can lead to significant losses in energy efficiency, through heat loss and drafts, and moisture can get into the building fabric. In conventional timber frame construction, with so many different layers, it is easy to make mistakes by not sealing up the air gaps. However, hemp lime avoids all of these difficulties by merging several processes into one and by providing a continuous homogenous mass.

5.S.l Shuttered,cast and tamped In general, shuttered, and cast and tamped walls are suitable for self-build or smaller projects (less than 70 m 3), or where cheap or volunteer labour i5 available. In this instance temporary shuttering is fixed to the timber frame with tubular spacers to form the finished size and shape of the walls.

The hemp shiv and lime binder is mixed in a mechanical mixer approximately in the proportion of one bale of hemp shiv to two bags of binder, with approximately 60 litres of water per bale of hemp.

The lime binder bag is similar in size to the normal 25 kg cement bag.

Where proprietary materials are being supplied it is essential to follow the manufacturers' instructions.

For instance, Lime Technology Ltd recommends the following for their Tradical products: To make 1 m 3 of Tradical Hemcrete: Tradical H B content 220 kg/m3 (lime-based binder) Tradical HF content 110 kg/m3 (hemp shiv) Density of Tradical Hemcrete 330-400 kg/m 3

Fig 5.11: Modcell hemp lime panel, Ecobuild

exhibition 2007

5.3 OFFSITE CONSTRUCTION It is possible to use hemp lime with other forms of timber frame construction. For instance, insulated panels have been prefabricated offsite and erected onsite. These panels tend to be larger and heavier than conventional SIPS(structural insulated panels) but they do provide thermal mass as well as a good standard of insulation. See Figure 5.11 (Modcell: www.modcell.co.uk).

5.4 WALLDETAILS Differences in hemp lime wall construction are determined by the kind of timber frame used and the method of construction. If the hemp lime is to be sprayed onto permanent shuttering then it is necessary for the timber frame to be located at the back face of the wall for fixing the sheathing boards.

If, however, the wall is to be cast using temporary shuttering then the timber frame is usually in the centre of the wall.

The detail drawings included in chapter 5 show a number of different sections and plans depending on the position of the timber frame.

The main differences are caused by the detail used at the foot of the wall and at window and door openings. Care must be taken to ensure that there is a good tight seal around any openings.

As with any building using lime finishes and natural materials, it is advisable to provide a good overhang to the roof to reduce the amount of driving rain which is falling down the surface of the wall in areas where heavy precipitation is a problem. However, many hemp lime buildings have been constructed with conventional roof overhangs and soffits and there has been no damage to the walls.

However, the density increasesas the material dries out owing to carbonation of the lime, according to Dr Arnaud Evrard (Universite catholique de Louvain, Architecture et Climat). Once water has been added and the composite is thoroughly mixed, the material is tipped into the shuttering and lightly tamped into place. After 24 hours the shuttering can be removed, although it can be removed much earlier and raised for the next lift. It is essential not to tamp the material too firmly as this may compress the mix too much.

The density of the mix can be varied by reducing or increasing the amount of lime binder, so it is important when designing and specifying hemp lime to ensure that the correct mix is used - this mix is not always 2 to 1 as suggestedabove. The proportions of material must be carefully measured and weighed to ensure consistency throughout the wall.

Placing the material by hand in temporary shuttering may seem a slow and labour-intensive process but with careful site management it can be reasonably quick and efficient. It is also an attractive proposition for self-builders who can easily learn the technique. Hemp walls can be cast in stagesand there is no necessity to cast a whole wall in one lift.

The man-hours that went into the construction of the

Haverhill hemp houses can be found in BREReport on that project (BRE,2006), as all work was carefully monitored, but detailed figures are not available on how long it takes to cast a hemp wall. BREfound at Haverhill that the builders were able to construct the second hemp house in half the time once they had learned the technique. The time taken was therefore comparable to that for conventional construction.

Most contractors will develop ingenious ways to move the mixed material from the mixer to the shuttering.

If non-proprietary materials are being used to cast hemp walls it is essential that great care is taken to maintain consistency in the mix and that the lime binders are fit for purpose. This should only be attempted by those with a great deal of experience of working with lime (and hemp) or under the supervision of an architect who is experienced in these materials. Using pre-prepared proprietary products to the manufacturers' instructions is the best way to ensure predictable results.

5.5.2 Spray-appliedhemp lime In general, spray-applied hemp lime is suitable for larger projects (over 70 m3 ) where fast-track construction is required. The hemp lime should be mixed in the proportions recommended by the manufacturers and the water is added close to the nozzle of the spray system. This material is then sprayed against temporary or permanent, single-sided shuttering and flattened to the required surface finish (Fig. 5.12). After 24 hours temporary shuttering can be removed, but spraying is normally done with an inner skin of permanent shuttering - this can make construction quicker and simpler.

Some members of the Sprayed Concrete Association have been trained in the application of hemp lime.

Spraying the material ensures a consistency in application as placing by hand and over-tamping can lead to denser mixes.

5.5.3 Dryingand absenceof shrinRage Hemp lime should be allowed to dry before the application of any render or plaster. The period of drying will depend on a number of factors but, as a general guide, cast and tamped hemp lime should be allowed to dry out for 28 days under normal conditions or 7-10 days (if spray-applied) before the application of the render or plaster.

11111

5 BUILDING CONSTRUCiTION mHNIQ~ES

HEMP WMH CONSTRUCTION

5.2 WETORDRYCONSTRUCTION?

5.5 METHODS OFPLACING HEMP ANDLIME

The construction industry is tending to move towards dry methods of building, using prefabrication and aiming for high standards of tolerances and air tightness. Spraying or placing a wet process material like hemp lime around a timber frame seems to some to be a backward step but on the other hand it is easy to do, economical and provides an exceptionally airtight method of building. The disadvantages of using wet process coqstruction must be weighed against the other advantages.

Even though prefabrication and new dry forms of timber frame construction seem very efficient, they do involve a number of trades and it is easy for things to go wrong. Great care has to be taken to ensure that the breather membrane and the air tightness barrier are properly constructed.

Even a 1 mm gap can lead to significant losses in energy efficiency, through heat loss and drafts, and moisture can get into the building fabric. In conventional timber frame construction, with so many different layers, it is easy to make mistakes by not sealing up the air gaps. However, hemp lime avoids all of these difficulties by merging several processes into one and by providing a continuous homogenous mass.

5.S.l Shuttered,cast and tamped In general, shuttered, and cast and tamped walls are suitable for self-build or smaller projects (less than 70 m 3), or where cheap or volunteer labour i5 available. In this instance temporary shuttering is fixed to the timber frame with tubular spacers to form the finished size and shape of the walls.

The hemp shiv and lime binder is mixed in a mechanical mixer approximately in the proportion of one bale of hemp shiv to two bags of binder, with approximately 60 litres of water per bale of hemp.

The lime binder bag is similar in size to the normal 25 kg cement bag.

Where proprietary materials are being supplied it is essential to follow the manufacturers' instructions.

For instance, Lime Technology Ltd recommends the following for their Tradical products: To make 1 m 3 of Tradical Hemcrete: Tradical H B content 220 kg/m3 (lime-based binder) Tradical HF content 110 kg/m3 (hemp shiv) Density of Tradical Hemcrete 330-400 kg/m 3

Fig 5.11: Modcell hemp lime panel, Ecobuild

exhibition 2007

5.3 OFFSITE CONSTRUCTION It is possible to use hemp lime with other forms of timber frame construction. For instance, insulated panels have been prefabricated offsite and erected onsite. These panels tend to be larger and heavier than conventional SIPS(structural insulated panels) but they do provide thermal mass as well as a good standard of insulation. See Figure 5.11 (Modcell: www.modcell.co.uk).

5.4 WALLDETAILS Differences in hemp lime wall construction are determined by the kind of timber frame used and the method of construction. If the hemp lime is to be sprayed onto permanent shuttering then it is necessary for the timber frame to be located at the back face of the wall for fixing the sheathing boards.

If, however, the wall is to be cast using temporary shuttering then the timber frame is usually in the centre of the wall.

The detail drawings included in chapter 5 show a number of different sections and plans depending on the position of the timber frame.

The main differences are caused by the detail used at the foot of the wall and at window and door openings. Care must be taken to ensure that there is a good tight seal around any openings.

As with any building using lime finishes and natural materials, it is advisable to provide a good overhang to the roof to reduce the amount of driving rain which is falling down the surface of the wall in areas where heavy precipitation is a problem. However, many hemp lime buildings have been constructed with conventional roof overhangs and soffits and there has been no damage to the walls.

However, the density increasesas the material dries out owing to carbonation of the lime, according to Dr Arnaud Evrard (Universite catholique de Louvain, Architecture et Climat). Once water has been added and the composite is thoroughly mixed, the material is tipped into the shuttering and lightly tamped into place. After 24 hours the shuttering can be removed, although it can be removed much earlier and raised for the next lift. It is essential not to tamp the material too firmly as this may compress the mix too much.

The density of the mix can be varied by reducing or increasing the amount of lime binder, so it is important when designing and specifying hemp lime to ensure that the correct mix is used - this mix is not always 2 to 1 as suggestedabove. The proportions of material must be carefully measured and weighed to ensure consistency throughout the wall.

Placing the material by hand in temporary shuttering may seem a slow and labour-intensive process but with careful site management it can be reasonably quick and efficient. It is also an attractive proposition for self-builders who can easily learn the technique. Hemp walls can be cast in stagesand there is no necessity to cast a whole wall in one lift.

The man-hours that went into the construction of the

Haverhill hemp houses can be found in BREReport on that project (BRE,2006), as all work was carefully monitored, but detailed figures are not available on how long it takes to cast a hemp wall. BREfound at Haverhill that the builders were able to construct the second hemp house in half the time once they had learned the technique. The time taken was therefore comparable to that for conventional construction.

Most contractors will develop ingenious ways to move the mixed material from the mixer to the shuttering.

If non-proprietary materials are being used to cast hemp walls it is essential that great care is taken to maintain consistency in the mix and that the lime binders are fit for purpose. This should only be attempted by those with a great deal of experience of working with lime (and hemp) or under the supervision of an architect who is experienced in these materials. Using pre-prepared proprietary products to the manufacturers' instructions is the best way to ensure predictable results.

5.5.2 Spray-appliedhemp lime In general, spray-applied hemp lime is suitable for larger projects (over 70 m3 ) where fast-track construction is required. The hemp lime should be mixed in the proportions recommended by the manufacturers and the water is added close to the nozzle of the spray system. This material is then sprayed against temporary or permanent, single-sided shuttering and flattened to the required surface finish (Fig. 5.12). After 24 hours temporary shuttering can be removed, but spraying is normally done with an inner skin of permanent shuttering - this can make construction quicker and simpler.

Some members of the Sprayed Concrete Association have been trained in the application of hemp lime.

Spraying the material ensures a consistency in application as placing by hand and over-tamping can lead to denser mixes.

5.5.3 Dryingand absenceof shrinRage Hemp lime should be allowed to dry before the application of any render or plaster. The period of drying will depend on a number of factors but, as a general guide, cast and tamped hemp lime should be allowed to dry out for 28 days under normal conditions or 7-10 days (if spray-applied) before the application of the render or plaster.

5 BUILDING CONSTRUCTION TECHNIQUES

HEMP LIME CONSTRUCTION

It should be recognised that the hygroscopic nature of hemp lime means that it will rarely be absolutely dry. The rate of drying will be influenced by the nature of the lime-based binder, the amount of water added at construction, and the ambient conditions experienced during the curing period. Manufacturers should be able to provide further information. The hygroscopic nature of the material should not be seen as a problem but as an advantage, as the material is able to absorb moisture and then give it off again.

The ability of natural materials to handle moisture contributes to a healthier indoor environment as problems of humidity and condensation are much reduced.

As the material dries out it is unlikely that there will be any shrinkage, cracking or similar problems if the wall has been properly constructed. Lime is much more flexible than cement and we have yet to come across any problems of this nature with hemp lime. Of course cracks may be caused by other movement in other structural components in the building, but the hemp lime is relatively flexible.

ROOF CONSTRUCTION

5.6 BLOCK CONSTRUCTION

5.7

When first introduced to the idea of hemp lime construction many people assume that it will be used to make lightweight concrete-type blocks. This can be done and in some situations it is the most appropriate way to use the material. However, it is much more cost effective to cast and tamp or spray the material to provide a continuous form of walling.

A range of blocks has been made with hemp lime and at different densities. With a higher proportion of lime binder and with some sand added, denser and stronger blocks can be created. It is possible to achieve a crushing strength at the lower end of the scale for Portland cement concrete blocks.

These do not provide a very good level of insulation, however, as they are very dense. Lighter weight blocks can also be made. In the Adnams brewery project (see p.20), chalk, lime and hemp blocks were made using material from on the site and these were formed into diaphragm walls (Fig. 5.13).

Blocks can be used as infill and they have also been used as freestanding walls, well protected with a substantial coping.

In France it has been quite common to construct timber roofs with solid hemp lime insulation. This is usually done by lining the underside of the roof rafters with a strong permanent shuttering board which then acts as the ceiling lining (Fig. 5.14).

Hemp lime is then sprayed on top and levelled off with the top of the rafters. A breather membrane and counter battening is then fixed above with a normal roof finish. The hemp lime mix is much less dense than that used in walls, having a lower proportion of lime binder. This form of construction has not yet been used to any great extent in the UK and care should be taken, with professional advice sought before it is used. We are not yet in a position to advise on the correct mix for this until more scientific testing has been done but Lhoist Ltd suggests 1 : 1 Tradical HB to Tradical HF (binder to hemp). This use of the material should therefore still be regarded as experimental.

We have also come across examples of hemp lime being cast on top of flat ceilings. We think that there are other more appropriate lightweight insulation materials to be used in this context.

5.8 FOOTINGS ANDGROUND FLOOR SLABS Limecrete has been used for foundations and footings successfully, usually where loads are lighter such as in timber frame buildings. Limecrete is similar to concrete where hydraulic lime is substituted for cement. This may be done for environmental reasons or because the foundations need to be more flexible. Hydraulic lime can also be waterproof and can cope very well in wet ground conditions. However, there is no particular need to use limecrete with a hemp lime building unless this is a material of choice.

Hemp lime walls can be constructed onto almost any kind of ground floor construction, conventional concrete strip footings, prefabricated piled footings, reinforced slabs or a post and beam timber frame where the wall is infilled on top of timber beams. A few examples are shown in the section drawings shown earlier in this chapter. It is normal practice to use a damp-proof course as in conventional building construction.

Hemp lime can be cast as an insulating floor screed, either on top of a conventional concrete slab or in place of it. Ralph Carpenter has cast a slab directly onto compacted hardcore in his own house in Suffolk, without a damp-proof membrane. After a number of years this has shown no sign of damp.

However, it is perfectly simple to cast a hemp lime screed or slab on top of a conventional damp-proof membrane and this may be necessary if it is also serving as a radon barrier.

Hemp lime floors can be finished with ceramic tiles bedded in a lime mortar. It is also possible to have a floating floor, timber battens and timber boards or timber composite products laid on top.

If a hemp lime floor is to be cast directly on top of hardcore this may not meet approval under the Building Regulations, as a damp-proof membrane may be required.

It is important that whatever form of floor construction is used that moisture should be able to escape.

Fig 5.12:

Spraying in progress

Diaphragm wall of chalk, lime and hemp blocks at Adnams brewery under construction

Fig 5.13:

Fig 5. 14: Hemp lime insulation cast between rafters

5 BUILDING CONSTRUCTION TECHNIQUES

HEMP LIME CONSTRUCTION

It should be recognised that the hygroscopic nature of hemp lime means that it will rarely be absolutely dry. The rate of drying will be influenced by the nature of the lime-based binder, the amount of water added at construction, and the ambient conditions experienced during the curing period. Manufacturers should be able to provide further information. The hygroscopic nature of the material should not be seen as a problem but as an advantage, as the material is able to absorb moisture and then give it off again.

The ability of natural materials to handle moisture contributes to a healthier indoor environment as problems of humidity and condensation are much reduced.

As the material dries out it is unlikely that there will be any shrinkage, cracking or similar problems if the wall has been properly constructed. Lime is much more flexible than cement and we have yet to come across any problems of this nature with hemp lime. Of course cracks may be caused by other movement in other structural components in the building, but the hemp lime is relatively flexible.

ROOF CONSTRUCTION

5.6 BLOCK CONSTRUCTION

5.7

When first introduced to the idea of hemp lime construction many people assume that it will be used to make lightweight concrete-type blocks. This can be done and in some situations it is the most appropriate way to use the material. However, it is much more cost effective to cast and tamp or spray the material to provide a continuous form of walling.

A range of blocks has been made with hemp lime and at different densities. With a higher proportion of lime binder and with some sand added, denser and stronger blocks can be created. It is possible to achieve a crushing strength at the lower end of the scale for Portland cement concrete blocks.

These do not provide a very good level of insulation, however, as they are very dense. Lighter weight blocks can also be made. In the Adnams brewery project (see p.20), chalk, lime and hemp blocks were made using material from on the site and these were formed into diaphragm walls (Fig. 5.13).

Blocks can be used as infill and they have also been used as freestanding walls, well protected with a substantial coping.

In France it has been quite common to construct timber roofs with solid hemp lime insulation. This is usually done by lining the underside of the roof rafters with a strong permanent shuttering board which then acts as the ceiling lining (Fig. 5.14).

Hemp lime is then sprayed on top and levelled off with the top of the rafters. A breather membrane and counter battening is then fixed above with a normal roof finish. The hemp lime mix is much less dense than that used in walls, having a lower proportion of lime binder. This form of construction has not yet been used to any great extent in the UK and care should be taken, with professional advice sought before it is used. We are not yet in a position to advise on the correct mix for this until more scientific testing has been done but Lhoist Ltd suggests 1 : 1 Tradical HB to Tradical HF (binder to hemp). This use of the material should therefore still be regarded as experimental.

We have also come across examples of hemp lime being cast on top of flat ceilings. We think that there are other more appropriate lightweight insulation materials to be used in this context.

5.8 FOOTINGS ANDGROUND FLOOR SLABS Limecrete has been used for foundations and footings successfully, usually where loads are lighter such as in timber frame buildings. Limecrete is similar to concrete where hydraulic lime is substituted for cement. This may be done for environmental reasons or because the foundations need to be more flexible. Hydraulic lime can also be waterproof and can cope very well in wet ground conditions. However, there is no particular need to use limecrete with a hemp lime building unless this is a material of choice.

Hemp lime walls can be constructed onto almost any kind of ground floor construction, conventional concrete strip footings, prefabricated piled footings, reinforced slabs or a post and beam timber frame where the wall is infilled on top of timber beams. A few examples are shown in the section drawings shown earlier in this chapter. It is normal practice to use a damp-proof course as in conventional building construction.

Hemp lime can be cast as an insulating floor screed, either on top of a conventional concrete slab or in place of it. Ralph Carpenter has cast a slab directly onto compacted hardcore in his own house in Suffolk, without a damp-proof membrane. After a number of years this has shown no sign of damp.

However, it is perfectly simple to cast a hemp lime screed or slab on top of a conventional damp-proof membrane and this may be necessary if it is also serving as a radon barrier.

Hemp lime floors can be finished with ceramic tiles bedded in a lime mortar. It is also possible to have a floating floor, timber battens and timber boards or timber composite products laid on top.

If a hemp lime floor is to be cast directly on top of hardcore this may not meet approval under the Building Regulations, as a damp-proof membrane may be required.

It is important that whatever form of floor construction is used that moisture should be able to escape.

Fig 5.12:

Spraying in progress

Diaphragm wall of chalk, lime and hemp blocks at Adnams brewery under construction

Fig 5.13:

Fig 5. 14: Hemp lime insulation cast between rafters

5 BUILDING CONSTRUCTION TECHNIQUES

5.12 RENOVATION ANDUSEIN HISTORIC

BUILDINGS It is possible to use hemp lime mixes in building renovation as effectively as in new construction. The basic principles apply as for new build but with a few differences (Fig. 5.16). s.12.1 Infill to timber frame Hemp lime can be cast, using the same mixes and methods as in new build, into timber frame structures in old buildings or new buildings that use green oak or similar. This can be done by

Fig 5. 15: Hemp lime floor being cast

5.9 SURFACE FINISHES

s.10 MEMBRANES

Hemp lime walls need to be kept dry during construction. It is advisable to arrange temporary protection against driving rain while the material is drying out and curing.

It is best to finish the walls with an external surface that is vapour permeable. Since hemp lime is a breathable material, and this is one of its main advantages, it would not make sense to cover it with an impermeable material. Ideally the finish should be a lime render, which is either lime washed or self-coloured. Other finishes can include timber rainscreen that can be fixed directly onto the hemp lime wall or with an air gap. Tile or shingle hanging and stonework and brickwork can also be used if set in a lime mortar.

Any paint finishes should be vapour permeable.

Polymer-based paints and renders should not be used. Silicate mineral paints can be used.

Internally, clay paint, soft distemper lime wash and water-based emulsions can be used. It is best to use natural paints that are low in volatile organic compounds so as not to compromise the health benefits of using hemp lime.

Hemp lime provides a fully breathing wall system. It is important not to use impermeable membranes in contact with the walls such as plastic sheeting or foil-backed boards; however, breathing membranes such as those used against timber cladding may be used as separation layers. A damp proof course should be used at the base of the walls (slate being the natural material). There may also be a conflicting need for an impermeable barrier (eg for radon-proof measures).

s.11 FIXINGS It is possible to fix into hemp lime walls with a range of proprietary fixings. Heavy items should be fixed back to the timber frame. It is best to design the building and the timber frame so that, in circumstances where wall cupboards and other elements need to be fixed to the wall, the timber frame is on the surface of the wall to facilitate this.

Fig 5.16: Hemp and lime infill in an historic building

making the hemp lime into bricks or blocks, or simply casting as one solid mass. The method was developed for historic building conservation initially. Hemp lime is ideally suited to use with timber frame as it mimics the old wattle and daub infills and the lime protects the timber as it has done for centuries. The hemp lime composite is very flexible and can cope with some movement in timber. The flexibility and the lack of cracking can ensure that the walls remain airtight. Infill can be of very small sections or whole walls.

5 BUILDING CONSTRUCTION TECHNIQUES

5.12 RENOVATION ANDUSEIN HISTORIC

BUILDINGS It is possible to use hemp lime mixes in building renovation as effectively as in new construction. The basic principles apply as for new build but with a few differences (Fig. 5.16). s.12.1 Infill to timber frame Hemp lime can be cast, using the same mixes and methods as in new build, into timber frame structures in old buildings or new buildings that use green oak or similar. This can be done by

Fig 5. 15: Hemp lime floor being cast

5.9 SURFACE FINISHES

s.10 MEMBRANES

Hemp lime walls need to be kept dry during construction. It is advisable to arrange temporary protection against driving rain while the material is drying out and curing.

It is best to finish the walls with an external surface that is vapour permeable. Since hemp lime is a breathable material, and this is one of its main advantages, it would not make sense to cover it with an impermeable material. Ideally the finish should be a lime render, which is either lime washed or self-coloured. Other finishes can include timber rainscreen that can be fixed directly onto the hemp lime wall or with an air gap. Tile or shingle hanging and stonework and brickwork can also be used if set in a lime mortar.

Any paint finishes should be vapour permeable.

Polymer-based paints and renders should not be used. Silicate mineral paints can be used.

Internally, clay paint, soft distemper lime wash and water-based emulsions can be used. It is best to use natural paints that are low in volatile organic compounds so as not to compromise the health benefits of using hemp lime.

Hemp lime provides a fully breathing wall system. It is important not to use impermeable membranes in contact with the walls such as plastic sheeting or foil-backed boards; however, breathing membranes such as those used against timber cladding may be used as separation layers. A damp proof course should be used at the base of the walls (slate being the natural material). There may also be a conflicting need for an impermeable barrier (eg for radon-proof measures).

s.11 FIXINGS It is possible to fix into hemp lime walls with a range of proprietary fixings. Heavy items should be fixed back to the timber frame. It is best to design the building and the timber frame so that, in circumstances where wall cupboards and other elements need to be fixed to the wall, the timber frame is on the surface of the wall to facilitate this.

Fig 5.16: Hemp and lime infill in an historic building

making the hemp lime into bricks or blocks, or simply casting as one solid mass. The method was developed for historic building conservation initially. Hemp lime is ideally suited to use with timber frame as it mimics the old wattle and daub infills and the lime protects the timber as it has done for centuries. The hemp lime composite is very flexible and can cope with some movement in timber. The flexibility and the lack of cracking can ensure that the walls remain airtight. Infill can be of very small sections or whole walls.

5 BUILDING CONSTRUCTION TECHN;QUES -

HEMP l:IME CONSTRUCTION

s.12.2 Castingand insulating render Hemp lime can also be cast directly against old stone, brick or cob (earth) walls, either inside or outside (Fig. 5.17). This can be done with shuttering, which is temporarily fixed to the walls, using timber studs as in new build. The studs can be removed and the gaps filled in with hemp lime. This provides a form of insulation that is also able to cope with moderate levels of dampness in

the existing walls. It will go onto uneven surfaces without difficulty. It is necessary for the existing walls to be cleaned of dust and loose matter and any synthetic paints or other unsuitable material removed.

This method can be used internally as a direct replacement for lath and plaster where this is in poor condition and has to be removed. It is a much more effective solution to ·renovation than dry lining. This is because it ensures continuing breathability of the walls and there are no cavities for hidden condensation. Thermal mass is also retained.

On buildings where there is no attractive outside finish, such as dressed stone or brick detailing, the hemp lime material can be applied externally with a lime render finish. This works even more effectively as it insulates the existing thermal mass. Care needs to be taken to ensure a good seal around window and door openings.

At the moment there are insufficient data on the thermal effectiveness of insulating and renovating hemp lime render, but anecdotal information suggeststhat it is successful in increasing air tightness and reducing energy consumption. Buildings that have been rendered internally in this way have experienced improved energy performance. Although a hemp lime coating may not greatly improve the U-value of the wall, it will have a beneficial effect on the buffering of humidity and temperature changes as well as improving the air tightness by acting as a sealing coating and improving feelings of comfort through its diffusivity characteristics.

In a Diocesan office building in Chalons-enChampagne in France, where 65 mm of Tradical hemp lime plaster was applied to the old stone walls, significant reductions in energy bills have been claimed (Fig. 5.18).

5.13 PLASTERING WITHHEMP ANDLIME

5.14 TIMBER FRAME ANDHEMPMODEL

Thin plaster coats of hemp lime can be applied to walls both internally and externally by hand or with a spray machine (Fig. 5.19). There are buildings where it has been used as an external coat to straw bale walls and it has been used as a finish on old buildings. If a thin plaster coat is to be used then it is better to use a proprietary product such as Hemcoat that has been developed for this purpose. Advice from suppliers should be obtained about the best materials to be used for the thickness required.

In order to demonstrate the simplicity of hemp lime construction for housing we constructed a model at the Lime Technology Ltd head office in Abingdon showing how hemp lime is applied to a timber frame; this is illustrated in Figure 5.20.

In this case the walls were cast using plywood shuttering, and the hemp lime placed by hand and tamped.

Fig5. 17: Bungalow in Hil/ingdon,London, with external hemp lime render

Fig5. 19: Internal hemp lime plaster in Eardisland,Herefordshire

Fig5. 18: Stone building in Cha/ons-en-Champagne renovated with hemp lime plaster Fig5.20: Model of timber frame and hemp

5 BUILDING CONSTRUCTION TECHN;QUES -

HEMP l:IME CONSTRUCTION

s.12.2 Castingand insulating render Hemp lime can also be cast directly against old stone, brick or cob (earth) walls, either inside or outside (Fig. 5.17). This can be done with shuttering, which is temporarily fixed to the walls, using timber studs as in new build. The studs can be removed and the gaps filled in with hemp lime. This provides a form of insulation that is also able to cope with moderate levels of dampness in

the existing walls. It will go onto uneven surfaces without difficulty. It is necessary for the existing walls to be cleaned of dust and loose matter and any synthetic paints or other unsuitable material removed.

This method can be used internally as a direct replacement for lath and plaster where this is in poor condition and has to be removed. It is a much more effective solution to ·renovation than dry lining. This is because it ensures continuing breathability of the walls and there are no cavities for hidden condensation. Thermal mass is also retained.

On buildings where there is no attractive outside finish, such as dressed stone or brick detailing, the hemp lime material can be applied externally with a lime render finish. This works even more effectively as it insulates the existing thermal mass. Care needs to be taken to ensure a good seal around window and door openings.

At the moment there are insufficient data on the thermal effectiveness of insulating and renovating hemp lime render, but anecdotal information suggeststhat it is successful in increasing air tightness and reducing energy consumption. Buildings that have been rendered internally in this way have experienced improved energy performance. Although a hemp lime coating may not greatly improve the U-value of the wall, it will have a beneficial effect on the buffering of humidity and temperature changes as well as improving the air tightness by acting as a sealing coating and improving feelings of comfort through its diffusivity characteristics.

In a Diocesan office building in Chalons-enChampagne in France, where 65 mm of Tradical hemp lime plaster was applied to the old stone walls, significant reductions in energy bills have been claimed (Fig. 5.18).

5.13 PLASTERING WITHHEMP ANDLIME

5.14 TIMBER FRAME ANDHEMPMODEL

Thin plaster coats of hemp lime can be applied to walls both internally and externally by hand or with a spray machine (Fig. 5.19). There are buildings where it has been used as an external coat to straw bale walls and it has been used as a finish on old buildings. If a thin plaster coat is to be used then it is better to use a proprietary product such as Hemcoat that has been developed for this purpose. Advice from suppliers should be obtained about the best materials to be used for the thickness required.

In order to demonstrate the simplicity of hemp lime construction for housing we constructed a model at the Lime Technology Ltd head office in Abingdon showing how hemp lime is applied to a timber frame; this is illustrated in Figure 5.20.

In this case the walls were cast using plywood shuttering, and the hemp lime placed by hand and tamped.

Fig5. 17: Bungalow in Hil/ingdon,London, with external hemp lime render

Fig5. 19: Internal hemp lime plaster in Eardisland,Herefordshire

Fig5. 18: Stone building in Cha/ons-en-Champagne renovated with hemp lime plaster Fig5.20: Model of timber frame and hemp

13 REFERENCES ANDNOTES

13 REFERENCES ANDNOTES Adan O (1994). On the fungal defacement of interior

Arnaud L, Cordier C, Sallet F (2000). Mechanical and

finishes. PhD thesis. Eindhoven University of Technology,

thermal properties of vegetal concrete. Proceedings o(

Eindhoven, Netherlands.

the International Conference on Sustainable Construction

AndersonJ,Shiers D (2002). The green guide lo specification. 3rd edition. Blackwells, Oxford.

AndersonJ,EdwardsS (2000). Addendum lo BRE methodology (or environmental profiles of construction materials, components and buildings. Centre for Sustainable

Construction, BRE, Watford.

Arnaud L (2000). Mechanical and thermal properties o( hemp mortars and wools: experimental and theoretical approaches. Conference invitee, 3rd International

Symposium on Bioresource Hemp and Other Fibre Crops, Wolfsburg, USA, 13-16 September 2000.

Arnaud L, Cerezo V (2002). Mechanical, thermal and acoustical properties of concrete containing vegetable

into the Next Millennium: Environmentally Friendly and Innovative Cement-based Materials. Joao Pessoa, Brazil,

2-5 November 2000, pp. 39-44.

Arnaud L, Monnet H, Cordier C, Sallet F (2000).

Modelisation par homogeneisation autocoherente de la conductivite thennique de betons et laines de chanvre. Proc.

Congres Franc;aisde thermique, 15-17 May 2000.

Arup/Dunster B (2005). Arup R&D & Bill Dunster: heavyweight vs. lightweight construction. January 2005. Ove

Arup and Partners, London.

Ashrae Handbook (1997). Fundamentals. American Society of Heating Refrigerating, and Air-Conditioning Engineers, Inc., Atlanta.

particles. In: VM Malhorta (ed.), Proceedings of the AC/

BaggsS, BaggsJ(1996). The healthy house: the Caian

5th International

approach to creating

Conference on Innovations in Design

with Emphasis on Seismic, Wind and Environmental Loading: Quality Control and Innovations in Materials, Hot-weather

Concreting. Cancun, Mexico, December

2002, pp.151-168.

Arnaud L, Samri D (2005). Hygrothermal behaviour of

a safe healthy and environmentally

friendly home. Harper & Collins, Sydney.

HERR.www.berr.gov.uk/sectors/construction/sustainability/ page13691.html.

BLF(May 2007). Newsletter. Vol. 9, issue 2.

porous building materials. Proc. Third lnt. Biol Conference.

BowerJ (1993). Healthy house building. The Healthy House

Oklahoma City, USA, 2005.

Institute, Unionville, Indiana.

Arnaud Let al (2003). Proprietes physiques des Betons de

BRE(2002). Client report: final report on the construction of

Chanvre.

the hemp houses at Haverhill, Suffolk. Client report number

Arnaud L, Cerezo V, Boutin C (2004). Physical properties of concrete with vegetable particles. In: C Boutin, M Lefik (eds). Experimental knowledge versus theoretical models,

209-71 7, rev.1 (revised 22 October 2002). Prepared for: Steve Clarke, Suffolk Housing Society Ltd, 13 August 2002.

See www.suffolkhousing.org/pages/hempage.html

soils and composite materials. American Concrete Institute

BRE(2006). BREcertification scheme document:

Publications.

environmental profiles o( construction products. SD 028,

Arnaud L, Cerezo V, Samri D (2006). Global approach

Issue 2. BRE Certification Limited, Watford.

for the design of building material containing lime and

BRECertification (2006). Certification o( environmental

vegetable particles. Proceedings of the 6th International

profiles: life-cycle assessment of construction products.

Symposium on Cement and Concrete. Xi'An, China,

www.bre.co.uk (last consulted December 2006).

August 2006.

BREprojects.www.projects.bre.co.uk/hemphomes.

13 REFERENCES ANDNOTES

13 REFERENCES ANDNOTES Adan O (1994). On the fungal defacement of interior

Arnaud L, Cordier C, Sallet F (2000). Mechanical and

finishes. PhD thesis. Eindhoven University of Technology,

thermal properties of vegetal concrete. Proceedings o(

Eindhoven, Netherlands.

the International Conference on Sustainable Construction

AndersonJ,Shiers D (2002). The green guide lo specification. 3rd edition. Blackwells, Oxford.

AndersonJ,EdwardsS (2000). Addendum lo BRE methodology (or environmental profiles of construction materials, components and buildings. Centre for Sustainable

Construction, BRE, Watford.

Arnaud L (2000). Mechanical and thermal properties o( hemp mortars and wools: experimental and theoretical approaches. Conference invitee, 3rd International

Symposium on Bioresource Hemp and Other Fibre Crops, Wolfsburg, USA, 13-16 September 2000.

Arnaud L, Cerezo V (2002). Mechanical, thermal and acoustical properties of concrete containing vegetable

into the Next Millennium: Environmentally Friendly and Innovative Cement-based Materials. Joao Pessoa, Brazil,

2-5 November 2000, pp. 39-44.

Arnaud L, Monnet H, Cordier C, Sallet F (2000).

Modelisation par homogeneisation autocoherente de la conductivite thennique de betons et laines de chanvre. Proc.

Congres Franc;aisde thermique, 15-17 May 2000.

Arup/Dunster B (2005). Arup R&D & Bill Dunster: heavyweight vs. lightweight construction. January 2005. Ove

Arup and Partners, London.

Ashrae Handbook (1997). Fundamentals. American Society of Heating Refrigerating, and Air-Conditioning Engineers, Inc., Atlanta.

particles. In: VM Malhorta (ed.), Proceedings of the AC/

BaggsS, BaggsJ(1996). The healthy house: the Caian

5th International

approach to creating

Conference on Innovations in Design

with Emphasis on Seismic, Wind and Environmental Loading: Quality Control and Innovations in Materials, Hot-weather

Concreting. Cancun, Mexico, December

2002, pp.151-168.

Arnaud L, Samri D (2005). Hygrothermal behaviour of

a safe healthy and environmentally

friendly home. Harper & Collins, Sydney.

HERR.www.berr.gov.uk/sectors/construction/sustainability/ page13691.html.

BLF(May 2007). Newsletter. Vol. 9, issue 2.

porous building materials. Proc. Third lnt. Biol Conference.

BowerJ (1993). Healthy house building. The Healthy House

Oklahoma City, USA, 2005.

Institute, Unionville, Indiana.

Arnaud Let al (2003). Proprietes physiques des Betons de

BRE(2002). Client report: final report on the construction of

Chanvre.

the hemp houses at Haverhill, Suffolk. Client report number

Arnaud L, Cerezo V, Boutin C (2004). Physical properties of concrete with vegetable particles. In: C Boutin, M Lefik (eds). Experimental knowledge versus theoretical models,

209-71 7, rev.1 (revised 22 October 2002). Prepared for: Steve Clarke, Suffolk Housing Society Ltd, 13 August 2002.

See www.suffolkhousing.org/pages/hempage.html

soils and composite materials. American Concrete Institute

BRE(2006). BREcertification scheme document:

Publications.

environmental profiles o( construction products. SD 028,

Arnaud L, Cerezo V, Samri D (2006). Global approach

Issue 2. BRE Certification Limited, Watford.

for the design of building material containing lime and

BRECertification (2006). Certification o( environmental

vegetable particles. Proceedings of the 6th International

profiles: life-cycle assessment of construction products.

Symposium on Cement and Concrete. Xi'An, China,

www.bre.co.uk (last consulted December 2006).

August 2006.

BREprojects.www.projects.bre.co.uk/hemphomes.

13 REFERENCES ANDNOTES

HEMP LIME CONSTRUCTION Biitschi P-Y. (2004). Utilisation du chanvre pour la

Evrard A (2006). Sorption behaviour of lime-hemp

Kehrer MM, Kunzel HM, Sedlbauer K (2003). Ecological

prefabrication d'elements de construction. PhD thesis.

concrete and its relation to indoor comfort and energy

insulation materials: does sorption moisture affect their

Universite de Moncton, Canada, May 2004.

demand. PLEA2006, The 23rd Conference on Passive

insulation performance? Journal of Thermal Envelope and

and Low-energy Architecture, Geneva, Switzerland,

Building Science, 26(3).

C CaLC. A systematic approach lo estimation of life cycle carbon inventory, carbon footprints and embodied carbon.

6-8 September 2006.

Kioy Stella M (2005). Lime-hemp composites: compressive

Project website: www.surrey.ac.uk/CES/CCalC/ (last

Evrard A (2008). Transient hygrothermal behaviour of

strength and resistance to fungal attacks. MEng dissertation.

consulted November 2006).

lime-hemp materials. PhD in applied science. Universite

Department of Architecture & Civil Engineering, University

catholique de Louvain.

of Bath, May 2005.

Evrard A, De Herde A (2005). Bioclimatic envelopes made

Krusche P,Weig-Krusche M, Althaus D, Gabriel

of lime and hemp concrete. Proceedings of CISBAT2005.

Oekologisches Bauen. Bauverlag, Berlin.

Centre Scientifique et Technique du Batiment.

http://i nternational .cstb.fr.

Cerezo V (2005). Proprietes mecaniques, thermique et acoustique d'uri•materiau

abase de particules

vegetales:

approche experimentale et modelisation theorique, N°ordre:

Ecole Polytechnique Federale de Lausanne, Switzerland, September 2005. www.wufi-pro.com.

Evrard A, De Herde A, Minet J (2006). Dynamical

Lyon (Mecanique, Energetique, Genie Civil, Acoustique).

interactions between heat and mass flows in lime-hemp

acoustiques d'un materiau

abase de particules

vegetates:

approche experimentale et modelisation theorique. PhD

Kuenzel H (1980). Muessen Aussenwaende eatmungsfaehigf

sein? WKSB, November 1980, pp. 1-4.

05 /SAL. PhD thesis. Ecole doctorale and Master MEGA de

Cerezo V (2005). Proprietes mecaniques, thermiques et

I (1982).

concrete. Proceedings of the Third International Building Physics Conference. Concordia University, Canada and the

International Association of Building Physics, August 2005.

Kuenzel HM (1997). WUFI V2.0: simultaneous heat and moisture transport in building components. Fraunhofer

Institute for Building Physics, August 1997.

Lacinski P (1996). Breathing wall, the last straw. Journal of Strawbale Construction, Spring 1996.

thesis. Ecole Nationale des Travaux Publics de l'Etat, France,

Fisk W, Rosenfeld A (1997). Improved productivity and

June 2005.

health from better indoor environments. Center for Building

Levon B.-V (1986). Experimentbyggnade i Norden. Swedish

Science Newsletter. Lawrence-Berkeley Labs.

Council for Building Research, Report T5, pp. 158-160.

French LCA (2005). Research financed by the Ministry

Lhoist-Tradical.

of Agriculture and Fisheries (economic and international

www.lhoist.co.uk/tradical/added-value-hemp.html.

Colliot, Francois (1994). Colliot and L le Roux de Bretagne of Rhone Poulenc. Agrow, 199(7), p.17.

Construire en Chanvre. www.construction-chanvre.asso.fr/.

policies administration). Reference MAP 04 B1 05 01

Construire en Chanvre regles (2007). Reg/es

June 2005. Based on unofficial translation, The Guardian,

professionnelles d'execution. www.sebtp.com.

12 September 2007, p. 8.

Defra (2007). Biomass strategy.

Goodhew S, Griffiths R (2005). Sustainable earth walls to

Department for Communities and Local Government (2008). Code for Sustainable Homes technical guide. www.

planningportal.gov. uk/ uploads/code _for _sust_homes. pdf Deschenaux Ch (March 2001 ). Du produit artisanal

a

la prefabrication industrielle. Proceedings of the Second Assises de la Construction en Chanvre. Ecole d'ingenieurs et

d'architectes de Fribourg, Switzerland.

Hammond G, Jones C (2006). Inventory of carbon and

Vauix en Velin in Lyon. www.entpe.fr/default.htm.

www.limetechnology.co.uk (last consulted November 2006). www.Iimetechnology.co. u k/hemcrete

mortar.

energy (ICE) Version 1.4d Beta. Department of Mechanical

Marinelli J, Bierman-Lyle P (1995). Your natural home.

Engineering, University of Bath.

Little, Brown, & Co., Boston, pp. 81-84.

Hemcore. www.hemcore.co.uk.

Mawditt I (2007). Report on Milton Park building. Living Space Sciences Ltd, Oxford. www.ls-sciences.com.

Hemp Lime Construction Products Association.

ENTPE (Ecole Nationale Des Travaux Public De L'Etat) in

Lime Green. www.lime-green.co.uk.

Livesey P (2007). Reducing the carbon footprint of masonry

pp. 45}-459.

www.hemplime.org.uk.

Howard N, Edwards S, Anderson J (1999). BR370: BRE

Pearson D (1989). The natural house book. Simon &

Schuster/Fireside, New York.

PSI (2006). A systematic approach to estimation of life cycle carbon inventory, carbon footprints and embodied carbon.

Policy Studies Institute. www.psi.org.uk/research/project. asp?project_id= 137 (last consulted November 2006).

Red book live. www.redbooklive.com.

Rode C et al. (2005). Moisture buffering of building materials. Report BYG DTU R-126, Department of Civil

Engineering, Technical University of Denmark.

Roodman OM, Lenssen NA (1995). Building revolution: how ecology and health concerns are transforming construction. World Watch Institute, Washington, DC. Rousseau D, Rea WJ, Enwright J (1989). Your home, your health, and well-being. Hartley & Marks, Vancouver.

Samri D, Arnaud L (2006). Assessment of heat and mass transfers in building porous materials. EPIC, Lyon.

Setac (1991 ). A technical framework for life-cycle

Lime Technology (2006). Tradical Hemcrete overview.

meet the Building Regulations. Energy and Buildings, 37(5),

PAN. www.pan-uk.org.

assessment. Workshop report from the Smugglers Notch,

Vermont, USA, 18-23 August 1990.

Sprayed Concrete Association. www.sca.org.uk.

Significance of fungi in indoor air. Report of a working group.

Health & Welfare Canada, Ottawa, 1987. Canadian Journal of Public Health St Astier. www.stastier.co.uk Straube JF, Burnett EFP (1997). In-service performance of enclosure walls. Volume 1: summary final report. Building

engineering research report, University of Waterloo, 1997.

Straube JF, Burnett EFP (1995). Moisture movement in

building enclosure wall systems. Proceedings of the Thermal

May N (2007a). Breathability in buildings.

Performance of Building Envelopes VI. Clearwater Beach

www.natural-buildings.co.uk.

Florida, 4-7 December 1995, pp. 177-188.

Eureka (2004). www.eureka.be/inaction/AcShowProject.

methodology for environmental profiles of construction

May N (2007b). Naturally efficient. House builder and

Straube JF, Straube V. Acahrya indoor air quality, healthy

do?id=3305.

materials, components and buildings. BRE Bookshop,

developer. www.hbdonline.eu.

buildings, and breathing walls. http://oikos.com.

MMA (2007). www.modernmasonry.co.uk.

Sumacon. www.sumacon.org.

Modcell.

Taylor BJ,Webster R, lmbabi MS (1997). The use of

European Energy Network (2008). Implementation of the EU Energy Performance of Buildings Directive:

a snapshot

report.

European Industrial Hemp Association. www.eiha.org.

Evrard A (2005). Betons de chaux et de chanvre:

Watford.

International Energy Agency. Report annex 24, task 1: hygrothermal properties of building materials. Kumaran MK

(ed.), 1997.

_ hemp%20panel.html

Morton T (2008). Earth masonry. HIS BRE Press,Watford.

ISO 14001. www.iso-14001.org.uk.

phenomenes de transferts de chaleur et de masse et

Jones C (2006). Embodied energy and carbon associated

comportement sous des sollicitations dynamiques. Master

with building materials: inventory of carbon and energy

final report. Universite catholique de Louvain, Belgium,

(ICE). Project website: http://people.bath.ac.uk/cj219/

June 2005.

consulted November 2006). Journal of the Building Limes Forum, 14.

www.modcell.co.uk/ModCell/news

(last

dynamic and diffusive insulation for combined heat recovery and ventilation in buildings. Proceedings of Sustainable Building Conference. Building Environmental Performance

NHBC Foundation (2006). A guide to modern methods of

Analysis Club, 5-6 February 1997, Abingdon, UK,

construction. www.nhbcfoundation.org/Projects.

pp. 168-174.

NNFCC. www.nnfcc.co.uk.

Timusk J (198 7). Design, construction, and performance

Nova Institute. www.nova-institut.de/engl_selbstdarstellung.ht.

of a dynamic wall house. Presented at AIVC Conference,

24 September 1987, Ueberlingen, Germany.

13 REFERENCES ANDNOTES

HEMP LIME CONSTRUCTION Biitschi P-Y. (2004). Utilisation du chanvre pour la

Evrard A (2006). Sorption behaviour of lime-hemp

Kehrer MM, Kunzel HM, Sedlbauer K (2003). Ecological

prefabrication d'elements de construction. PhD thesis.

concrete and its relation to indoor comfort and energy

insulation materials: does sorption moisture affect their

Universite de Moncton, Canada, May 2004.

demand. PLEA2006, The 23rd Conference on Passive

insulation performance? Journal of Thermal Envelope and

and Low-energy Architecture, Geneva, Switzerland,

Building Science, 26(3).

C CaLC. A systematic approach lo estimation of life cycle carbon inventory, carbon footprints and embodied carbon.

6-8 September 2006.

Kioy Stella M (2005). Lime-hemp composites: compressive

Project website: www.surrey.ac.uk/CES/CCalC/ (last

Evrard A (2008). Transient hygrothermal behaviour of

strength and resistance to fungal attacks. MEng dissertation.

consulted November 2006).

lime-hemp materials. PhD in applied science. Universite

Department of Architecture & Civil Engineering, University

catholique de Louvain.

of Bath, May 2005.

Evrard A, De Herde A (2005). Bioclimatic envelopes made

Krusche P,Weig-Krusche M, Althaus D, Gabriel

of lime and hemp concrete. Proceedings of CISBAT2005.

Oekologisches Bauen. Bauverlag, Berlin.

Centre Scientifique et Technique du Batiment.

http://i nternational .cstb.fr.

Cerezo V (2005). Proprietes mecaniques, thermique et acoustique d'uri•materiau

abase de particules

vegetales:

approche experimentale et modelisation theorique, N°ordre:

Ecole Polytechnique Federale de Lausanne, Switzerland, September 2005. www.wufi-pro.com.

Evrard A, De Herde A, Minet J (2006). Dynamical

Lyon (Mecanique, Energetique, Genie Civil, Acoustique).

interactions between heat and mass flows in lime-hemp

acoustiques d'un materiau

abase de particules

vegetates:

approche experimentale et modelisation theorique. PhD

Kuenzel H (1980). Muessen Aussenwaende eatmungsfaehigf

sein? WKSB, November 1980, pp. 1-4.

05 /SAL. PhD thesis. Ecole doctorale and Master MEGA de

Cerezo V (2005). Proprietes mecaniques, thermiques et

I (1982).

concrete. Proceedings of the Third International Building Physics Conference. Concordia University, Canada and the

International Association of Building Physics, August 2005.

Kuenzel HM (1997). WUFI V2.0: simultaneous heat and moisture transport in building components. Fraunhofer

Institute for Building Physics, August 1997.

Lacinski P (1996). Breathing wall, the last straw. Journal of Strawbale Construction, Spring 1996.

thesis. Ecole Nationale des Travaux Publics de l'Etat, France,

Fisk W, Rosenfeld A (1997). Improved productivity and

June 2005.

health from better indoor environments. Center for Building

Levon B.-V (1986). Experimentbyggnade i Norden. Swedish

Science Newsletter. Lawrence-Berkeley Labs.

Council for Building Research, Report T5, pp. 158-160.

French LCA (2005). Research financed by the Ministry

Lhoist-Tradical.

of Agriculture and Fisheries (economic and international

www.lhoist.co.uk/tradical/added-value-hemp.html.

Colliot, Francois (1994). Colliot and L le Roux de Bretagne of Rhone Poulenc. Agrow, 199(7), p.17.

Construire en Chanvre. www.construction-chanvre.asso.fr/.

policies administration). Reference MAP 04 B1 05 01

Construire en Chanvre regles (2007). Reg/es

June 2005. Based on unofficial translation, The Guardian,

professionnelles d'execution. www.sebtp.com.

12 September 2007, p. 8.

Defra (2007). Biomass strategy.

Goodhew S, Griffiths R (2005). Sustainable earth walls to

Department for Communities and Local Government (2008). Code for Sustainable Homes technical guide. www.

planningportal.gov. uk/ uploads/code _for _sust_homes. pdf Deschenaux Ch (March 2001 ). Du produit artisanal

a

la prefabrication industrielle. Proceedings of the Second Assises de la Construction en Chanvre. Ecole d'ingenieurs et

d'architectes de Fribourg, Switzerland.

Hammond G, Jones C (2006). Inventory of carbon and

Vauix en Velin in Lyon. www.entpe.fr/default.htm.

www.limetechnology.co.uk (last consulted November 2006). www.Iimetechnology.co. u k/hemcrete

mortar.

energy (ICE) Version 1.4d Beta. Department of Mechanical

Marinelli J, Bierman-Lyle P (1995). Your natural home.

Engineering, University of Bath.

Little, Brown, & Co., Boston, pp. 81-84.

Hemcore. www.hemcore.co.uk.

Mawditt I (2007). Report on Milton Park building. Living Space Sciences Ltd, Oxford. www.ls-sciences.com.

Hemp Lime Construction Products Association.

ENTPE (Ecole Nationale Des Travaux Public De L'Etat) in

Lime Green. www.lime-green.co.uk.

Livesey P (2007). Reducing the carbon footprint of masonry

pp. 45}-459.

www.hemplime.org.uk.

Howard N, Edwards S, Anderson J (1999). BR370: BRE

Pearson D (1989). The natural house book. Simon &

Schuster/Fireside, New York.

PSI (2006). A systematic approach to estimation of life cycle carbon inventory, carbon footprints and embodied carbon.

Policy Studies Institute. www.psi.org.uk/research/project. asp?project_id= 137 (last consulted November 2006).

Red book live. www.redbooklive.com.

Rode C et al. (2005). Moisture buffering of building materials. Report BYG DTU R-126, Department of Civil

Engineering, Technical University of Denmark.

Roodman OM, Lenssen NA (1995). Building revolution: how ecology and health concerns are transforming construction. World Watch Institute, Washington, DC. Rousseau D, Rea WJ, Enwright J (1989). Your home, your health, and well-being. Hartley & Marks, Vancouver.

Samri D, Arnaud L (2006). Assessment of heat and mass transfers in building porous materials. EPIC, Lyon.

Setac (1991 ). A technical framework for life-cycle

Lime Technology (2006). Tradical Hemcrete overview.

meet the Building Regulations. Energy and Buildings, 37(5),

PAN. www.pan-uk.org.

assessment. Workshop report from the Smugglers Notch,

Vermont, USA, 18-23 August 1990.

Sprayed Concrete Association. www.sca.org.uk.

Significance of fungi in indoor air. Report of a working group.

Health & Welfare Canada, Ottawa, 1987. Canadian Journal of Public Health St Astier. www.stastier.co.uk Straube JF, Burnett EFP (1997). In-service performance of enclosure walls. Volume 1: summary final report. Building

engineering research report, University of Waterloo, 1997.

Straube JF, Burnett EFP (1995). Moisture movement in

building enclosure wall systems. Proceedings of the Thermal

May N (2007a). Breathability in buildings.

Performance of Building Envelopes VI. Clearwater Beach

www.natural-buildings.co.uk.

Florida, 4-7 December 1995, pp. 177-188.

Eureka (2004). www.eureka.be/inaction/AcShowProject.

methodology for environmental profiles of construction

May N (2007b). Naturally efficient. House builder and

Straube JF, Straube V. Acahrya indoor air quality, healthy

do?id=3305.

materials, components and buildings. BRE Bookshop,

developer. www.hbdonline.eu.

buildings, and breathing walls. http://oikos.com.

MMA (2007). www.modernmasonry.co.uk.

Sumacon. www.sumacon.org.

Modcell.

Taylor BJ,Webster R, lmbabi MS (1997). The use of

European Energy Network (2008). Implementation of the EU Energy Performance of Buildings Directive:

a snapshot

report.

European Industrial Hemp Association. www.eiha.org.

Evrard A (2005). Betons de chaux et de chanvre:

Watford.

International Energy Agency. Report annex 24, task 1: hygrothermal properties of building materials. Kumaran MK

(ed.), 1997.

_ hemp%20panel.html

Morton T (2008). Earth masonry. HIS BRE Press,Watford.

ISO 14001. www.iso-14001.org.uk.

phenomenes de transferts de chaleur et de masse et

Jones C (2006). Embodied energy and carbon associated

comportement sous des sollicitations dynamiques. Master

with building materials: inventory of carbon and energy

final report. Universite catholique de Louvain, Belgium,

(ICE). Project website: http://people.bath.ac.uk/cj219/

June 2005.

consulted November 2006). Journal of the Building Limes Forum, 14.

www.modcell.co.uk/ModCell/news

(last

dynamic and diffusive insulation for combined heat recovery and ventilation in buildings. Proceedings of Sustainable Building Conference. Building Environmental Performance

NHBC Foundation (2006). A guide to modern methods of

Analysis Club, 5-6 February 1997, Abingdon, UK,

construction. www.nhbcfoundation.org/Projects.

pp. 168-174.

NNFCC. www.nnfcc.co.uk.

Timusk J (198 7). Design, construction, and performance

Nova Institute. www.nova-institut.de/engl_selbstdarstellung.ht.

of a dynamic wall house. Presented at AIVC Conference,

24 September 1987, Ueberlingen, Germany.

-

APPENDIX 1 RESISTANCE TOCOMPRESSION ANDSTRESS-STRAIN PROPERTIES -

HEMP LIME CONSTRUCTION

Turpin B (1997). Sdg. ASHRAESummer Meeting, 28 June-2

July 1997.

Van Vliet

J (1995). Buildingmaterials(orthe environmentally

hypersensitive.Canada Mortgage and Housing Corporation, Ottawa, 1995.

Walker P,Keable R, Martin

J,Maniatidis

V (2005).

Woolley T (2006). Naturalbuilding:a guide to materialsand techniques. Crowood Press,Wiltshire.

WWF-UK (2003). Contamination:the resultso( the WWF

bio-monitoringsurvey 2003. WWF Godalming, Surrey. www.wwf.org.uk/filelibrary/pdf/biomonitoringresults.pdf.

APPENDIX 1: RESISTANCE TOCOMPRESSION ANDSTRESS-STRAIN PROPERTIES

Yates T (2002). Finalreport on the construction o( the hemp

Rammed earth: design and constructionguidelines. BRE

house at Haverhilt,Suffolk. Report 209-717 (Rev1), BRE,

Press,Watford.

October 2002. www.suffolkhousing.org.

Wilson P (2002). Noise problems in housing. Research study for Defra. BusinessDevelopment Centre for Timber at Napier University.www.cte.napier.ac.uk.

Yu C, Crump D (2007). Indoor airquality criteriafor homes

(orassessinghealth and welt being advances in eco-materials (ICEMB2007). Wang, Songand Abe (eds). Brunel University.

Undertakenby the Universityof Bath

Cylindrical

specimens are generally preferred

for

compression

loading device until failure

compression

testing of hemp lime materials. The

(Fig. A 1.2). Owing to the high deformation

methodology

for compression

stiffness) it is important

testing of hemp

lime has tended to follow procedures for concretes,

established

the direction

load increases. Loading rate, between O.So/oand

mortars and earthen materials.

2% per minute, should be maintained

cylinders are used, whereas in the UK smaller

failure.

100 mm (diameter) x 200 mm (high) cylinders

in

layers, which should replicate in-situ compaction processes, or by uniform static compaction

(as

used by Arnaud and others in France). To date,

characteristics of the material

under load. Typical load-deformation

constant to

Cylinders may be prepared by compaction

to date.

Cylinders are preferred over cubes because of the deformation

in

of the load is also recorded as the

In France, 160 mm (diameter) x 320 mm (high)

have been preferred

(low

that axial deformation

responses

there are no data published on cylinders prepared

for a 100 mm hemp lime cube and a 100 mm

using or replicating pneumatic (sprayed) hemp

diameter (200 mm high) cylinder are compared in

lime construction.

Figure A 1.1. The cylinder test shows a distinct peak

(sprayed) hemp lime reduces the compressive

load (maximum stress), whereas the cube response

strength and stiffness of the material.

demonstrates increasing load resistance at high

The lower density of pneumatic

As with other lime-based materials, strength is

strains following an initial plateau. In both cases

gained significantly

there is considerable ductility in behaviour of the

carbonates. Testing is generally undertaken

material under load.

days which is common for lime-based materials.

Specimens are tested in uniaxial compression under a steadily increasing load in a suitable

with time, as the lime binder

Tests in reference 1 (Fig. A 1.3) show a doubling of 90-day strength after two years.

40 35 30

z

H

-Cube -Cylinder

I I

/

:.. 20

-g

.,,,,./

.3 15 10

0

I

~v

25

5

at 90

~

I.C::--~ 0

5

10

15

20

V

./

---25

30

35

Displacement (mm)

FigA 1.1: Comparison of hemp lime cube and cylinder test response in compression

40

45

50

-

APPENDIX 1 RESISTANCE TOCOMPRESSION ANDSTRESS-STRAIN PROPERTIES -

HEMP LIME CONSTRUCTION

Turpin B (1997). Sdg. ASHRAESummer Meeting, 28 June-2

July 1997.

Van Vliet

J (1995). Buildingmaterials(orthe environmentally

hypersensitive.Canada Mortgage and Housing Corporation, Ottawa, 1995.

Walker P,Keable R, Martin

J,Maniatidis

V (2005).

Woolley T (2006). Naturalbuilding:a guide to materialsand techniques. Crowood Press,Wiltshire.

WWF-UK (2003). Contamination:the resultso( the WWF

bio-monitoringsurvey 2003. WWF Godalming, Surrey. www.wwf.org.uk/filelibrary/pdf/biomonitoringresults.pdf.

APPENDIX 1: RESISTANCE TOCOMPRESSION ANDSTRESS-STRAIN PROPERTIES

Yates T (2002). Finalreport on the construction o( the hemp

Rammed earth: design and constructionguidelines. BRE

house at Haverhilt,Suffolk. Report 209-717 (Rev1), BRE,

Press,Watford.

October 2002. www.suffolkhousing.org.

Wilson P (2002). Noise problems in housing. Research study for Defra. BusinessDevelopment Centre for Timber at Napier University.www.cte.napier.ac.uk.

Yu C, Crump D (2007). Indoor airquality criteriafor homes

(orassessinghealth and welt being advances in eco-materials (ICEMB2007). Wang, Songand Abe (eds). Brunel University.

Undertakenby the Universityof Bath

Cylindrical

specimens are generally preferred

for

compression

loading device until failure

compression

testing of hemp lime materials. The

(Fig. A 1.2). Owing to the high deformation

methodology

for compression

stiffness) it is important

testing of hemp

lime has tended to follow procedures for concretes,

established

the direction

load increases. Loading rate, between O.So/oand

mortars and earthen materials.

2% per minute, should be maintained

cylinders are used, whereas in the UK smaller

failure.

100 mm (diameter) x 200 mm (high) cylinders

in

layers, which should replicate in-situ compaction processes, or by uniform static compaction

(as

used by Arnaud and others in France). To date,

characteristics of the material

under load. Typical load-deformation

constant to

Cylinders may be prepared by compaction

to date.

Cylinders are preferred over cubes because of the deformation

in

of the load is also recorded as the

In France, 160 mm (diameter) x 320 mm (high)

have been preferred

(low

that axial deformation

responses

there are no data published on cylinders prepared

for a 100 mm hemp lime cube and a 100 mm

using or replicating pneumatic (sprayed) hemp

diameter (200 mm high) cylinder are compared in

lime construction.

Figure A 1.1. The cylinder test shows a distinct peak

(sprayed) hemp lime reduces the compressive

load (maximum stress), whereas the cube response

strength and stiffness of the material.

demonstrates increasing load resistance at high

The lower density of pneumatic

As with other lime-based materials, strength is

strains following an initial plateau. In both cases

gained significantly

there is considerable ductility in behaviour of the

carbonates. Testing is generally undertaken

material under load.

days which is common for lime-based materials.

Specimens are tested in uniaxial compression under a steadily increasing load in a suitable

with time, as the lime binder

Tests in reference 1 (Fig. A 1.3) show a doubling of 90-day strength after two years.

40 35 30

z

H

-Cube -Cylinder

I I

/

:.. 20

-g

.,,,,./

.3 15 10

0

I

~v

25

5

at 90

~

I.C::--~ 0

5

10

15

20

V

./

---25

30

35

Displacement (mm)

FigA 1.1: Comparison of hemp lime cube and cylinder test response in compression

40

45

50

APPENDIX 1 RESISTANCE TOCOMPRESSION ANDSTRESS-STRAIN PROPERTIES

Previous research in France indicates that hemp

Hemp : lime binder ratio (greater binder

lime under moderate stresses initial loading is

content increases density, strength and stiffness,

inelastic, ie it is does not fully recover when load is

but reduces thermal resistance)

removed. However, on reapplication of load material

Inclusion of sand in mix (increased density

behaviour is elastic or near elastic. The initial service

stiffens mix)

loading compresses (densifies) the open structure.

Curing conditions

Therefore, if hemp lime is to be used in load-bearing

Density

applications, this initial densification would need to

Age

be accommodated, either through a precompression,

Moisture content at testing.

as in straw bale for example, or by detailing that can accommodate this movement.

The results from hemp lime cylinder tests,

Factors influencing compression behaviour:

undertaken

•

Specimen geometry and size (use cylinder ratio

(Kioy, 2005), are compared

2 : 1 height : diameter)

Table A1 .1.

at the University of Bath in 2005 in Figure A1 .4 and

TableA 1. 1: Comparative compression performance of hemp lime materials (Kioy, 2005) Mix

Mix proportions* (by volume) 1 part NHL 3.5 : 3 parts Hemcore:

0.9 water

1/) 1/)

3

1 part NHL 3.5 : 3 parts Hemcore : 0.5 parts sharp sand: 0.9 water

700

1.15

22.0%

4

1 part Tradical PF 70 : 3 parts Hemcore : 0.7 water

610

1.98

15.0%

5

1 part Tradical PF 70 : 3 parts Hemcore : 0.5 parts sand: 0.7 water

830

1.88

10.0%

*NHL = Non-hydraulic lime

Mix1 Mix2 Mix3 Mix4 Mix5

TableA 1.2: Comparison of hemp lime properties with other materials Material

Density

Ultimate

Strain at

Maximum allowable

Elastic

(kg/m3 )

compressive strength (N/mm 2 )

ultimate compressive

design compressive stress

modulus (N/mm 2 )

350-600

0.5-1.5

5-20

110

0.5

>10

Unfired earth

1500-2000

1-5

Lime render (at 90 da s)

1800-2000

1-5

350

20

1/)

l!:! 1.0 a.

E

Hemp lime (at 90 da s)

0 0

iii

Straw bale

0.5

0 10

15

20

25

30

35

Axial strain(%)

C14 softwood FigA 1.3: Stress-strain responses of hemp lime cylinders under compression loading

22.5% 25.0%

Q)

5

1.15 1.01

> 'iii

0

620 500

l!:!

1ii 1.5

J

Axial strain at maximum load (% strain)

1 part NHL 3.5 : 3 parts lsochanvre : 0.9 water

2.5

«I 2.0 a. ~

Ultimate stress (N/mm 2)

2

Fig A 1.2: Hemp lime cylinder test in compression

-

Dry density (kg/m 3 )

strength (%)

(N/mm

2)

Not specified: 0.25 at 1% strain

0.017 at 1% strain

0.2

20-30 1.5 100-1000

0.3-0.5 5 (parallel to grain)

6000

APPENDIX 1 RESISTANCE TOCOMPRESSION ANDSTRESS-STRAIN PROPERTIES

Previous research in France indicates that hemp

Hemp : lime binder ratio (greater binder

lime under moderate stresses initial loading is

content increases density, strength and stiffness,

inelastic, ie it is does not fully recover when load is

but reduces thermal resistance)

removed. However, on reapplication of load material

Inclusion of sand in mix (increased density

behaviour is elastic or near elastic. The initial service

stiffens mix)

loading compresses (densifies) the open structure.

Curing conditions

Therefore, if hemp lime is to be used in load-bearing

Density

applications, this initial densification would need to

Age

be accommodated, either through a precompression,

Moisture content at testing.

as in straw bale for example, or by detailing that can accommodate this movement.

The results from hemp lime cylinder tests,

Factors influencing compression behaviour:

undertaken

•

Specimen geometry and size (use cylinder ratio

(Kioy, 2005), are compared

2 : 1 height : diameter)

Table A1 .1.

at the University of Bath in 2005 in Figure A1 .4 and

TableA 1. 1: Comparative compression performance of hemp lime materials (Kioy, 2005) Mix

Mix proportions* (by volume) 1 part NHL 3.5 : 3 parts Hemcore:

0.9 water

1/) 1/)

3

1 part NHL 3.5 : 3 parts Hemcore : 0.5 parts sharp sand: 0.9 water

700

1.15

22.0%

4

1 part Tradical PF 70 : 3 parts Hemcore : 0.7 water

610

1.98

15.0%

5

1 part Tradical PF 70 : 3 parts Hemcore : 0.5 parts sand: 0.7 water

830

1.88

10.0%

*NHL = Non-hydraulic lime

Mix1 Mix2 Mix3 Mix4 Mix5

TableA 1.2: Comparison of hemp lime properties with other materials Material

Density

Ultimate

Strain at

Maximum allowable

Elastic

(kg/m3 )

compressive strength (N/mm 2 )

ultimate compressive

design compressive stress

modulus (N/mm 2 )

350-600

0.5-1.5

5-20

110

0.5

>10

Unfired earth

1500-2000

1-5

Lime render (at 90 da s)

1800-2000

1-5

350

20

1/)

l!:! 1.0 a.

E

Hemp lime (at 90 da s)

0 0

iii

Straw bale

0.5

0 10

15

20

25

30

35

Axial strain(%)

C14 softwood FigA 1.3: Stress-strain responses of hemp lime cylinders under compression loading

22.5% 25.0%

Q)

5

1.15 1.01

> 'iii

0

620 500

l!:!

1ii 1.5

J

Axial strain at maximum load (% strain)

1 part NHL 3.5 : 3 parts lsochanvre : 0.9 water

2.5

«I 2.0 a. ~

Ultimate stress (N/mm 2)

2

Fig A 1.2: Hemp lime cylinder test in compression

-

Dry density (kg/m 3 )

strength (%)

(N/mm

2)

Not specified: 0.25 at 1% strain

0.017 at 1% strain

0.2

20-30 1.5 100-1000

0.3-0.5 5 (parallel to grain)

6000

APPENDIX 2 THERMAL M6ASUREMENTS ONLIME ANDHEMP MIXTURES

HEMP LIME CONSTRUCTION

1.25

APPENDIX 2: THERMAL MEASUREMENTS ONLIMEANDHEMPMIXTURES {SUMMARY)

1.00

-;;;-0.75

Undertakenby the Universityof Plymouth

Q.

6

"' ~

"' ...

0.50

.

,

TableA2. 1: Lime Technology Ltd samples (24 July 2006)

Cl)

Summary

0.25

Confidence (%)

Mean measured - W/m K (11)

1) Lime hemp sample A

0.142

0.66

2) Lime hemp sample B

0.148

1.59

0.00 0

5

10 Strain(%)

15

'gA 1.4: Results from hemp lime cylinder tests, undertaken at the University of Bath in 2005 (Kioy, 2005)

20

TableA2.2: Tradical Hemcrete in-situ at Lime Technology Ltd, Abingdon, and samples at Higher Lank (21 August 2006 to 29 August 2006) Summary

Mean measured - W/m K (11)

Confidence (%)

1) Tradical Hemcrete, internal, wall base

0.127

2.40

2) Tradical Hemcrete, external, wall base

0.141

4.39

3) Tradical Hemcrete, internal, wall head

0.189

2.03

0.176

4.40

0.131

0.56

4) Tradical Hemcrete, external, wall head 5) Tradical Hemcrete sample, cylinder 368.6 kglm 6) Tradical Hemcrete sample, cube 562 kglm

3

3

0.178

1.40

3

0.913

0.37

8) Compressed earth hole 2, 2,032 kglm 3

0.833

1.92

9) Tradical Hemcrete sample, cylinder 363.7 kglm 3, dried

0.129

3.03

7) Compressed earth hole 1, 2,032 kglm

TableA2.3: Cast hemp lime at Hartest (5 De~~m·b~r 2006)': Summary

Mean measured - W/m K (A)

· · · Repeatability

1) East, internal low

0.072

0.29

2) East, external low

0.088

0.22

3) East, internal high

0.094

0.46

4) East, external high

0.091

0.86

5) West, internal low

0.075

0.95

6) West, external low

0.099

1.89

7) West, internal high

0.076

0.46

8) West, external high

0.075

0.76

±

(%)

APPENDIX 2 THERMAL M6ASUREMENTS ONLIME ANDHEMP MIXTURES

HEMP LIME CONSTRUCTION

1.25

APPENDIX 2: THERMAL MEASUREMENTS ONLIMEANDHEMPMIXTURES {SUMMARY)

1.00

-;;;-0.75

Undertakenby the Universityof Plymouth

Q.

6

"' ~

"' ...

0.50

.

,

TableA2. 1: Lime Technology Ltd samples (24 July 2006)

Cl)

Summary

0.25

Confidence (%)

Mean measured - W/m K (11)

1) Lime hemp sample A

0.142

0.66

2) Lime hemp sample B

0.148

1.59

0.00 0

5

10 Strain(%)

15

'gA 1.4: Results from hemp lime cylinder tests, undertaken at the University of Bath in 2005 (Kioy, 2005)

20

TableA2.2: Tradical Hemcrete in-situ at Lime Technology Ltd, Abingdon, and samples at Higher Lank (21 August 2006 to 29 August 2006) Summary

Mean measured - W/m K (11)

Confidence (%)

1) Tradical Hemcrete, internal, wall base

0.127

2.40

2) Tradical Hemcrete, external, wall base

0.141

4.39

3) Tradical Hemcrete, internal, wall head

0.189

2.03

0.176

4.40

0.131

0.56

4) Tradical Hemcrete, external, wall head 5) Tradical Hemcrete sample, cylinder 368.6 kglm 6) Tradical Hemcrete sample, cube 562 kglm

3

3

0.178

1.40

3

0.913

0.37

8) Compressed earth hole 2, 2,032 kglm 3

0.833

1.92

9) Tradical Hemcrete sample, cylinder 363.7 kglm 3, dried

0.129

3.03

7) Compressed earth hole 1, 2,032 kglm

TableA2.3: Cast hemp lime at Hartest (5 De~~m·b~r 2006)': Summary

Mean measured - W/m K (A)

· · · Repeatability

1) East, internal low

0.072

0.29

2) East, external low

0.088

0.22

3) East, internal high

0.094

0.46

4) East, external high

0.091

0.86

5) West, internal low

0.075

0.95

6) West, external low

0.099

1.89

7) West, internal high

0.076

0.46

8) West, external high

0.075

0.76

±

(%)

USEFUL CONTACTS

USEFUL CONTACTS HempLimeConstruction ProductsAssociation www.hemplime.org.uk

Architectureet Climat Dr Arnaud Evrard, lr Architecte Universite catholique de Louvain Place du Levant, 1 B-1348 Louvai n-la-Neuve Belgium Tel: +32 (0)10472160 Fax: +32 (0)10472150 Web: www.climat.arch.ucl.ac.be

Balthazardand CotteBatiment www.balthazard.com 15, rue Henri Dagalier 38030 Grenoble Cedex 2 France Tel: +33 (0)476 335800 Fax: +33 (0)476 335833 Tel: +33(0)381474011 Fax: +33(0)381474019

BRECentrefor InnovativeConstruction Materials Director, Professor Peter Walker Department of Architecture and Civil Engineering University of Bath Bath BA2 7AY Tel: 01225 386646 Fax: 01225 386691 Web: www.bath.ac.uk/bre

BuildingLimesForum Glasite Meeting House 33 Barony Street Edinburgh EH3 6NX Email: admin@buildinglimesforum.org.uk Web: www.buildinglimesforum.org.uk

Centrefor AlternativeTechnology Graduate School of the Environment Machynlleth Powys SY20 9AZ Tel: 01654 705983 Web: http://gradschool.cat.org.uk/graduateschool

Construire en Chanvre .

BP 6 F-89 150 Saint Valerien France Fax: +33 (0)386 977287 Email: construire.chanvre@wanadoo.fr Web: www.construction-chanvre.asso.fr

Galeforce CivilEngineering Ltd Tel: 0114 2377044 Fax: 0114 2372036 Contact: John Aveling Web: www.galeforce.co.uk

HemcoreLtd Latchmore Bank Little Hallingbury Bishops Stortford CM22 7PJ Tel: 01279 504466 Fax: 01279 755395 Email: info@hemcore.co.uk Web: www.hemcore.co.uk

USEFUL CONTACTS

USEFUL CONTACTS HempLimeConstruction ProductsAssociation www.hemplime.org.uk

Architectureet Climat Dr Arnaud Evrard, lr Architecte Universite catholique de Louvain Place du Levant, 1 B-1348 Louvai n-la-Neuve Belgium Tel: +32 (0)10472160 Fax: +32 (0)10472150 Web: www.climat.arch.ucl.ac.be

Balthazardand CotteBatiment www.balthazard.com 15, rue Henri Dagalier 38030 Grenoble Cedex 2 France Tel: +33 (0)476 335800 Fax: +33 (0)476 335833 Tel: +33(0)381474011 Fax: +33(0)381474019

BRECentrefor InnovativeConstruction Materials Director, Professor Peter Walker Department of Architecture and Civil Engineering University of Bath Bath BA2 7AY Tel: 01225 386646 Fax: 01225 386691 Web: www.bath.ac.uk/bre

BuildingLimesForum Glasite Meeting House 33 Barony Street Edinburgh EH3 6NX Email: admin@buildinglimesforum.org.uk Web: www.buildinglimesforum.org.uk

Centrefor AlternativeTechnology Graduate School of the Environment Machynlleth Powys SY20 9AZ Tel: 01654 705983 Web: http://gradschool.cat.org.uk/graduateschool

Construire en Chanvre .

BP 6 F-89 150 Saint Valerien France Fax: +33 (0)386 977287 Email: construire.chanvre@wanadoo.fr Web: www.construction-chanvre.asso.fr

Galeforce CivilEngineering Ltd Tel: 0114 2377044 Fax: 0114 2372036 Contact: John Aveling Web: www.galeforce.co.uk

HemcoreLtd Latchmore Bank Little Hallingbury Bishops Stortford CM22 7PJ Tel: 01279 504466 Fax: 01279 755395 Email: info@hemcore.co.uk Web: www.hemcore.co.uk

HEMP LIME CONSTRUCTION

LhoistUK

fN0EX

Quickseal

Hindlow

Unit 2

Buxton

7 Buntsford Park Road Bromsgrove Worcester

Derbyshire SK17 0EL Tel: 01298 768666

B60 3DX

Fax: 01298 768601

Tel: 01527 881933

Web: www.lhoist.eo.uk/www.lhoist.eom

Fax: 01527 881932

www.tradical.co.uk

Email: Bromsgrove@quickseal.fsnet.co.uk

LimeGreenProductLtd

RachelBevanArchitects

accreditation 17

Coates Kilns

17 A Main Street, Saintfield

acoustic performance 75-6

cellulose, sources of 2, 9

Adnams brewery warehouse and distribution

cement

TF13 6DC

Ballynahinch BT24 7AA

air tightness 58, 60-1, 68

Tel: 01952 728 611

Tel: 028 9751 2851

Arnaud, Laurent 68

Centre for Alternative Technology, Machynlleth,

Barn conversion, Croxley Green, Hertfordshire 19, 22, 39

Chalons-en-Champagne, France 46

Stretton Road Much Wenlock

Fax: 01952 728 361

centre, Suffolk 9, 19, 20, 42, 58

Fax: 028 97512851 Email: woolley.tom@virgin.net

LimeTechnology Ltd

INDEX

Web: www.bevanarchitects.com

Unit 126, Milton Park

cavity walls 60

carbon emissions 82 comparison with lime 50 WISE building 19, 26, 73

Batichanvre 7, 50, 52

cladding 53

bending, resistance to 71-2

Clay Fields, Suffolk 19, 25

Abingdon

RichesHawleyMikhailArchitectsLtd

blocks, hemp lime construction 12, 42

Code for Sustainable Homes 1, 2-3, 56, 91-2

OX14 4SA

Unit 29

costs, hemp lime construction 94

Tel: 0845 603 1143

1-13 Adler Street

Brakspear summerhouse, Worcester 19, 24 BRE

Fax: 0845 634 1560

London E1 1 EC

environmental profiles 79-80

damp-proof course 43, 44, 74-5

Email: info@limetechnology.co.uk

Tel: 020 7247 6418

study of Haverhill houses 5, 41, 59, 76

De Herde, A. 54, 55, 63, 65

Web: www.limetechnology.co.uk

Fax: 020 7377 5791

Breathe hemp insulation 88

Diffutherm 85, 88

Email: info@rhmarchitects.com

building materials

drying times 10, 41-2

ModeceArchitects

Web: www.rhmarchitects.com

Fosters

government policy 2-3 natural products 1-3, 85-9

embodied carbon 78-9, 80

Hartest

ShotcreteServicesLtd

non-food crops 1-2, 9-10, 27-9, 86

ENTPE,France 68, 76

Bury St Edmunds

renewable 1-3, 9-10

environmental impacts, hemp lime 77-84, 94

IP29 4ET

Contact: Stuart Manning Email: stuart. manning@shotcrete.co. uk

synthetic 1

environmental product declarations (EPDs) 80

Tel: 01284 830085

Tel: 01634 717 380

Neb: www.modece.com

Fax: 01634 71 7 480

air leakage 68

Web: www.shotcrete.co.uk

fire regulations 75

fhe NationalNon-Food CropsCentre

Building Regulations

Evrard, A. 54, 55, 63, 65 existing buildings, renovating 15, 45-6

site preparation 74-5

Fermacell 85

sound insulation 75-6

finishes 14, 44

3iocentre

SingletonBirchLtd

fork Science Park

Melton Ross Quarries

thermal standards 5 7, 60

fire regulations 75

nnovation Way

Barnetby DN38 6AE

ventilation 55

fixings 44, 72

-feslington {ork Y010 5DC

Tel: 01652 686000

calcium carbonate, lime production 51

footings 43, 73

rel: 01904 435182

Fax: 01653 686081

Canaflex 88

foundations 43, 73

=ax: 01904 435345

Emai I: sales@singleton birch .co. u k

carbon

France, hemp lime construction 3, 4

Neb: www.nnfcc.co.uk

floors 43, 74-5

embodied 78-9, 80 emissions 82, 93

government policy, sustainable building 2-3, 91-2

sequestration 9, 50, 77, 81-3, 94

green board 87

zero-carbon buildings 1, 91-2

Creenlight project, Suffolk 19, 21

Carpenter House, Suffolk 19, 22, 59-60 Carpenter, Ralph 16, 22, 31, 43, 73, 74-5

gypsum plasterboard 85

HEMP LIME CONSTRUCTION

LhoistUK

fN0EX

Quickseal

Hindlow

Unit 2

Buxton

7 Buntsford Park Road Bromsgrove Worcester

Derbyshire SK17 0EL Tel: 01298 768666

B60 3DX

Fax: 01298 768601

Tel: 01527 881933

Web: www.lhoist.eo.uk/www.lhoist.eom

Fax: 01527 881932

www.tradical.co.uk

Email: Bromsgrove@quickseal.fsnet.co.uk

LimeGreenProductLtd

RachelBevanArchitects

accreditation 17

Coates Kilns

17 A Main Street, Saintfield

acoustic performance 75-6

cellulose, sources of 2, 9

Adnams brewery warehouse and distribution

cement

TF13 6DC

Ballynahinch BT24 7AA

air tightness 58, 60-1, 68

Tel: 01952 728 611

Tel: 028 9751 2851

Arnaud, Laurent 68

Centre for Alternative Technology, Machynlleth,

Barn conversion, Croxley Green, Hertfordshire 19, 22, 39

Chalons-en-Champagne, France 46

Stretton Road Much Wenlock

Fax: 01952 728 361

centre, Suffolk 9, 19, 20, 42, 58

Fax: 028 97512851 Email: woolley.tom@virgin.net

LimeTechnology Ltd

INDEX

Web: www.bevanarchitects.com

Unit 126, Milton Park

cavity walls 60

carbon emissions 82 comparison with lime 50 WISE building 19, 26, 73

Batichanvre 7, 50, 52

cladding 53

bending, resistance to 71-2

Clay Fields, Suffolk 19, 25

Abingdon

RichesHawleyMikhailArchitectsLtd

blocks, hemp lime construction 12, 42

Code for Sustainable Homes 1, 2-3, 56, 91-2

OX14 4SA

Unit 29

costs, hemp lime construction 94

Tel: 0845 603 1143

1-13 Adler Street

Brakspear summerhouse, Worcester 19, 24 BRE

Fax: 0845 634 1560

London E1 1 EC

environmental profiles 79-80

damp-proof course 43, 44, 74-5

Email: info@limetechnology.co.uk

Tel: 020 7247 6418

study of Haverhill houses 5, 41, 59, 76

De Herde, A. 54, 55, 63, 65

Web: www.limetechnology.co.uk

Fax: 020 7377 5791

Breathe hemp insulation 88

Diffutherm 85, 88

Email: info@rhmarchitects.com

building materials

drying times 10, 41-2

ModeceArchitects

Web: www.rhmarchitects.com

Fosters

government policy 2-3 natural products 1-3, 85-9

embodied carbon 78-9, 80

Hartest

ShotcreteServicesLtd

non-food crops 1-2, 9-10, 27-9, 86

ENTPE,France 68, 76

Bury St Edmunds

renewable 1-3, 9-10

environmental impacts, hemp lime 77-84, 94

IP29 4ET

Contact: Stuart Manning Email: stuart. manning@shotcrete.co. uk

synthetic 1

environmental product declarations (EPDs) 80

Tel: 01284 830085

Tel: 01634 717 380

Neb: www.modece.com

Fax: 01634 71 7 480

air leakage 68

Web: www.shotcrete.co.uk

fire regulations 75

fhe NationalNon-Food CropsCentre

Building Regulations

Evrard, A. 54, 55, 63, 65 existing buildings, renovating 15, 45-6

site preparation 74-5

Fermacell 85

sound insulation 75-6

finishes 14, 44

3iocentre

SingletonBirchLtd

fork Science Park

Melton Ross Quarries

thermal standards 5 7, 60

fire regulations 75

nnovation Way

Barnetby DN38 6AE

ventilation 55

fixings 44, 72

-feslington {ork Y010 5DC

Tel: 01652 686000

calcium carbonate, lime production 51

footings 43, 73

rel: 01904 435182

Fax: 01653 686081

Canaflex 88

foundations 43, 73

=ax: 01904 435345

Emai I: sales@singleton birch .co. u k

carbon

France, hemp lime construction 3, 4

Neb: www.nnfcc.co.uk

floors 43, 74-5

embodied 78-9, 80 emissions 82, 93

government policy, sustainable building 2-3, 91-2

sequestration 9, 50, 77, 81-3, 94

green board 87

zero-carbon buildings 1, 91-2

Creenlight project, Suffolk 19, 21

Carpenter House, Suffolk 19, 22, 59-60 Carpenter, Ralph 16, 22, 31, 43, 73, 74-5

gypsum plasterboard 85

___________________________________

HEMP LIME CONSTRUCTION

Haverhill social housing, Suffolk

finishes 14, 44

Milton Park building, Oxfordshire (Lime Technology offices)

,_No_Ex_llll

target emission rate (TER) 57 thermal bridges 57--8, 69

construction of 6, 9, 22, 39, 41

fire resistance 75

sound insulation 76 thermal performance 5, 59, 68

fixings 44, 72 footings and floor slabs 43, 74-5

water spray tests 53

foundations 43, 73

miscanthus 29

thermal diffusivity 66-7

health and well-being 55, 56-7, 94

history of 4, 9

MMC see modern methods of construction

thermal effusivity 67, 68

heat transfer 65-6

masonry construction 93-4

Modcell panels 40, 86

thermal mass 58

openings in walls 73

modern methods of construction (MMC) 93-4

thermal performance 5-6, 57-61, 63-9

Hemcore 6

prefabrication 40

mould 55, 56, 94

timber

Hemcrete see Tradical

roofs 43, 73

Moy lsover 88

hemp for building use 6, 49

shuttered, cast and tamped walls 11-12, 41

see also thermal performance

construction of 9, 19, 23

thermal capacity 65

thermal performance 58, 60, 69

thermal comfort 58-9, 68

cladding for external walls 53

techniques 4-5, 11, 31-47

National Non-Food Crops Centre (NNFCC) 1, 3, 5

environmental impacts 83

timber frame buildings 12, 39, 47, 73, 93-4

natural hydraulic lime (NHL) 6

growth and processing 10, 16, 27-9

training courses 31

natural products, building materials 85-9

insulation materials 88

walls 11-12, 39-42, 73

NBT hemp batts 88

particleboard 87--8

wet and dry methods 40

hempcrete 7, 10 hemp lime acoustic performance 75-6

Hemp Lime Construction Products Association (HLCPA) 5, 7, 17, 94

as building material 2, 9

NHL see natural hydraulic lime

thermal properties 69 timber frame construction 12, 39, 47, 73, 93-4 thermal performance 57--8 Tradical exhibition stand 19, 24

NNFCC see National Non-Food Crops Centre

Hemcrete 17, 23, 41, 63-9

non-food crops, as building materials 1-2, 9-10, 27-9, 86

lime binder 50, 51 products 6, 7

Heraklith 85, 87 Orwell Housing Association 19, 25

training courses, hemp lime construction 31 U-values

bending resistance 71-2

historic buildings, renovations 15, 45-6

carbon sequestration 9, 50, 77, 81-3, 94

house extension, Oxfordshire 19, 26

comparison with wood 69

humidity 55-7, 74-5

Pavatex 85

hurd 7

Pavatherm Plus 88

Adnams brewery warehouse 20

durability 53-4

pest resistance 56

Haverhill houses 59

environmental impacts 77-84, 94

indoor air quality 56-7

Pield Heath Avenue, Hillingdon, London 19, 22

Lime Technology Ltd offices 23

insulation

plaster 47

thermal performance measure 57, 59-60, 61, 63

drying 10, 41-2

health benefits 55, 56-7, 94 life cycle assessment(LCA) 77-82, 84

hemp lime walls 60

mixing of 10-11, 16, 41, 52

natural materials 85

plaster 47

synthetic 1, 85-6

plasterboard 85 ventilation 55-7 radon, barriers 43, 74 walls

lnvotek 88

rendering 46, 86

lsochanvre 6, 31, 49

renovations, of existing buildings 15, 45-6

cavity walls 60

shear resistance 72

lsolair 88

Riches Hawley Mikhail Architects Ltd 25, 102

hemp lime construction 11-12, 39-42

spray-applied 14, 41

lsonat 88

roofs 43, 73

properties of 9 renovation work 15, 45-6

structural performance 71, 72-3 supply of materials 6-7, 15-16

internal 73 water absorption, hemp lime 42, 53, 54-5, 63-4, 94

kenaf 7, 29, 30

thermal mass and comfort 58-9

Sasmox 85

Wilson, Peter 76

self-build 16, 41

WISE building, Machynlleth 19, 26, 73 wood fibre

thermal performance 5-6, 57-61, 63-9

life cycle assessments(LCA) 3, 77-82, 84

shear, resistance to 72

ventilation 55-7

life cycle carbon inventory (LCCI) 77, 78, 80

shiv 6, 7, 9, 28

boards 85

water absorption 42, 53, 54-5, 63-4, 94

lime binder

shive see shiv

insulation 85, 88

comparison with cement 50

shuttering, for use with hemp lime 85

definition 7

SIPSsee structural insulated panels

accreditation 17

production of 51

sound insulation 75-6

advantages of 91-5

types of 6-7, 50

Sprayed Concrete Association 1, 7

see also hemp lime

Steico 88

see also hemp; lime binder 1emp lime construction

air tightness 58, 60-1, 68 blocks 12, 42

limecrete 43, 73

straw bale buildings 86

case examples 19-26

Lime Technology Ltd 6, 31

strawboard 88

cladding 53

see also Milton Park building

damp-proof membranes 43, 44, 74-5

structural insulated panels (SIPS) 40, 58 sustainable building, government policy 2-3, 91-2

costs 94 masonry construction, hemp lime 93-4

wood wool boards 85, 87 York Eco-Depot 86 zero-carbon buildings 1, 91-2

___________________________________

HEMP LIME CONSTRUCTION

Haverhill social housing, Suffolk

finishes 14, 44

Milton Park building, Oxfordshire (Lime Technology offices)

,_No_Ex_llll

target emission rate (TER) 57 thermal bridges 57--8, 69

construction of 6, 9, 22, 39, 41

fire resistance 75

sound insulation 76 thermal performance 5, 59, 68

fixings 44, 72 footings and floor slabs 43, 74-5

water spray tests 53

foundations 43, 73

miscanthus 29

thermal diffusivity 66-7

health and well-being 55, 56-7, 94

history of 4, 9

MMC see modern methods of construction

thermal effusivity 67, 68

heat transfer 65-6

masonry construction 93-4

Modcell panels 40, 86

thermal mass 58

openings in walls 73

modern methods of construction (MMC) 93-4

thermal performance 5-6, 57-61, 63-9

Hemcore 6

prefabrication 40

mould 55, 56, 94

timber

Hemcrete see Tradical

roofs 43, 73

Moy lsover 88

hemp for building use 6, 49

shuttered, cast and tamped walls 11-12, 41

see also thermal performance

construction of 9, 19, 23

thermal capacity 65

thermal performance 58, 60, 69

thermal comfort 58-9, 68

cladding for external walls 53

techniques 4-5, 11, 31-47

National Non-Food Crops Centre (NNFCC) 1, 3, 5

environmental impacts 83

timber frame buildings 12, 39, 47, 73, 93-4

natural hydraulic lime (NHL) 6

growth and processing 10, 16, 27-9

training courses 31

natural products, building materials 85-9

insulation materials 88

walls 11-12, 39-42, 73

NBT hemp batts 88

particleboard 87--8

wet and dry methods 40

hempcrete 7, 10 hemp lime acoustic performance 75-6

Hemp Lime Construction Products Association (HLCPA) 5, 7, 17, 94

as building material 2, 9

NHL see natural hydraulic lime

thermal properties 69 timber frame construction 12, 39, 47, 73, 93-4 thermal performance 57--8 Tradical exhibition stand 19, 24

NNFCC see National Non-Food Crops Centre

Hemcrete 17, 23, 41, 63-9

non-food crops, as building materials 1-2, 9-10, 27-9, 86

lime binder 50, 51 products 6, 7

Heraklith 85, 87 Orwell Housing Association 19, 25

training courses, hemp lime construction 31 U-values

bending resistance 71-2

historic buildings, renovations 15, 45-6

carbon sequestration 9, 50, 77, 81-3, 94

house extension, Oxfordshire 19, 26

comparison with wood 69

humidity 55-7, 74-5

Pavatex 85

hurd 7

Pavatherm Plus 88

Adnams brewery warehouse 20

durability 53-4

pest resistance 56

Haverhill houses 59

environmental impacts 77-84, 94

indoor air quality 56-7

Pield Heath Avenue, Hillingdon, London 19, 22

Lime Technology Ltd offices 23

insulation

plaster 47

thermal performance measure 57, 59-60, 61, 63

drying 10, 41-2

health benefits 55, 56-7, 94 life cycle assessment(LCA) 77-82, 84

hemp lime walls 60

mixing of 10-11, 16, 41, 52

natural materials 85

plaster 47

synthetic 1, 85-6

plasterboard 85 ventilation 55-7 radon, barriers 43, 74 walls

lnvotek 88

rendering 46, 86

lsochanvre 6, 31, 49

renovations, of existing buildings 15, 45-6

cavity walls 60

shear resistance 72

lsolair 88

Riches Hawley Mikhail Architects Ltd 25, 102

hemp lime construction 11-12, 39-42

spray-applied 14, 41

lsonat 88

roofs 43, 73

properties of 9 renovation work 15, 45-6

structural performance 71, 72-3 supply of materials 6-7, 15-16

internal 73 water absorption, hemp lime 42, 53, 54-5, 63-4, 94

kenaf 7, 29, 30

thermal mass and comfort 58-9

Sasmox 85

Wilson, Peter 76

self-build 16, 41

WISE building, Machynlleth 19, 26, 73 wood fibre

thermal performance 5-6, 57-61, 63-9

life cycle assessments(LCA) 3, 77-82, 84

shear, resistance to 72

ventilation 55-7

life cycle carbon inventory (LCCI) 77, 78, 80

shiv 6, 7, 9, 28

boards 85

water absorption 42, 53, 54-5, 63-4, 94

lime binder

shive see shiv

insulation 85, 88

comparison with cement 50

shuttering, for use with hemp lime 85

definition 7

SIPSsee structural insulated panels

accreditation 17

production of 51

sound insulation 75-6

advantages of 91-5

types of 6-7, 50

Sprayed Concrete Association 1, 7

see also hemp lime

Steico 88

see also hemp; lime binder 1emp lime construction

air tightness 58, 60-1, 68 blocks 12, 42

limecrete 43, 73

straw bale buildings 86

case examples 19-26

Lime Technology Ltd 6, 31

strawboard 88

cladding 53

see also Milton Park building

damp-proof membranes 43, 44, 74-5

structural insulated panels (SIPS) 40, 58 sustainable building, government policy 2-3, 91-2

costs 94 masonry construction, hemp lime 93-4

wood wool boards 85, 87 York Eco-Depot 86 zero-carbon buildings 1, 91-2

ABOUTTHISBOOK Hemp lime is a composite construction material that can be used for walls, insulation of roofs and floors and as part of timber-framed buildings. It provides very good thermal and acoustic performance, and offers a genuinely zero-carbon contribution to sustainable construction. Hemp masonry is breathable and is able to absorb and emit moisture, leading to much healthier buildings. Comprehensive guidance on using this novel material for housing and low-rise buildings is given for the first time in this book, which is full of practical information on materials, design and construction. It is fully illustrated and includes case studies and design details, and explains how the use of hemp based material can capture and store carbon dioxide in the fabric of buildings.

The guide is the output from a Defra-funded study commissioned by the National Non-Food Crops Centre.

From the Foreword

by Marianne

Suhr:

"This book is packed full of all the information you could need. I only wish it had been available before I embarked on my own hemp lime building projects"

brepress

IHS BRE Press, Willoughby Road Bracknell, Berkshire RG12 8FB www.ihsbrepress.com

ISBN 978-1-84806-033-3

EP85 9

33

LimeHemp andRicel:luskBased Concretes forBuilding ~---Envelopes

Published under the auspices of EPNOE*Springerbriefs in Biobased polymers covers all aspects of biobased polymer science, from the basis of this field starting from the living species in which they are synthetized (such as genetics, agronomy, plant biology) to the many applications they are used in (such as food, feed, engineering, construction, health, ... ) through to isolation and characterization, biosynthesis, biodegradation, chemical modifications, physical, chemical, mechanical and structural characterizations or biomimetic applications. All biobased polymers in all application sectors are welcome, either those produced in living species (like polysaccharides, proteins, Iignin, ... ) or those that are rebuilt by chemists as in the case of many bioplastics.

Under the editorship of Patrick Navard and a panel of experts, the series will include contributions from many of the world's most authoritative biobased polymer scientists and professionals. Readers will gain an understanding of how given biobased polymers are made and what they can be used for. They will also be able to widen their knowledge and find new opportunities due to the multidisciplinary contributions.

This series is aimed at advanced undergraduates, academic and industrial researchers and professionals studying or using biobased polymers. Each brief will bear a general introduction enabling any reader to understand its topic.

Morgan Chabannes. Eric Garcia-Diaz Laurent Clerc. Jean-Charles Benezet Frederic Becquart

Lime Hemp and Rice Husk-Based Concretes for Building Envelopes

*EPNOE The European Polysaccharide Network of Excellence (www.epnoe.eu) is a research and education network connecting academic, research institutions and companies focusing on polysaccharides and polysaccharide-related research and business.

More information about this series at http://www.springer.com/series/15056

,,

~ Springer

Published under the auspices of EPNOE*Springerbriefs in Biobased polymers covers all aspects of biobased polymer science, from the basis of this field starting from the living species in which they are synthetized (such as genetics, agronomy, plant biology) to the many applications they are used in (such as food, feed, engineering, construction, health, ... ) through to isolation and characterization, biosynthesis, biodegradation, chemical modifications, physical, chemical, mechanical and structural characterizations or biomimetic applications. All biobased polymers in all application sectors are welcome, either those produced in living species (like polysaccharides, proteins, Iignin, ... ) or those that are rebuilt by chemists as in the case of many bioplastics.

Under the editorship of Patrick Navard and a panel of experts, the series will include contributions from many of the world's most authoritative biobased polymer scientists and professionals. Readers will gain an understanding of how given biobased polymers are made and what they can be used for. They will also be able to widen their knowledge and find new opportunities due to the multidisciplinary contributions.

This series is aimed at advanced undergraduates, academic and industrial researchers and professionals studying or using biobased polymers. Each brief will bear a general introduction enabling any reader to understand its topic.

Morgan Chabannes. Eric Garcia-Diaz Laurent Clerc. Jean-Charles Benezet Frederic Becquart

Lime Hemp and Rice Husk-Based Concretes for Building Envelopes

*EPNOE The European Polysaccharide Network of Excellence (www.epnoe.eu) is a research and education network connecting academic, research institutions and companies focusing on polysaccharides and polysaccharide-related research and business.

More information about this series at http://www.springer.com/series/15056

,,

~ Springer

Morgan Chabannes LGCgE-GCE IMT Lille Douai Douai Cedex France

Jean-Charles Benezet C2MA IMT Mines Ales Ales Cedex France

and

Frederic Becquart LGCgE-GCE IMT Lille Douai Douai Cedex France

Universite de Lille Lille France Eric Garcia-Diaz C2MA IMT Mines Ales Ales Cedex France

Contents

and Universite de Lille Lille France

Laurent Clerc C2MA IMT Mines Ales Ales Cedex France

1 Introduction ..................

References ...................................

2

ISSN 2191-5415 (electronic) ISSN 2191-5407 SpringerBriefs in Molecular Science ISSN 2510-3407 ISSN 25I0-3415 (electronic) Biobased Polymers ISBN 978-3-319-67659-3 ISBN 978-3-3 I 9-67660-9 (eBook) https://doi.org/ I 0. 1007/978-3-319-67660-9

,.

Library of Congress Control Number: 2017952907

© The Author(s) 2018 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed.

The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate al the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

3

•.

l 4

Two Typical Plant Aggregates for Bio-Based Concretes . ........ .

2.1 Source and Transformation Processes ................. .

2.1.l Hemp Shiv ..........................

• ••••• •• •

5

2.1.2 Rice Husk ................

•••••-•••·· · · · ·· · · ·· 2.2 Che1nicalComposition ...................

• .. • • • • • • • · · • 2.3 Physical and Morphological Properties .................... .

2.3. l Microstructure .......................

••••••••· • 2.3.2 Densities and Porosities ......................

•••• 2.3.3 Shape and Particle Size Distribution ................ .

2.4 Specific Properties for Plant-Based Concretes ..... : ......... .

2.4.1 Water Absorption Capacity ...................... .

2.4.2 Sorption Isotherms ....................

•••••••· · · • .. • • • • • • • · · · · · · · · · · · · · · References .....................

7 8

Lime-Based Binders ..................

••. •••••· •· · · · 3.1 Production and General Properties .....................

••• 3.1.1 Calcic Lime ....................

•••••••· ••· · · · · 3.1.2 Hydraulic Lime ...................

••••••••· · · · · 3.2 Hardening Mechanisms ................

••••••••· ••· · 3.2.1 Aerial Carbonation ..........................

•••• 3.2.2 Hydraulic Setting Due to C 2 S Hydration ............

•.

3.3 Influence of Curing Conditions on Hardening ............

••.

3.3.1 Effect of Relative Humidity and Temperature ......... .

3.3.2 Effect of CO 2 Concentration ...................

••••

5 5

11 11 13

15 17 17 18 19 23 23 23

24 26 26 27

29 29 33

Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer International Publishing AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland V

Morgan Chabannes LGCgE-GCE IMT Lille Douai Douai Cedex France

Jean-Charles Benezet C2MA IMT Mines Ales Ales Cedex France

and

Frederic Becquart LGCgE-GCE IMT Lille Douai Douai Cedex France

Universite de Lille Lille France Eric Garcia-Diaz C2MA IMT Mines Ales Ales Cedex France

Contents

and Universite de Lille Lille France

Laurent Clerc C2MA IMT Mines Ales Ales Cedex France

1 Introduction ..................

References ...................................

2

ISSN 2191-5415 (electronic) ISSN 2191-5407 SpringerBriefs in Molecular Science ISSN 2510-3407 ISSN 25I0-3415 (electronic) Biobased Polymers ISBN 978-3-319-67659-3 ISBN 978-3-3 I 9-67660-9 (eBook) https://doi.org/ I 0. 1007/978-3-319-67660-9

,.

Library of Congress Control Number: 2017952907

© The Author(s) 2018 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed.

The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate al the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

3

•.

l 4

Two Typical Plant Aggregates for Bio-Based Concretes . ........ .

2.1 Source and Transformation Processes ................. .

2.1.l Hemp Shiv ..........................

• ••••• •• •

5

2.1.2 Rice Husk ................

•••••-•••·· · · · ·· · · ·· 2.2 Che1nicalComposition ...................

• .. • • • • • • • · · • 2.3 Physical and Morphological Properties .................... .

2.3. l Microstructure .......................

••••••••· • 2.3.2 Densities and Porosities ......................

•••• 2.3.3 Shape and Particle Size Distribution ................ .

2.4 Specific Properties for Plant-Based Concretes ..... : ......... .

2.4.1 Water Absorption Capacity ...................... .

2.4.2 Sorption Isotherms ....................

•••••••· · · • .. • • • • • • • · · · · · · · · · · · · · · References .....................

7 8

Lime-Based Binders ..................

••. •••••· •· · · · 3.1 Production and General Properties .....................

••• 3.1.1 Calcic Lime ....................

•••••••· ••· · · · · 3.1.2 Hydraulic Lime ...................

••••••••· · · · · 3.2 Hardening Mechanisms ................

••••••••· ••· · 3.2.1 Aerial Carbonation ..........................

•••• 3.2.2 Hydraulic Setting Due to C 2 S Hydration ............

•.

3.3 Influence of Curing Conditions on Hardening ............

••.

3.3.1 Effect of Relative Humidity and Temperature ......... .

3.3.2 Effect of CO 2 Concentration ...................

••••

5 5

11 11 13

15 17 17 18 19 23 23 23

24 26 26 27

29 29 33

Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer International Publishing AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland V

VI

Contents

3.4

Physico-Mechanical Properties After Hardening . . . . . . . . . . . . . .

3.4. I Porosity and Hygrothermal Properties . . . . . . . . . . . . . . . .

3.4.2 Mechanical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . .

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

5

Lime and Hemp or Rice Husk Concretes for the Building Envelope: Applications and General Properties ............... .

4.1 Applications in Buildings, Casting Processes and Mix Design of Plant-Based Concretes ............................... .

4.1.l Application of Hemp Concrete in Housing ........... .

4.1.2 Mix Design of Bio-Based Concretes ................ .

4.2 Measuring Thermal and Mechanical Properties .............. .

4.2.l Thermal Conductivity .......................... .

4.2.2 Mechanical Properties Under Uniaxial Compression .... .

4.2.3 Shear Strength ................................ .

4.3 From Design to Specific Properties of Bio-Based Concretes .... .

4.3.l Porosity and Thermal Conductivity ................. .

4.3.2 Mechanical Properties .......................... .

4.4 Effect of Curing Conditions on Hardening and Mechanical Properties of Plant-Based Concretes ...................... .

4.4. l Curing Conditions ............................. .

4.4.2 Mechanical Performances ........................ .

4.4.3 Binder Hardening ............................. .

4.4.4 Conclusion About Curing Regime and Mechanical Performances of Plant-Based Concretes .............. .

4.5 Studying the Shear Behavior of Plant-Based Concretes ........ .

4.5.l Interest of the Analysis of the Mechanical Behavior of Plant-Based Concretes Under Shear Loading .......... . ,. 4.5.2 Experimental Results for Triaxial Compression on LHC and LRC .................................... .

4.5.3 First Conclusions Regarding the Triaxial Compression of Plant-Based Concretes .......................... .

References ............................................ .

Conclusion and Outlooks ................................

References ............................................

Reproduction of figures-Reference

list. .........................

34 34 34 40

Nomenclature

45 45 45 46 55 55 58 59 61 61

66

LHC LRC Ps

PA PT

71 71

1lo

76 79

11T

88 89 89

90 95 95

. 99 . l01 . l03

111

C, S, H, A

SEM BSE-SEM TGA

XRD A, Band W BIA W/B Wr WM

ISC

oc ACC MC TA CS Ee 11JP 11TOT

"-r "-o

MT

Lime and hemp concrete Lime and Rice husk concrete Bulk density of plant aggregates Apparent density of a particle True density of the solid phase Open porosity in the particle Intergranular porosity in bulk aggregates Total porosity in bulk aggregates . .

CaO, SiO 2 , H2 O, Al 2 O 3 (cement chemist notation) Scanning electron microscopy Back-scattered scanning electron microscopy Thennogravimetric analysis X-ray diffraction Aggregate, binder and water contents Binder-on-aggregates mass ratio Water-on-binder mass ratio Prewetting water Mixing water Indoor standard conditions Outdoor exposure conditions Accelerating carbonation curing Moist curing Thermal activation Compressive strength Tangent modulus on the loading cycle Intergranular porosity within the hardened concrete Total porosity within the hardened concrete . .

Thermal conductivity (flow parallel to compaction axis) Thermal conductivity (flow orthogonal to compaction axis) Manual tamping

vii

1 •· HIH""'f HIHHHIHHHIH HIii 11111

'''''""'.

VI

Contents

3.4

Physico-Mechanical Properties After Hardening . . . . . . . . . . . . . .

3.4. I Porosity and Hygrothermal Properties . . . . . . . . . . . . . . . .

3.4.2 Mechanical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . .

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

5

Lime and Hemp or Rice Husk Concretes for the Building Envelope: Applications and General Properties ............... .

4.1 Applications in Buildings, Casting Processes and Mix Design of Plant-Based Concretes ............................... .

4.1.l Application of Hemp Concrete in Housing ........... .

4.1.2 Mix Design of Bio-Based Concretes ................ .

4.2 Measuring Thermal and Mechanical Properties .............. .

4.2.l Thermal Conductivity .......................... .

4.2.2 Mechanical Properties Under Uniaxial Compression .... .

4.2.3 Shear Strength ................................ .

4.3 From Design to Specific Properties of Bio-Based Concretes .... .

4.3.l Porosity and Thermal Conductivity ................. .

4.3.2 Mechanical Properties .......................... .

4.4 Effect of Curing Conditions on Hardening and Mechanical Properties of Plant-Based Concretes ...................... .

4.4. l Curing Conditions ............................. .

4.4.2 Mechanical Performances ........................ .

4.4.3 Binder Hardening ............................. .

4.4.4 Conclusion About Curing Regime and Mechanical Performances of Plant-Based Concretes .............. .

4.5 Studying the Shear Behavior of Plant-Based Concretes ........ .

4.5.l Interest of the Analysis of the Mechanical Behavior of Plant-Based Concretes Under Shear Loading .......... . ,. 4.5.2 Experimental Results for Triaxial Compression on LHC and LRC .................................... .

4.5.3 First Conclusions Regarding the Triaxial Compression of Plant-Based Concretes .......................... .

References ............................................ .

Conclusion and Outlooks ................................

References ............................................

Reproduction of figures-Reference

list. .........................

34 34 34 40

Nomenclature

45 45 45 46 55 55 58 59 61 61

66

LHC LRC Ps

PA PT

71 71

1lo

76 79

11T

88 89 89

90 95 95

. 99 . l01 . l03

111

C, S, H, A

SEM BSE-SEM TGA

XRD A, Band W BIA W/B Wr WM

ISC

oc ACC MC TA CS Ee 11JP 11TOT

"-r "-o

MT

Lime and hemp concrete Lime and Rice husk concrete Bulk density of plant aggregates Apparent density of a particle True density of the solid phase Open porosity in the particle Intergranular porosity in bulk aggregates Total porosity in bulk aggregates . .

CaO, SiO 2 , H2 O, Al 2 O 3 (cement chemist notation) Scanning electron microscopy Back-scattered scanning electron microscopy Thennogravimetric analysis X-ray diffraction Aggregate, binder and water contents Binder-on-aggregates mass ratio Water-on-binder mass ratio Prewetting water Mixing water Indoor standard conditions Outdoor exposure conditions Accelerating carbonation curing Moist curing Thermal activation Compressive strength Tangent modulus on the loading cycle Intergranular porosity within the hardened concrete Total porosity within the hardened concrete . .

Thermal conductivity (flow parallel to compaction axis) Thermal conductivity (flow orthogonal to compaction axis) Manual tamping

vii

1 •· HIH""'f HIHHHIHHHIH HIii 11111

'''''""'.

viii

vc ROC d,m ITZ p~ q

cr:n M' (j)p

C

FM

Nomenclature

Vi bro-compaction Rate of carbonation Days, months Interfacial transition zone Initial effective confining pressure Deviatoric stress Mean effective pressure Stress ratio Peak friction angle Cohesion Failure mode

Chapter 1

Introduction

According to the International Energy Agency (IEA), the building sector accounts for one-third of final energy consumption and global carbon emissions in the world [l]. In Europe, most countries adopted their own thermal regulations after the first oil crisis in the 1970s in order to limit heat loss in buildings. In an effort to reduce energy consumption for the heating, some buildings were sealed too tightly without adequate ventilation, leading to poor indoor air quality. Furthermore, the thermal comfort in summer has been gradually considered through the different amendments of thermal regulations but it was largely ignored until the 1990s. The energy demand for air conditioning has increased in southern countries but not exclusively.

It also applies to countries with a cold climate. Overheating in summer or even in the mid-season is frequently noted in Germany or Nordic countries where buildings are designed with high levels of thermal insulation, low permeability and solar heat gain through the glazing. Air conditioning has become relatively common in tertiary buildings even though it strongly affects the climate [2]. Within the framework of the Kyoto protocol, the European Union (EU) adopted a directive for the energy efficiency of buildings (Energy Performance of Building Directive known as EPBD) in 2002. It was revised in 2010 in order to provide harmonized methods for calculating the energy performance of buildings in thennal regulations, taking greater account of heating and cooling installations [3]. The French Thermal Regulation has been developed and strengthened several times. In 2012, the aim of the latest version was to achieve a decrease of 38% in the energy consumption of residential and tertiary buildings by 2020 compared to 2008 and a fourfold reduction of greenhouse gas emissions by 2050 in comparison to the level of emissions in 1990 [4]. Half of the building stock was built before 1970 and thus without any thermal insulation. Furthermore, over the following decades, heat insulation systems and design methods were not necessarily appropriate as briefly mentioned above (overheating, tight houses without efficient ventilation, lack of breathability, wall condensation, excessive use of air conditioning). Due to the low

© The Author(s) 2018 M. Chabannes et al., Lime Hemp and Rice Husk-Based Concretes for Building Envelopes, Biobased Polymers, https://doi.org/10.1007/978-3-319-67660-9_1

"'"""'"'"""""""'"''

,.,,,,,,,,1111111111111,.

viii

vc ROC d,m ITZ p~ q

cr:n M' (j)p

C

FM

Nomenclature

Vi bro-compaction Rate of carbonation Days, months Interfacial transition zone Initial effective confining pressure Deviatoric stress Mean effective pressure Stress ratio Peak friction angle Cohesion Failure mode

Chapter 1

Introduction

According to the International Energy Agency (IEA), the building sector accounts for one-third of final energy consumption and global carbon emissions in the world [l]. In Europe, most countries adopted their own thermal regulations after the first oil crisis in the 1970s in order to limit heat loss in buildings. In an effort to reduce energy consumption for the heating, some buildings were sealed too tightly without adequate ventilation, leading to poor indoor air quality. Furthermore, the thermal comfort in summer has been gradually considered through the different amendments of thermal regulations but it was largely ignored until the 1990s. The energy demand for air conditioning has increased in southern countries but not exclusively.

It also applies to countries with a cold climate. Overheating in summer or even in the mid-season is frequently noted in Germany or Nordic countries where buildings are designed with high levels of thermal insulation, low permeability and solar heat gain through the glazing. Air conditioning has become relatively common in tertiary buildings even though it strongly affects the climate [2]. Within the framework of the Kyoto protocol, the European Union (EU) adopted a directive for the energy efficiency of buildings (Energy Performance of Building Directive known as EPBD) in 2002. It was revised in 2010 in order to provide harmonized methods for calculating the energy performance of buildings in thennal regulations, taking greater account of heating and cooling installations [3]. The French Thermal Regulation has been developed and strengthened several times. In 2012, the aim of the latest version was to achieve a decrease of 38% in the energy consumption of residential and tertiary buildings by 2020 compared to 2008 and a fourfold reduction of greenhouse gas emissions by 2050 in comparison to the level of emissions in 1990 [4]. Half of the building stock was built before 1970 and thus without any thermal insulation. Furthermore, over the following decades, heat insulation systems and design methods were not necessarily appropriate as briefly mentioned above (overheating, tight houses without efficient ventilation, lack of breathability, wall condensation, excessive use of air conditioning). Due to the low

© The Author(s) 2018 M. Chabannes et al., Lime Hemp and Rice Husk-Based Concretes for Building Envelopes, Biobased Polymers, https://doi.org/10.1007/978-3-319-67660-9_1

"'"""'"'"""""""'"''

,.,,,,,,,,1111111111111,.

2

Introduction

renewal rate of the building stock, the energy retrofit of existing buildings is absolutely fundamental to achieve the targets in terms of environmental impact. The construction industry is able to provide a significant potential for the reduction of ~reenhouse gas emissi~ns. The energy efficiency of buildings during their operational phase tends to improve over time as a result of increasingly advanced insulating materials. Nevertheless, it is essential to pay close attention to the carbon footprint of selected materials. The environmental impact of building materials is not taken into account in European and French standards even though the embodied energy of materials is a key factor of the whole life cycle of buildings (Life Cycle Analysis approach). Conventional construction systems used for residential buildings mostly combine an insulating layer with a load bearing structure (concrete blocks). Mineral wools and polystyrene cover almost the whole market of insulating materials despite their high carbon footprint [5]. In order to keep buildings free from the risk of water condensation in traditional envelopes using mineral wools and plasterboard, self-insulating blocks like autoclaved aerated concrete or lightweight clay bricks have expanded in recent years. These load-bearing blocks have attractive hygrothermal properties [6] but they use non-renewable resources and their carbon footprint remains high (especially that of fired-clay bricks) [5]. The last two decades have witnessed the emergence of bio-based building materials mixing plant-derived aggregates with mineral binders. This return to old building methods is arousing great interest. In this field, hemp concrete has been well researched. It is designed by mixing hemp shives (the woody part of hemp stems) with lime or other binders. Crop residues are renewable resources and their use does not haim the environment. The carbon footp1int of hemp-based concretes was found to be negative due to carbon sequestration during hemp growth and lime carbonation during the hardening of the concrete [5, 7]. Hemp concretes are manufactured with a high volume fraction of shives providing an important porosity to .t~e hardened material. As a result, they show low thermal conductivity and good ab1h.ty to buffer temperature and humidity variations. Hemp concrete prevents condensation, allows buildings to breathe (air-tight but water permeable). Thus, this bio-based concrete reduces heating and air conditioning needs while ensuring good indoor thermal comfort [8-10].

It is obvious that the diversification of renewable and easily available plant resources promotes and develops biomass-based construction contributing to carbon storage and sequestration. Rice is the first cereal in the world for human food. It is locally grown in the South of France. The outer covering of rice grains (called rice husk) is often considered as a waste material. This crop residue causes critical problems in rice growing areas given that high volumes are generated and not used in. a .beneficial. way. !he re~overy of whole rice husk without any burning or gnndmg to design a hghtwe1ght insulating bio-based concrete was almost unexplored before. The new plant aggregate is mixed with lime-based binders and macroscopic properties of the innovative rice husk concrete are compared with those of hemp concrete.

Introduction

3

Only the lime-based binders will be considered in the book. Thei~·. carbon footprint is much more favorable than that of Portland cement [11]. In add.1t1on,the water-vapor permeability, the low density (especially that of hydrated lune), the hardening through carbonation and the ductile behavior of lime binders are considerable assets for the mixing with hygroscopic and deformable plant aggregates.

Mechanical properties of hemp concretes depend on many factors such. as casting process, binder content, type and size distribution of .agg.reg~tes, cunng conditions and age. In most cases, hemp concrete for a wall application 1s manua~ly tamped into a wooden framework (cast on the buildi~g site) .and. the on-site implementation is conducted in accordance with professional gu1del111es[12]. In this case, the mechanical performances of the plant-based concrete are very low.

The main weakness of hemp concretes using lime as binder is the long time they require to cure when cast on-site. However, the hardening th1~oughthe .carbonation process is known to provide additional strength to the matenal over t1~e [13]. I.n addition, very little prior research has been done about the effect of cunng. conditions (relative humidity, temperature or even CO 2 content) on binder hardenmg and strength development of plant-based concretes. Using precast bl_ocks is another option for the construction of walls with plant-based concretes. This .method ~~ens up interesting ways of improving the early age strength. Optimal cunng con~1t1ons in order to accelerate the hardening of plant-based concretes should be subject to research as part of precast industry. In addition, some authors [14-16] ~tudied_the effect of high compaction of freshly-mixed hemp concrete under static loadmg.

After hardening, hemp concrete shows significant increase in compressive strength and ductility. Whether they are cast in situ or in the form of precast blocks, plant-based concretes are only considered as insulating mate1ials. The structural design practice of wood frame walls associated with hemp. concrete d?es not assume any contribution of the plant-based material whereas 1t may contnb.ute to the racking strength of walls. More knowledge about the shear behav1or of plant-based concrete is needed to optimize th~. structur_al ~esign. One. can also identify insufficient hindsight towards the durability of this kmd of matenal. Some authors began to turn their attention to this research focus [17].

The book provides a three-step outline: • The first part proceeds with physical and chemical characterization of plant-derived aggregates (hemp shiv and rice husk~. .. .

• The second part mainly deals with the effect of curmg conditions on hardenmg mechanisms and strength development of lime-based binders.

• The last and most significant chapter addresses mix design and hardened-state properties (porosities, the1mal conductivity, compressive strengt_h and even shear strength) of hemp and rice husk-based concretes. A large part 1s devoted to the influence of curing conditions on the strength development of manually tamped plant-based concretes. In addition, the results from triaxial compression of vibro-compacted plant-based concretes are presented.

2

Introduction

renewal rate of the building stock, the energy retrofit of existing buildings is absolutely fundamental to achieve the targets in terms of environmental impact. The construction industry is able to provide a significant potential for the reduction of ~reenhouse gas emissi~ns. The energy efficiency of buildings during their operational phase tends to improve over time as a result of increasingly advanced insulating materials. Nevertheless, it is essential to pay close attention to the carbon footprint of selected materials. The environmental impact of building materials is not taken into account in European and French standards even though the embodied energy of materials is a key factor of the whole life cycle of buildings (Life Cycle Analysis approach). Conventional construction systems used for residential buildings mostly combine an insulating layer with a load bearing structure (concrete blocks). Mineral wools and polystyrene cover almost the whole market of insulating materials despite their high carbon footprint [5]. In order to keep buildings free from the risk of water condensation in traditional envelopes using mineral wools and plasterboard, self-insulating blocks like autoclaved aerated concrete or lightweight clay bricks have expanded in recent years. These load-bearing blocks have attractive hygrothermal properties [6] but they use non-renewable resources and their carbon footprint remains high (especially that of fired-clay bricks) [5]. The last two decades have witnessed the emergence of bio-based building materials mixing plant-derived aggregates with mineral binders. This return to old building methods is arousing great interest. In this field, hemp concrete has been well researched. It is designed by mixing hemp shives (the woody part of hemp stems) with lime or other binders. Crop residues are renewable resources and their use does not haim the environment. The carbon footp1int of hemp-based concretes was found to be negative due to carbon sequestration during hemp growth and lime carbonation during the hardening of the concrete [5, 7]. Hemp concretes are manufactured with a high volume fraction of shives providing an important porosity to .t~e hardened material. As a result, they show low thermal conductivity and good ab1h.ty to buffer temperature and humidity variations. Hemp concrete prevents condensation, allows buildings to breathe (air-tight but water permeable). Thus, this bio-based concrete reduces heating and air conditioning needs while ensuring good indoor thermal comfort [8-10].

It is obvious that the diversification of renewable and easily available plant resources promotes and develops biomass-based construction contributing to carbon storage and sequestration. Rice is the first cereal in the world for human food. It is locally grown in the South of France. The outer covering of rice grains (called rice husk) is often considered as a waste material. This crop residue causes critical problems in rice growing areas given that high volumes are generated and not used in. a .beneficial. way. !he re~overy of whole rice husk without any burning or gnndmg to design a hghtwe1ght insulating bio-based concrete was almost unexplored before. The new plant aggregate is mixed with lime-based binders and macroscopic properties of the innovative rice husk concrete are compared with those of hemp concrete.

Introduction

3

Only the lime-based binders will be considered in the book. Thei~·. carbon footprint is much more favorable than that of Portland cement [11]. In add.1t1on,the water-vapor permeability, the low density (especially that of hydrated lune), the hardening through carbonation and the ductile behavior of lime binders are considerable assets for the mixing with hygroscopic and deformable plant aggregates.

Mechanical properties of hemp concretes depend on many factors such. as casting process, binder content, type and size distribution of .agg.reg~tes, cunng conditions and age. In most cases, hemp concrete for a wall application 1s manua~ly tamped into a wooden framework (cast on the buildi~g site) .and. the on-site implementation is conducted in accordance with professional gu1del111es[12]. In this case, the mechanical performances of the plant-based concrete are very low.

The main weakness of hemp concretes using lime as binder is the long time they require to cure when cast on-site. However, the hardening th1~oughthe .carbonation process is known to provide additional strength to the matenal over t1~e [13]. I.n addition, very little prior research has been done about the effect of cunng. conditions (relative humidity, temperature or even CO 2 content) on binder hardenmg and strength development of plant-based concretes. Using precast bl_ocks is another option for the construction of walls with plant-based concretes. This .method ~~ens up interesting ways of improving the early age strength. Optimal cunng con~1t1ons in order to accelerate the hardening of plant-based concretes should be subject to research as part of precast industry. In addition, some authors [14-16] ~tudied_the effect of high compaction of freshly-mixed hemp concrete under static loadmg.

After hardening, hemp concrete shows significant increase in compressive strength and ductility. Whether they are cast in situ or in the form of precast blocks, plant-based concretes are only considered as insulating mate1ials. The structural design practice of wood frame walls associated with hemp. concrete d?es not assume any contribution of the plant-based material whereas 1t may contnb.ute to the racking strength of walls. More knowledge about the shear behav1or of plant-based concrete is needed to optimize th~. structur_al ~esign. One. can also identify insufficient hindsight towards the durability of this kmd of matenal. Some authors began to turn their attention to this research focus [17].

The book provides a three-step outline: • The first part proceeds with physical and chemical characterization of plant-derived aggregates (hemp shiv and rice husk~. .. .

• The second part mainly deals with the effect of curmg conditions on hardenmg mechanisms and strength development of lime-based binders.

• The last and most significant chapter addresses mix design and hardened-state properties (porosities, the1mal conductivity, compressive strengt_h and even shear strength) of hemp and rice husk-based concretes. A large part 1s devoted to the influence of curing conditions on the strength development of manually tamped plant-based concretes. In addition, the results from triaxial compression of vibro-compacted plant-based concretes are presented.

4

Introduction

References

Chapter 2 W

I. IEA, Transilion Su~·/ainable Buildings: Strategies and Opportunities to 2050 (IEA, 2013) 2. U. (UBA), Budding air cond1t1ornng in Germany 2015. Available: http://www.umweltbunde samt.de/en/top1cs/ec~nom1cs-consumption/products/fluorinated-greenhouse-gases-fully-halo genated-cfcs/appl 1cat1on-domams-emission-reduction/bu iId ing-air-condition ing. Accessed: oI Jan 2017

Two Typical Plant Aggregates for Bio-Based Concretes

3. European Parliament, Directive 20 I 0/31/EU on the Energy Performance of Buildings 20 I o.

Ava1lab_le:http://ec.europa.eu/energy/en/topics/energy-efficiency/buildings 4. S. Amz1ane, L: Arnaud, Les betons de granulats d'origine vege1ale Application au be/On de chanvre (Lavo1s1er., France, 2013) 5. M.P. Boutin, C. Flamin, S. Quinton, G. Gosse, Analyse du cycle de vie d'un mur en beton de chanvre banche sur ossature bois (2005) 6. A. Evrard, Transient hygrothermal behaviour of Lime-Hemp . . .

C at h o I.1c (Urnvers1ty of Louvam, Belgium, 2008), p. 140

M·ite .·. , 1·1·als, , Pli .D . TI1es1s,

7. ~.'. ~.rrigoni, R: P:losato,. P. Meli,1_, G. Ruggieri, S. Sabbadini, G. Dotelli, Life cycle build mg. materials: The role of carbonation, mixture components and assessment of n<1tm<1I transpo1t m the environmental impacts of hempcrete blocks. J. Clean. Prod. 149 1051-1061 (2017) ' 8. F. C_ollet, S. Pretot, Thermal conductivity of hemp concretes: variation with formulation density and water content. Constr. Build. Mater. 65, 612-619 (2014) ' 9. F. Collet, 1. Chamoin, S. Pretot, C. Lanos, Comparison of the hygric behaviour of three hemp concretes. Energy Build. 62, 294-303 (2013) I 0. A.-D. Tran Le,_ ~tude des transfeits hygrothermiques dans le beton de chanvre et leur apphcat1on au bat1ment, PhD Thesis, (Reims Champagne-Ardennes University France 2010) ' ' p. 209 11. M. Chabannes, Formulation et ~tude des proprietes mecaniques d'agrobetons legers isolants a base de balles de nz et de chenevotte pour l'eco-construction, (University of Montpellier France, 2015), p. 215 · ' 12. c,-~n -~hanvre, ~onsluire en Chanvre. Regles professionn.elles d'execution, (SEBTP. Societe cl Ed1t1on du Bat1ment et des Travaux Publics, 2012) 13. L. Arnaud, E. Gourlay, Experimental study of parameters influencing mechanical properties of hemp concretes. Constr. Build. Mater. 28(1), 50-56 (2012) 14. ,J'.T. Nguyen.' Contrib,ution a l'etude de la formulation et du procede de fabrication d'elements de construction en beton de chanvre, PhD thesis, (Bretagne-Sud University France 20 I 0) ~,~

'

'

Hemp shiv (well-known) and rice husk (novel) Many by-products of plant origin have been incorporated in mineral binders.

However, it is important to distinguish plant fibers used as reinforcement in cement composite materials from plant-derived aggregates used for the manufacturing of lightweight insulating concretes (bio-based concretes). Those can be defined as the association of a high volume fraction of crop residues with a mineral binder [l].

This book does not deal with load-bearing concretes with very small amounts of aggregates or reinforcing fibers.

Most of the plant aggregates are derived from stems (hemp, flax, sunflower), straws (sorghum or miscanthus) and trunks (woodchips).

After grinding, the woody part of hemp stems gives rise to hemp shiv, a wellknown aggregate associated with a lime-based binder to design Lime and Hemp Concrete (LHC). In order to diversify crop by-products, a novel kind of aggregate is explored. It corresponds to rice husk, the protective shell of rice grains. Since rice husk particles come from a totally different part of the plant, their characteristics will be presented and compared· to those of hemp shives.

15. P. Trone_t, T. Lecompte, V. Picandet, C. Baley, Study of lime hemp composite precasting by compaction of fresh mix-an mstrumented die to measure friction and stress state. Powder Technol. 258, 285-296 (2014) 16. P. ~ronet, T. Lecompte, des1g.n'.c~stmg pr~cess 17. S. _Maice<1u,P. Gle, M. Influence of accelerated 524-530 (2016)

V. Picandet, C. Baylet, Study of lime and hemp concrete (lhc)-mix and, mech,mical behaviors. Cem. Coner. Compos. 67, 60-72 (2016) Gueguen-mmerbe, E. Gourlay, S. Moscardelli, I. Nour, s. Amziane, agmg on the prope1ties of hemp concretes. Constr. Build. M· t . 139 a e1. ,

2.1 2.1.1

Source and Transformation Processes Hemp Shiv

Hemp (Cannabis Sativa) is an annual plant whose height is from 1-3 m (Fig. 2.la).

This species is dedicated to the cultivation of industrial hemp in Central Asia and Europe. Hemp is grown as a break crop and harvested after 4 months of maturity [2, 3]. Thereafter, stems are cut and left on the field for a few weeks (retting). When the moisture content of stems is around 15%, those are harvested and taken to the defibering process to separate the woody part from the fibers (Fig. 2.lb). © The Author(s) 2018 M. Chabannes et al., Lime Hemp and Rice Husk-Based Concretes for Building Envelopes, Biobased Polymers, https://doi.org/ 10.1007/978-3-319-67660-9_2

5

4

Introduction

References

Chapter 2 W

I. IEA, Transilion Su~·/ainable Buildings: Strategies and Opportunities to 2050 (IEA, 2013) 2. U. (UBA), Budding air cond1t1ornng in Germany 2015. Available: http://www.umweltbunde samt.de/en/top1cs/ec~nom1cs-consumption/products/fluorinated-greenhouse-gases-fully-halo genated-cfcs/appl 1cat1on-domams-emission-reduction/bu iId ing-air-condition ing. Accessed: oI Jan 2017

Two Typical Plant Aggregates for Bio-Based Concretes

3. European Parliament, Directive 20 I 0/31/EU on the Energy Performance of Buildings 20 I o.

Ava1lab_le:http://ec.europa.eu/energy/en/topics/energy-efficiency/buildings 4. S. Amz1ane, L: Arnaud, Les betons de granulats d'origine vege1ale Application au be/On de chanvre (Lavo1s1er., France, 2013) 5. M.P. Boutin, C. Flamin, S. Quinton, G. Gosse, Analyse du cycle de vie d'un mur en beton de chanvre banche sur ossature bois (2005) 6. A. Evrard, Transient hygrothermal behaviour of Lime-Hemp . . .

C at h o I.1c (Urnvers1ty of Louvam, Belgium, 2008), p. 140

M·ite .·. , 1·1·als, , Pli .D . TI1es1s,

7. ~.'. ~.rrigoni, R: P:losato,. P. Meli,1_, G. Ruggieri, S. Sabbadini, G. Dotelli, Life cycle build mg. materials: The role of carbonation, mixture components and assessment of n<1tm<1I transpo1t m the environmental impacts of hempcrete blocks. J. Clean. Prod. 149 1051-1061 (2017) ' 8. F. C_ollet, S. Pretot, Thermal conductivity of hemp concretes: variation with formulation density and water content. Constr. Build. Mater. 65, 612-619 (2014) ' 9. F. Collet, 1. Chamoin, S. Pretot, C. Lanos, Comparison of the hygric behaviour of three hemp concretes. Energy Build. 62, 294-303 (2013) I 0. A.-D. Tran Le,_ ~tude des transfeits hygrothermiques dans le beton de chanvre et leur apphcat1on au bat1ment, PhD Thesis, (Reims Champagne-Ardennes University France 2010) ' ' p. 209 11. M. Chabannes, Formulation et ~tude des proprietes mecaniques d'agrobetons legers isolants a base de balles de nz et de chenevotte pour l'eco-construction, (University of Montpellier France, 2015), p. 215 · ' 12. c,-~n -~hanvre, ~onsluire en Chanvre. Regles professionn.elles d'execution, (SEBTP. Societe cl Ed1t1on du Bat1ment et des Travaux Publics, 2012) 13. L. Arnaud, E. Gourlay, Experimental study of parameters influencing mechanical properties of hemp concretes. Constr. Build. Mater. 28(1), 50-56 (2012) 14. ,J'.T. Nguyen.' Contrib,ution a l'etude de la formulation et du procede de fabrication d'elements de construction en beton de chanvre, PhD thesis, (Bretagne-Sud University France 20 I 0) ~,~

'

'

Hemp shiv (well-known) and rice husk (novel) Many by-products of plant origin have been incorporated in mineral binders.

However, it is important to distinguish plant fibers used as reinforcement in cement composite materials from plant-derived aggregates used for the manufacturing of lightweight insulating concretes (bio-based concretes). Those can be defined as the association of a high volume fraction of crop residues with a mineral binder [l].

This book does not deal with load-bearing concretes with very small amounts of aggregates or reinforcing fibers.

Most of the plant aggregates are derived from stems (hemp, flax, sunflower), straws (sorghum or miscanthus) and trunks (woodchips).

After grinding, the woody part of hemp stems gives rise to hemp shiv, a wellknown aggregate associated with a lime-based binder to design Lime and Hemp Concrete (LHC). In order to diversify crop by-products, a novel kind of aggregate is explored. It corresponds to rice husk, the protective shell of rice grains. Since rice husk particles come from a totally different part of the plant, their characteristics will be presented and compared· to those of hemp shives.

15. P. Trone_t, T. Lecompte, V. Picandet, C. Baley, Study of lime hemp composite precasting by compaction of fresh mix-an mstrumented die to measure friction and stress state. Powder Technol. 258, 285-296 (2014) 16. P. ~ronet, T. Lecompte, des1g.n'.c~stmg pr~cess 17. S. _Maice<1u,P. Gle, M. Influence of accelerated 524-530 (2016)

V. Picandet, C. Baylet, Study of lime and hemp concrete (lhc)-mix and, mech,mical behaviors. Cem. Coner. Compos. 67, 60-72 (2016) Gueguen-mmerbe, E. Gourlay, S. Moscardelli, I. Nour, s. Amziane, agmg on the prope1ties of hemp concretes. Constr. Build. M· t . 139 a e1. ,

2.1 2.1.1

Source and Transformation Processes Hemp Shiv

Hemp (Cannabis Sativa) is an annual plant whose height is from 1-3 m (Fig. 2.la).

This species is dedicated to the cultivation of industrial hemp in Central Asia and Europe. Hemp is grown as a break crop and harvested after 4 months of maturity [2, 3]. Thereafter, stems are cut and left on the field for a few weeks (retting). When the moisture content of stems is around 15%, those are harvested and taken to the defibering process to separate the woody part from the fibers (Fig. 2.lb). © The Author(s) 2018 M. Chabannes et al., Lime Hemp and Rice Husk-Based Concretes for Building Envelopes, Biobased Polymers, https://doi.org/ 10.1007/978-3-319-67660-9_2

5

98

4

Lime and Hemp or Rice Husk Concretes for the Building ...

52. M. Albayrak, A. Yoriikoglu S Karahan S Atl"h · 1 an, H. Yilmaz ' ·. ' · Arunta~, I. Girgin, Influence of _ rt . dd" .

3 I 6~e::3;~5 '~2~;;; on prope1t1es of autoclaved aerated concrete. Build. Environ. 42(9),

Chapter 5

53

Conclusion and Outlooks

- M. Jerman, M. Keppeit, J. Vyborny, R. Cerny, Hygric, thermal and durabilit r ·· autoclaved aerated concrete. Constr. Build. Mater. 41, 352-359 (2013) y p ope1t1es of

54

Ai~bomiCan,M. Fan, Development - E._P_w<1step<1pe1. onstr. Build. Mater. 40, 55 - 1. Wu, G. Bai, H. Zhao, X. Li, 1 ;t;~;~e;~-~~~ hollow block as

;~?

of Wood-Crete building materials from sawdust and 361-366 (2013) Mechanical and thermal tests of • · · selt~insulation wall materials. Constr. a;u/1~no;;;~:; 1~

56. M. Sutcu, J.J. _Del Coz Diaz, F.P. Alvarez Rabanal, o. Gencel, s. Akkui . . pe1formance opt1m1zat1onof hollow clay bricks made up of . . . . E t, The1m<1l 96-108 (20l 4 ) pape1 waste, nergy Build. 75, 57. ~---\ ShTibhib, H.SI.Qatta, M.S. Hamza, Enhancement in thermal and mechanical prope1ties of IIC s. erm. Cl. 17(4), 1119-1123 (2013)

The results reported in this document first contribute to the development of an innovative plant-based concrete using raw rice husk. This crop residue is available throughout the year at low cost and its use to manufacture bio-based concretes for green building provides a new recovery sector for a local by-product coming from rice farming in France.

The different origin of rice husk compared to plant particles coming from stalks (hemp shives, sunflower aggregates, etc.) means that physical (density, water absorption) and morphological properties of rice husk are very different.

Hemp shiv and rice husk were mixed with lime-based binders and two different casting processes were used. The first one corresponds to manual tamping as done by workers on the building site and the second one is based on vibro-compaction of the freshly-mixed plant-based material. For a given binder-to-aggregate mass ratio and manual tamping, it is almost impossible to reach a same apparent density for hemp and rice-husk based concretes owing to the apparent density of rice husk which is more than twice that of hemp shiv. With the vibro-compaction process, it was possible to achieve a close density for plant-based concretes by increasing the density of hemp concrete through the reduction of the macroscopic inter-particles porosity.

The inter-particles porosity of lime and rice husk concrete is considerably higher than that of hemp-lime concrete. This high amount of voids is such that the rice-husk based concrete can compete with hemp concrete in tenns of thermal conductivity. However, the adverse effect of this granular stacking partly explains the lower mechanical performances of the concrete using rice husk as aggregate, irrespective of curing conditions.

Plant-based concretes cast by manual tamping have shown a same hardening kinetics of the lime binder over 10 months under natural carbonation (20 °C, 50% RH or outdoor exposure) while the strength development of rice husk concrete over time was strongly limited compared to that of hemp concrete. This was attributed to the weaker bond strength of the binder with rice husk. © The Author(s) 2018 M. Chabannes et al., Lime Hemp and Rice Husk-Based Concretes for Building Envelopes, Biobased Polymers, https://doi.org/ I 0.1007 /978-3-319-67660-9 _5

99

98

4

Lime and Hemp or Rice Husk Concretes for the Building ...

52. M. Albayrak, A. Yoriikoglu S Karahan S Atl"h · 1 an, H. Yilmaz ' ·. ' · Arunta~, I. Girgin, Influence of _ rt . dd" .

3 I 6~e::3;~5 '~2~;;; on prope1t1es of autoclaved aerated concrete. Build. Environ. 42(9),

Chapter 5

53

Conclusion and Outlooks

- M. Jerman, M. Keppeit, J. Vyborny, R. Cerny, Hygric, thermal and durabilit r ·· autoclaved aerated concrete. Constr. Build. Mater. 41, 352-359 (2013) y p ope1t1es of

54

Ai~bomiCan,M. Fan, Development - E._P_w<1step<1pe1. onstr. Build. Mater. 40, 55 - 1. Wu, G. Bai, H. Zhao, X. Li, 1 ;t;~;~e;~-~~~ hollow block as

;~?

of Wood-Crete building materials from sawdust and 361-366 (2013) Mechanical and thermal tests of • · · selt~insulation wall materials. Constr. a;u/1~no;;;~:; 1~

56. M. Sutcu, J.J. _Del Coz Diaz, F.P. Alvarez Rabanal, o. Gencel, s. Akkui . . pe1formance opt1m1zat1onof hollow clay bricks made up of . . . . E t, The1m<1l 96-108 (20l 4 ) pape1 waste, nergy Build. 75, 57. ~---\ ShTibhib, H.SI.Qatta, M.S. Hamza, Enhancement in thermal and mechanical prope1ties of IIC s. erm. Cl. 17(4), 1119-1123 (2013)

The results reported in this document first contribute to the development of an innovative plant-based concrete using raw rice husk. This crop residue is available throughout the year at low cost and its use to manufacture bio-based concretes for green building provides a new recovery sector for a local by-product coming from rice farming in France.

The different origin of rice husk compared to plant particles coming from stalks (hemp shives, sunflower aggregates, etc.) means that physical (density, water absorption) and morphological properties of rice husk are very different.

Hemp shiv and rice husk were mixed with lime-based binders and two different casting processes were used. The first one corresponds to manual tamping as done by workers on the building site and the second one is based on vibro-compaction of the freshly-mixed plant-based material. For a given binder-to-aggregate mass ratio and manual tamping, it is almost impossible to reach a same apparent density for hemp and rice-husk based concretes owing to the apparent density of rice husk which is more than twice that of hemp shiv. With the vibro-compaction process, it was possible to achieve a close density for plant-based concretes by increasing the density of hemp concrete through the reduction of the macroscopic inter-particles porosity.

The inter-particles porosity of lime and rice husk concrete is considerably higher than that of hemp-lime concrete. This high amount of voids is such that the rice-husk based concrete can compete with hemp concrete in tenns of thermal conductivity. However, the adverse effect of this granular stacking partly explains the lower mechanical performances of the concrete using rice husk as aggregate, irrespective of curing conditions.

Plant-based concretes cast by manual tamping have shown a same hardening kinetics of the lime binder over 10 months under natural carbonation (20 °C, 50% RH or outdoor exposure) while the strength development of rice husk concrete over time was strongly limited compared to that of hemp concrete. This was attributed to the weaker bond strength of the binder with rice husk. © The Author(s) 2018 M. Chabannes et al., Lime Hemp and Rice Husk-Based Concretes for Building Envelopes, Biobased Polymers, https://doi.org/ I 0.1007 /978-3-319-67660-9 _5

99

100

5

Conclusion and Outlooks

5

Conclusion and Outlooks

'

The accelerated carbonation curing (cyclic CO 2 exposure) at 20 °C and 65%RH was found to be effective to increment the short-term compressive strength of plant-based concretes. Therefore, it could be used as part of a block making factory.

Moist curing (95%RH) led to a strong increase in the compressive strength of lime-based mortars including C 2 S (like hydraulic lime). The hardening of lime-based binders can be significantly accelerated at early ages. Results showed that high RH and elevated temperature (50 °C here) promoted C 2 S hydration.

Nevertheless, these conditions were counterproductive for bio-based concretes since the interfacial transition zone between the particles and the binder was affected by moist curing due to excess water in the vicinity of plant aggregates.

Hence, the best way to accelerate the hardening of plant-based concretes is to establish optimal curing conditions for carbonation.

Some investigations about the shear behavior of plant-based concretes by means of triaxial compression are pioneers and have made possible the determination of the shear strength parameters. A consistent value of cohesion was achieved and attributed to the binder strength while a different peak friction angle was related to the aggregate contribution. The shear strength of plant-based concrete was found to be significant. Consequently, it should be considered for the design practice of building envelopes.

Here are some outlooks for the research presented in the book: • The compressive strength of rice husk concrete is lower than that of hemp concrete even if a same mix proportioning is used. The packing of rice husks could be enhanced by increasing the rice husk content in the concrete while reducing the binder content for trying to reduce the inter-particles porosity without increasing the density of the concrete and the environmental impact. It appears challenging to achieve a higher compressive strength than that reported in this research with vibro-compaction but it might be a good opportunity to inc~ease ductility and shear strength. Another way to increase the packing density of lime and rice husk concrete would consist in adding rice straw in the mix.

• Under natural conditions (outdoor curing) or accelerated carbonation, a further comprehensive study about the coupling effect of rel~tive hun:1idity, C?~ content and ventilation should be considered to provide optimal cunng cond1t1ons.

• In the case of precast blocks with high compaction of the mixture at the fresh stale thermal and mechanical anisotropies of hemp concrete have already been prov~n [2]. When the block is inserted in such a wa~ that the ver~ic_alload in the wall is parallel to the compaction direction, mechanical strength_ 1s mcreased bu! thermal conductivity tends to be less favorable. When the block 1s rotate~ by 90 (the load is perpendicular to the compaction direction), it is the opposite. The shear strength of the block in this configuration has every cha~ce Lobe far below that measured in this research. Attention will have to be paid to these aspects including the case of rice husk concrete.

References I. A. Arrigoni, R. Pelosato, P. Melia, G. Ruggieri, S._Sabbadini, G. Dotelli, ~i:e dcyc_leasse;sm~~; of natural building materials: The role of carbon allon, mixture components an t1anspo1 in environmental impacts of hempcrete blocks. J. Clean. Prod. !49, 1~5~-1061_(2017) .· .

2. v. Nozahic, Yers une nouvelle demarche de conception des betons ve~e'.au xAl1gnocellulos'.q~e~ basee sur la comprehension et !'amelioration de !'interface Liant/Vegeta. 1 pp 11cat1on a es granulats de chenevotte et de tige de tournesol associes a un liant ponce/chaux, Ph.D. Thesis (Clermont University, France, 2012), p. 311

• For both plant-based concretes, a more accurate approach is required to predict the shear contribution of bio-based concrete in relation to their mix proportioning.

• Further studies are needed to investigate the shear strength of low density plant-based concretes cast by manual tamping for monolithic construction.

Moreover, the size effect of specimens should be considered. A large-scale triaxial test would be more representative of the real conditions.

• There has been an increasing interest in producing blocks at an industrial scale.

These are self-supporting and typically inserted into wood frames [l]. The effect of curing conditions (and especially the COz-curing) should be explored on vibro-compacted specimens. The cumulative effect of these two processes could significantly increase the short term mechanical performances of industrial blocks (under compression and shear loading).

m"""""'""""'"''''

.,,,,,,,,,,,11111111111

100

5

Conclusion and Outlooks

5

Conclusion and Outlooks

'

The accelerated carbonation curing (cyclic CO 2 exposure) at 20 °C and 65%RH was found to be effective to increment the short-term compressive strength of plant-based concretes. Therefore, it could be used as part of a block making factory.

Moist curing (95%RH) led to a strong increase in the compressive strength of lime-based mortars including C 2 S (like hydraulic lime). The hardening of lime-based binders can be significantly accelerated at early ages. Results showed that high RH and elevated temperature (50 °C here) promoted C 2 S hydration.

Nevertheless, these conditions were counterproductive for bio-based concretes since the interfacial transition zone between the particles and the binder was affected by moist curing due to excess water in the vicinity of plant aggregates.

Hence, the best way to accelerate the hardening of plant-based concretes is to establish optimal curing conditions for carbonation.

Some investigations about the shear behavior of plant-based concretes by means of triaxial compression are pioneers and have made possible the determination of the shear strength parameters. A consistent value of cohesion was achieved and attributed to the binder strength while a different peak friction angle was related to the aggregate contribution. The shear strength of plant-based concrete was found to be significant. Consequently, it should be considered for the design practice of building envelopes.

Here are some outlooks for the research presented in the book: • The compressive strength of rice husk concrete is lower than that of hemp concrete even if a same mix proportioning is used. The packing of rice husks could be enhanced by increasing the rice husk content in the concrete while reducing the binder content for trying to reduce the inter-particles porosity without increasing the density of the concrete and the environmental impact. It appears challenging to achieve a higher compressive strength than that reported in this research with vibro-compaction but it might be a good opportunity to inc~ease ductility and shear strength. Another way to increase the packing density of lime and rice husk concrete would consist in adding rice straw in the mix.

• Under natural conditions (outdoor curing) or accelerated carbonation, a further comprehensive study about the coupling effect of rel~tive hun:1idity, C?~ content and ventilation should be considered to provide optimal cunng cond1t1ons.

• In the case of precast blocks with high compaction of the mixture at the fresh stale thermal and mechanical anisotropies of hemp concrete have already been prov~n [2]. When the block is inserted in such a wa~ that the ver~ic_alload in the wall is parallel to the compaction direction, mechanical strength_ 1s mcreased bu! thermal conductivity tends to be less favorable. When the block 1s rotate~ by 90 (the load is perpendicular to the compaction direction), it is the opposite. The shear strength of the block in this configuration has every cha~ce Lobe far below that measured in this research. Attention will have to be paid to these aspects including the case of rice husk concrete.

References I. A. Arrigoni, R. Pelosato, P. Melia, G. Ruggieri, S._Sabbadini, G. Dotelli, ~i:e dcyc_leasse;sm~~; of natural building materials: The role of carbon allon, mixture components an t1anspo1 in environmental impacts of hempcrete blocks. J. Clean. Prod. !49, 1~5~-1061_(2017) .· .

2. v. Nozahic, Yers une nouvelle demarche de conception des betons ve~e'.au xAl1gnocellulos'.q~e~ basee sur la comprehension et !'amelioration de !'interface Liant/Vegeta. 1 pp 11cat1on a es granulats de chenevotte et de tige de tournesol associes a un liant ponce/chaux, Ph.D. Thesis (Clermont University, France, 2012), p. 311

• For both plant-based concretes, a more accurate approach is required to predict the shear contribution of bio-based concrete in relation to their mix proportioning.

• Further studies are needed to investigate the shear strength of low density plant-based concretes cast by manual tamping for monolithic construction.

Moreover, the size effect of specimens should be considered. A large-scale triaxial test would be more representative of the real conditions.

• There has been an increasing interest in producing blocks at an industrial scale.

These are self-supporting and typically inserted into wood frames [l]. The effect of curing conditions (and especially the COz-curing) should be explored on vibro-compacted specimens. The cumulative effect of these two processes could significantly increase the short term mechanical performances of industrial blocks (under compression and shear loading).

m"""""'""""'"''''

.,,,,,,,,,,,11111111111

Reproduction of figures-Reference

list

Figure II-le. International Journal of Biological Macromolecules, vol. 17, no. 6, M.R. Vignon, C. Garcia-Jaldon, D. Dupeyre, Steam explosion of woody hemp chenevotte, pages No. 395-404, 1995, with permission from Elsevier.

Figure 11-4. Chemical Society Reviews, vol. 41, no. 24, D.M. Alonso, S.G. Wettstein, J.A. Dumesic, Bimetallic catalysts for upgrading of biomass to fuels and chemicals, pages No. 8075-8098, 2012-Reproduced by permission of the Royal Society of Chemistry.

Figure II-7a. Construction and Building Materials, vol. 14, no. 8, R. Jauberthie, F. Rendell, Origin of the pozzolanic effect of rice husks, pages No. 419-423, 2000, with permission from Elsevier.

Figure II-7b, c, d. Biomass and Bioenergy, vol. 25, no. 3, B.-D. Park, S.G. Wi, K.H. Lee, A.P Singh, T.-H. Yoon, Y.S. Kim, Characterization of anatomical features and silica distribution in rice husk using microscopic and micro-analytical techniques, pages No. 319-327, 2003, with permission from Elsevier.

Figures 11-6, 11-9, 11-12, IV-3, IV-12 and IV-20. Construction and Building Materials, vol. 70, M. Chabannes, J.-C. Benezet, L. Clerc, E. Garcia-Diaz, Use of raw rice husk as natural aggregate, an innovative application, pages No. 428-438, 2014, with permission from Elsevier.

Figures 111-3 and 111-4. Journal of Thermal Analysis and Calorimetry, Quantitative study of hydration of C 3S and C2 S by thermal analysis, vol. 102, no. 3, 2010, pages No. 965-973, S. Goni, F. Puertas, M. Soledad Hernandez, M. Palacios, A. Guerrero, J.S. Dolado, B. Zanga, F. Baroni, with pennission of Springer.

Figures 111-5, 111-6, 111-11, IV-31, IV-37 and IV-38. Construction and Building Materials, vol. 102, M. Chabannes, E. Garcia-Diaz, L. Clerc, J.-C. Benezet, Effect of curing conditions and Ca(OHh-treated aggregates on mechanical properties of rice husk and hemp concretes using a lime-based binder, pages No. 821-833, 2016, with permission from Elsevier.

Figure 111-7.Thermochimica Acta, vol. 444, no. 2, R.M.H. Lawrence, T.J. Mays, P. Walker, D. D' Ayala, Determination of carbonation profiles in non-hydraulic lime mortars using thermogravimetric analysis, pages No. 179-189, 2006, with permission from Elsevier.

© The Author(s) 2018 M. Chabannes et al., Lime Hemp and Rice Husk-Based Concretes for Building Envelopes, Biobased Polymers, https://doi.org/10.1007/978-3-3 I 9-67660-9

103

Reproduction of figures-Reference

list

Figure II-le. International Journal of Biological Macromolecules, vol. 17, no. 6, M.R. Vignon, C. Garcia-Jaldon, D. Dupeyre, Steam explosion of woody hemp chenevotte, pages No. 395-404, 1995, with permission from Elsevier.

Figure 11-4. Chemical Society Reviews, vol. 41, no. 24, D.M. Alonso, S.G. Wettstein, J.A. Dumesic, Bimetallic catalysts for upgrading of biomass to fuels and chemicals, pages No. 8075-8098, 2012-Reproduced by permission of the Royal Society of Chemistry.

Figure II-7a. Construction and Building Materials, vol. 14, no. 8, R. Jauberthie, F. Rendell, Origin of the pozzolanic effect of rice husks, pages No. 419-423, 2000, with permission from Elsevier.

Figure II-7b, c, d. Biomass and Bioenergy, vol. 25, no. 3, B.-D. Park, S.G. Wi, K.H. Lee, A.P Singh, T.-H. Yoon, Y.S. Kim, Characterization of anatomical features and silica distribution in rice husk using microscopic and micro-analytical techniques, pages No. 319-327, 2003, with permission from Elsevier.

Figures 11-6, 11-9, 11-12, IV-3, IV-12 and IV-20. Construction and Building Materials, vol. 70, M. Chabannes, J.-C. Benezet, L. Clerc, E. Garcia-Diaz, Use of raw rice husk as natural aggregate, an innovative application, pages No. 428-438, 2014, with permission from Elsevier.

Figures 111-3 and 111-4. Journal of Thermal Analysis and Calorimetry, Quantitative study of hydration of C 3S and C2 S by thermal analysis, vol. 102, no. 3, 2010, pages No. 965-973, S. Goni, F. Puertas, M. Soledad Hernandez, M. Palacios, A. Guerrero, J.S. Dolado, B. Zanga, F. Baroni, with pennission of Springer.

Figures 111-5, 111-6, 111-11, IV-31, IV-37 and IV-38. Construction and Building Materials, vol. 102, M. Chabannes, E. Garcia-Diaz, L. Clerc, J.-C. Benezet, Effect of curing conditions and Ca(OHh-treated aggregates on mechanical properties of rice husk and hemp concretes using a lime-based binder, pages No. 821-833, 2016, with permission from Elsevier.

Figure 111-7.Thermochimica Acta, vol. 444, no. 2, R.M.H. Lawrence, T.J. Mays, P. Walker, D. D' Ayala, Determination of carbonation profiles in non-hydraulic lime mortars using thermogravimetric analysis, pages No. 179-189, 2006, with permission from Elsevier.

© The Author(s) 2018 M. Chabannes et al., Lime Hemp and Rice Husk-Based Concretes for Building Envelopes, Biobased Polymers, https://doi.org/10.1007/978-3-3 I 9-67660-9

103

104

Reproduction of figures-Reference

list

Figure 111-9. Cement and Concrete Research, vol. 23, no. 4, C. Shi, R.L. Day, Acceleration of strength gain of lime-pozzolan cements by thermal activation, pages No. 824-832, 1993, with permission from Elsevier.

Figure 111-10. Cement and Concrete Research, vol. 34, J. Lanas, J.L.P. Bernal, M. Bello, J. I. Galindo, Mechanical properties of natural hydraulic lime-based mortars, pages No. 2191-2201, 2004, with permission from Elsevier.

Figures IV-14, IV-15, IV-40, IV-41, IV-42, IV-43 and IV-44. Construction and Building Materials, vol. 143, M. Chabannes, F. Becquart, E. Garcia-Diaz, N-E. Abriak, L. Clerc, Experimental investigation of the shear behaviour of hemp and rice husk-based concretes using triaxial compression, pages No. 621-632, 2017, with permission from Elsevier.

Figures IV-23 and IV-24. Journal of Materials Science Research, vol. 3, no. 3, R. Walker, S. Pavia, Effect of hemp's soluble components on the physical properties of hemp concrete, pages No. 12-23, 2014, with permission from JMSR. Figures IV-26, IV-27, IV-28, IV-29, IV-30, IV-32, IV-33, IV-34 and IV-36.

Construction and Building Materials, vol. 94, M. Chabannes, E. Garcia-Diaz, L. Clerc, J-C. Benezet, Studying the hardening and mechanical performances of rice husk and hemp-based building materials cured under natural and accelerated carbonation, pages No. 105-115, 2015, with permission from Elsevier.

Figure IV-39. Construction and Building Materials, vol. 66, C. Gross, P. Walker, Racking performance of timber studwork and hemp-lime walling, pages No. 429-435, 2014, with permission from Elsevier.

Bio-aggregate-based Building Materials Applications to Hemp Concretes

Edited by Sofiane Amziane Laurent Arnaud

,.

Series Editor Noel Challamel

\SIE

~WILEY

.

.

Table of Contents

First published 2013 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

iI,.,. ;;,. [

'

'

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address: ISTE Ltd 27-37 St George's Road London SW 19 4EU UK

www.iste.co.uk

John Wiley & Sons, Inc. 111 River Street Hoboken, NJ 07030 USA

Foreword . .......................................

••

Chapter 1. Environmental, Economic and Social Context of Agro-Concretes ............................

••

Vincent

NOZAHIC and Sofiane

AMZIANE

www.wiley.com

1.1. Sustainable development, construction and materials .

1.1. l. Environmental impacts of the construction sector.

1.2. Standardization and regulation: toward a © ISTE Ltd 2013 The rights of Sofiane Amziane and Laurent Arnaud to be identified as the author of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.

Libra);)' of Congress Control Number: 2012954575 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN: 978-1-84821-404-0

global

approach

........................

1.3.1. Role

of the materials

FSC www.fsc.o,g

context Paper from

responsiblesources

FS~C013604

Printed and bound in Great Britain by CPI Group (UK) Ltd., Croydon, Surrey CR0 4YY

""'"""'"'"'"""'"'"""""II I

in energy

consumption

.

..

1.3.2. What is a low-environmental-impact material?

1.3.3. Constantly-changing regulations ....

1.4. The specific case of concretes made from particles.

l .4.1. Development MIX

2

• • • • • •

1.2.1. Standardization and regulation in force ..........

1.2.2. Limitations of the normative and regulatory framework.

1.3. The materials: an increasingly crucial element ...

lignocellular

IJ

Xl

. . . . . . . . . . . . . . . of agro-concretes

of France

................

.

1.5. What does the term "Agro-concrete" mean?

1.5 .1. General definition ............. .

1.5.2. Lignocellular resources ......... .

1.5.3. General characteristics oflignocellular agro-resources

..

1.6. Conclusions 1.7. Bibliography

.. .

. ...

• • • • • • • • · · · ·

9

in the

10 13 13 13 15 19 19

,,.,,,,,,,,,,,,,,,,,,,,,,,,,,,,1,11111111111111,,.

.

.

Table of Contents

First published 2013 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

iI,.,. ;;,. [

'

'

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address: ISTE Ltd 27-37 St George's Road London SW 19 4EU UK

www.iste.co.uk

John Wiley & Sons, Inc. 111 River Street Hoboken, NJ 07030 USA

Foreword . .......................................

••

Chapter 1. Environmental, Economic and Social Context of Agro-Concretes ............................

••

Vincent

NOZAHIC and Sofiane

AMZIANE

www.wiley.com

1.1. Sustainable development, construction and materials .

1.1. l. Environmental impacts of the construction sector.

1.2. Standardization and regulation: toward a © ISTE Ltd 2013 The rights of Sofiane Amziane and Laurent Arnaud to be identified as the author of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988.

Libra);)' of Congress Control Number: 2012954575 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN: 978-1-84821-404-0

global

approach

........................

1.3.1. Role

of the materials

FSC www.fsc.o,g

context Paper from

responsiblesources

FS~C013604

Printed and bound in Great Britain by CPI Group (UK) Ltd., Croydon, Surrey CR0 4YY

""'"""'"'"'"""'"'"""""II I

in energy

consumption

.

..

1.3.2. What is a low-environmental-impact material?

1.3.3. Constantly-changing regulations ....

1.4. The specific case of concretes made from particles.

l .4.1. Development MIX

2

• • • • • •

1.2.1. Standardization and regulation in force ..........

1.2.2. Limitations of the normative and regulatory framework.

1.3. The materials: an increasingly crucial element ...

lignocellular

IJ

Xl

. . . . . . . . . . . . . . . of agro-concretes

of France

................

.

1.5. What does the term "Agro-concrete" mean?

1.5 .1. General definition ............. .

1.5.2. Lignocellular resources ......... .

1.5.3. General characteristics oflignocellular agro-resources

..

1.6. Conclusions 1.7. Bibliography

.. .

. ...

• • • • • • • • · · · ·

9

in the

10 13 13 13 15 19 19

,,.,,,,,,,,,,,,,,,,,,,,,,,,,,,,1,11111111111111,,.

vi

Bio-aggregate-based Building Materials Table of Contents

Chapter 2. Characterization of Plant-Based Aggregates .....

Vincent PICANDET

.

2.1. Microstructure of the shiv particles. . . . . . . . . . . . . . . . . . .

2.1.1. Structure of the stem of fibrous plants. . . . . . . . . . . . . . .

2.1.2. SEM observation of hemp shiv particles . . . . . . . . . . . . . . . .

2.1.3. Chemistry of the cell walls . . . . . . . . . . . . . . . . . . . . . . . .

2.1.4. Density and porosity, in the case of hemp shiv . . . . . . . . . . . .

2.2. Particle Size Distribution (PSD) . . . . . . . . . . . . . . . . . . . . . .

2.2.1. General characteristics of aggregates made from fibrous plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2.2. Fiber content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2.3. Methods for characterizing the PSD. . . . . . . . . . . . . . . . . . .

2.2.4. PSD analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2.5. Comparison of the results obtained by image analysis. . . . . . . .

2.2.6. Characterization of the geometry of the particles . . . . . . . . . . .

2.2.7. Characterization of the PSD. . . . . . . . . . . . . . . . . . . . . . . .

2.2.8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.3. Compactness and compressibility. . . . . . . . . . . . . . . . . . . . . . .

2.4. Water absorption capacity . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.5. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 3. Binders . . . . . . . .

Gilles ESCADEILLAS, Camille MAG~;~N~,'So·fi~~~A~~I~~~ · · · · · · · · · · · and Vincent NOZAHIC

\1.Portland cements.

27 28 28 30 31 35 36 36 37 38 48 52 57 58 65 66 68 69 75

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

75 3.1.1. General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

75 76 3. I .2. Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.1.3. Chemical and mineral composition . . . . . . . . . . . . . . . . . . .

77 3 .1.4. Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

77 84 3.1.5. Environmental impacts . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2. Lime. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

84 3 .2.1. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

84 3.2.2. Aerial lime. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

86 3.2.3. Natural hydraulic limes . . . . . . . . . . . . . . . . . . . . . . . . . .

89 3.3. Lime-pozzolan mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . .

92 3.3.1. Natural pozzolans. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

93 96 3.3.2. Calcined natural pozzolans: metakaolin. . . . . . . . . . . . . . . . .

3.3.3. Fly ash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 3.3.4. Blast furnace slag. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

3.4. Plaster .....................................

vii

•• •• •• . . . . .

106 106 106 108 108 110 110 111

Chapter 4. Formulation and Implementation . ................. .

Christophe LANOS,Florence COLLET,Gerard LENAINand Yves HUSTACHE

117

4.1. Objectives .................................... . .

4.1.1. Preamble ..................................

4.1.2. Traditional applications ......................... .

4.1.3. Constituents and mixture ........................ .

4.1.4. Methods of implementation ....................... .

•. •• 4.2. Rules of formulation ..........................

4.2.1. Basis of usual formulations ....................... .

4.2.2. Influence of the proportion of paste in the mixture ......... .

4.2.3. Quality of the paste and water content ................ .

4.2.4. Homogeneity of the paste ........................ .

4.2.5. The relationship between formulation and strength ......... .

4.2.6. The relationship between formulation and . thermo-hydric properties ............................

4.3. Examples of formulations .......................... .

4.3.1. Origin of the data ............................. .

4.3.2. Walling application ............................ .

4.3.3. Flooring application ........................... .

4.3.4. Roofing application ............................ .

4.3.5. Other applications .........................

•. •• 4.4. Installation techniques ...........................

•• 4.4.1. Building a wall using formwork .................... . .

4.4.2. Application by spraying .........................

4.4.3. Laying of a floor ........................

•••••• 4.4.4. Creating a roof ...........................

•. •• 4.4.5. Other uses ............................

•. •••• 4.5. Professional rules for buildings using hempcrete and hemp mortars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . • • • • • •

117 117 119 120 121 122 122 124 128 135 137

3.4.1. General ..................................

3.4.2. Production ................................

3.4.3. Chemical and mineralogical composition ...............

3.4.4. Properties .................................

3.4.5. Environmental impacts .........................

3.5. Summary ....................................

3.6. Bibliography ..................................

141 141 141 141 142 142 142 143 143 143 144 144 145 145

vi

Bio-aggregate-based Building Materials Table of Contents

Chapter 2. Characterization of Plant-Based Aggregates .....

Vincent PICANDET

.

2.1. Microstructure of the shiv particles. . . . . . . . . . . . . . . . . . .

2.1.1. Structure of the stem of fibrous plants. . . . . . . . . . . . . . .

2.1.2. SEM observation of hemp shiv particles . . . . . . . . . . . . . . . .

2.1.3. Chemistry of the cell walls . . . . . . . . . . . . . . . . . . . . . . . .

2.1.4. Density and porosity, in the case of hemp shiv . . . . . . . . . . . .

2.2. Particle Size Distribution (PSD) . . . . . . . . . . . . . . . . . . . . . .

2.2.1. General characteristics of aggregates made from fibrous plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2.2. Fiber content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2.3. Methods for characterizing the PSD. . . . . . . . . . . . . . . . . . .

2.2.4. PSD analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2.5. Comparison of the results obtained by image analysis. . . . . . . .

2.2.6. Characterization of the geometry of the particles . . . . . . . . . . .

2.2.7. Characterization of the PSD. . . . . . . . . . . . . . . . . . . . . . . .

2.2.8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.3. Compactness and compressibility. . . . . . . . . . . . . . . . . . . . . . .

2.4. Water absorption capacity . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.5. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 3. Binders . . . . . . . .

Gilles ESCADEILLAS, Camille MAG~;~N~,'So·fi~~~A~~I~~~ · · · · · · · · · · · and Vincent NOZAHIC

\1.Portland cements.

27 28 28 30 31 35 36 36 37 38 48 52 57 58 65 66 68 69 75

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

75 3.1.1. General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

75 76 3. I .2. Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.1.3. Chemical and mineral composition . . . . . . . . . . . . . . . . . . .

77 3 .1.4. Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

77 84 3.1.5. Environmental impacts . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2. Lime. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

84 3 .2.1. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

84 3.2.2. Aerial lime. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

86 3.2.3. Natural hydraulic limes . . . . . . . . . . . . . . . . . . . . . . . . . .

89 3.3. Lime-pozzolan mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . .

92 3.3.1. Natural pozzolans. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

93 96 3.3.2. Calcined natural pozzolans: metakaolin. . . . . . . . . . . . . . . . .

3.3.3. Fly ash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 3.3.4. Blast furnace slag. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

3.4. Plaster .....................................

vii

•• •• •• . . . . .

106 106 106 108 108 110 110 111

Chapter 4. Formulation and Implementation . ................. .

Christophe LANOS,Florence COLLET,Gerard LENAINand Yves HUSTACHE

117

4.1. Objectives .................................... . .

4.1.1. Preamble ..................................

4.1.2. Traditional applications ......................... .

4.1.3. Constituents and mixture ........................ .

4.1.4. Methods of implementation ....................... .

•. •• 4.2. Rules of formulation ..........................

4.2.1. Basis of usual formulations ....................... .

4.2.2. Influence of the proportion of paste in the mixture ......... .

4.2.3. Quality of the paste and water content ................ .

4.2.4. Homogeneity of the paste ........................ .

4.2.5. The relationship between formulation and strength ......... .

4.2.6. The relationship between formulation and . thermo-hydric properties ............................

4.3. Examples of formulations .......................... .

4.3.1. Origin of the data ............................. .

4.3.2. Walling application ............................ .

4.3.3. Flooring application ........................... .

4.3.4. Roofing application ............................ .

4.3.5. Other applications .........................

•. •• 4.4. Installation techniques ...........................

•• 4.4.1. Building a wall using formwork .................... . .

4.4.2. Application by spraying .........................

4.4.3. Laying of a floor ........................

•••••• 4.4.4. Creating a roof ...........................

•. •• 4.4.5. Other uses ............................

•. •••• 4.5. Professional rules for buildings using hempcrete and hemp mortars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . • • • • • •

117 117 119 120 121 122 122 124 128 135 137

3.4.1. General ..................................

3.4.2. Production ................................

3.4.3. Chemical and mineralogical composition ...............

3.4.4. Properties .................................

3.4.5. Environmental impacts .........................

3.5. Summary ....................................

3.6. Bibliography ..................................

141 141 141 141 142 142 142 143 143 143 144 144 145 145

viii

Bio-aggregate-based Building Materials

Table of Contents

4.5.1.History .............. .

4.5.2. Principles and content of the professional regulations 4.6. Bibliography .............................

145 146 152

.

Chapter 5. Mechanical Behavior . ......................... .

Laurent ARNAUD,Sofiane AMZIANE,Vincent NOZAHICand Etienne GOURLAy 5. I. Composite material ......... .

5. I. I. Making of the test tubes ... .

5.1.2. Mechanical behavior .......... .

5 .1.3. Effect of initial compression .. .

5.1.4. Effect of the nature of the binder.

5.1.5. Influence of the binder content .. .

5.1.6. Influence of the particle size ......................

5.1.7. Influence of the curing conditions .... .

5.1.8. Evolution over time ............ .

5 .1.9. Interaction between particles and binder .

5.1.10. Anisotropic behavior ...... .

5.2. Modeling of the mechanical behavior .......

5 .2.1. Empirical approach ............. .

5.2.2. Self-consistent homogenization approach 5.3. Toward the study of a stratified composite 5.4. Conclusion .................. .

5.5. Bibliography ............................

.

.

.

Cha,i)ter 6. Hygrothermal Behavior of Hempcrete . .

Laurent ARNAUD,Driss SAMRIand Etienne GOURLAy 6. I. Introduction ................ .

6.2. Heat conductivity ............ .

6.2.1. Measurement of the conductivity ...... .

6.2.2. Modeiing of the heat conductivity in dry and humid conditions .................................

6.2.3. Heat transfers ...... .

6.3. Hygrothermal transfers ..

6.3 .1. Experimental device .

6.3.2. Stresses ......... .

6.3.3. Phase changes .....................

6.3.4. Hygrothermal transfers ............. .

6.3 .5. Role of coating products applied to hempcrete 6.3.6. Conclusions ................................

153 153 154 154 157 159 162 164 165 166 167 170 171 171 173 174 175 176 179 179 180 181

.

. . .

182 185 186 186 189 191 194 196 200

6.4. Thermal characterization of various construction materials 6.4.1. Autoclaved aerated concrete 6.4.2. Vertically perforated brick 6.4.3. Hempcrete .......... .

6.4.4. Conclusions ......... .

6.5. Modeiing of coupled heat- and mass transfers 6.5.l. Introduction ............. .

6.5.2. Transfer laws ................ .

6.5.3. Transfer model: the Ki.inzel model. ... .

6.5.4. Determination of the transfer coefficients 6.5.5. Numerical modeling .

6.6. Conclusions ..

6.7. Bibliography ....... .

Chapter 7. Acoustical Properties of Hemp Concretes . .

Philippe GLE, Emmanuel GOURDONand Laurent ARNAUD .

7. I. Introduction ......................

7.2. Acoustical properties of the material on the basis of the main mechanisms . . . . . . . . . .

7 .2. l. Influence of the components ..

7 .2.2. Influence of the casting method 7 .3. Modeling the acoustical properties .

7 .3. I. Physical analysis of the acoustical pro petties being measured ..................... .

7 .3 .2. The adapted double porosity model and its parameters.

7.3.3. Experimental validation of the model .......... .

7.4. Application of the model to the acoustical characterization of shiv .

7 .4.1. Porosity of shiv .

7.4.2. Resistivity .

7.5. Conclusion ..

7.6. Bibliography .....

Chapter 8. Plant-Based Concretes in Structures: Structural Aspect- Addition of a Wooden Support to Absorb the Strain Philippe MUNOZand Didier PIPET 8.1. Introduction ......... .

8.2. Preliminaty test ...... .

8.2.1. Description of the panel ....

1x

201 202 204 205 210 211 211 212 216 217 222 235 238 243 243 244 244 249 252 253 255 257 258 258 262 264 264

267 267 269 269

viii

Bio-aggregate-based Building Materials

Table of Contents

4.5.1.History .............. .

4.5.2. Principles and content of the professional regulations 4.6. Bibliography .............................

145 146 152

.

Chapter 5. Mechanical Behavior . ......................... .

Laurent ARNAUD,Sofiane AMZIANE,Vincent NOZAHICand Etienne GOURLAy 5. I. Composite material ......... .

5. I. I. Making of the test tubes ... .

5.1.2. Mechanical behavior .......... .

5 .1.3. Effect of initial compression .. .

5.1.4. Effect of the nature of the binder.

5.1.5. Influence of the binder content .. .

5.1.6. Influence of the particle size ......................

5.1.7. Influence of the curing conditions .... .

5.1.8. Evolution over time ............ .

5 .1.9. Interaction between particles and binder .

5.1.10. Anisotropic behavior ...... .

5.2. Modeling of the mechanical behavior .......

5 .2.1. Empirical approach ............. .

5.2.2. Self-consistent homogenization approach 5.3. Toward the study of a stratified composite 5.4. Conclusion .................. .

5.5. Bibliography ............................

.

.

.

Cha,i)ter 6. Hygrothermal Behavior of Hempcrete . .

Laurent ARNAUD,Driss SAMRIand Etienne GOURLAy 6. I. Introduction ................ .

6.2. Heat conductivity ............ .

6.2.1. Measurement of the conductivity ...... .

6.2.2. Modeiing of the heat conductivity in dry and humid conditions .................................

6.2.3. Heat transfers ...... .

6.3. Hygrothermal transfers ..

6.3 .1. Experimental device .

6.3.2. Stresses ......... .

6.3.3. Phase changes .....................

6.3.4. Hygrothermal transfers ............. .

6.3 .5. Role of coating products applied to hempcrete 6.3.6. Conclusions ................................

153 153 154 154 157 159 162 164 165 166 167 170 171 171 173 174 175 176 179 179 180 181

.

. . .

182 185 186 186 189 191 194 196 200

6.4. Thermal characterization of various construction materials 6.4.1. Autoclaved aerated concrete 6.4.2. Vertically perforated brick 6.4.3. Hempcrete .......... .

6.4.4. Conclusions ......... .

6.5. Modeiing of coupled heat- and mass transfers 6.5.l. Introduction ............. .

6.5.2. Transfer laws ................ .

6.5.3. Transfer model: the Ki.inzel model. ... .

6.5.4. Determination of the transfer coefficients 6.5.5. Numerical modeling .

6.6. Conclusions ..

6.7. Bibliography ....... .

Chapter 7. Acoustical Properties of Hemp Concretes . .

Philippe GLE, Emmanuel GOURDONand Laurent ARNAUD .

7. I. Introduction ......................

7.2. Acoustical properties of the material on the basis of the main mechanisms . . . . . . . . . .

7 .2. l. Influence of the components ..

7 .2.2. Influence of the casting method 7 .3. Modeling the acoustical properties .

7 .3. I. Physical analysis of the acoustical pro petties being measured ..................... .

7 .3 .2. The adapted double porosity model and its parameters.

7.3.3. Experimental validation of the model .......... .

7.4. Application of the model to the acoustical characterization of shiv .

7 .4.1. Porosity of shiv .

7.4.2. Resistivity .

7.5. Conclusion ..

7.6. Bibliography .....

Chapter 8. Plant-Based Concretes in Structures: Structural Aspect- Addition of a Wooden Support to Absorb the Strain Philippe MUNOZand Didier PIPET 8.1. Introduction ......... .

8.2. Preliminaty test ...... .

8.2.1. Description of the panel ....

1x

201 202 204 205 210 211 211 212 216 217 222 235 238 243 243 244 244 249 252 253 255 257 258 258 262 264 264

267 267 269 269

x

Bio-aggregate-based Building Materials

8.2.2. Putting the panel in place on the bracing bank ....... .

8.2.3. Longitudinal loading and measurement of the movements · · · · · 8.2.4. Behavior of the test bank . . . .

270 271 273 8.2.5. Behavior of the wooden panel . : : : : : : : : : : : : : : : : : : : : : 274 8.3. Test on a composite panel of a wooden skeleton and hempcrete 276 8.3.1. Description of the panel ....

276 8.3.2. Emplacement of the panel on the·b~~cin~-b~~k : : : : : : : : : : : : 276 8.3.3. Vertical loading ......... .

279 8.3.4. Longitudinal loading and measur~~~~t ~f;h~ ;; 0 ~~~~n~s· : : : : : 280 8.3.5. Running of the test 281 8.3.6. Feature of the ruin ;f~he·p·a~~l: : : : : : : : : : : : : : : · · · · · · · 283 8.4. Results and comparative analysis . . . . . . . . . . . . . · · · · · · · 285 8.5. Conclusions and reflections . . . . . . . . . ............ · · · · · · · · · · 287 8.6. Acknowledgements .............. .

288 . ........... .

8.7. Bibliography . . . . . . . . . . . . ............ ' ..... .

288

Chapter 9. Examination of the Environmental Characteristics of a Banke~ Hempcrete Wall on a Wooden Skeleton, by Lifecycle Ana_Iys1~: Feedback on the LCA Experiment from 2005 .

Mane-Pierre BOUTINand Cyril FLAMIN

289

9.1. Introduction ................................. .

9 .2. Description of the products studied. . · 9.3. Method for environmental evaluation ~/bio·-~ 0 ~;c~d · · · · · · · · · · · materials ................................ .

9-1.,Lifecycle Analysis on hempcrete - methodology, working · · · · · · · hypotheses and results . . . . . . . . . . . .

9.4.1. Delimitation of the system under 9.4.2. Inventory analysis ..........

9.4.3. Impact evaluation ............

s~~~:

: : : : : :: :: : : : :: : :

. : : : : : : : : : : : · · · · ·

9.4.4. Results and interpretation of the lifecycle ............

9.5. Interpretations of the lifecycle, conclusions and reflections . . . .

9.6. Bibliography .. : : : : : : : : : ....................... ... ' ................

List of Authors ................................

Index .........................................

.

.

. '

289 291

Foreword

I am writing this foreword soon after finishing reading Sur la route du papier (On the Paper Trail) by Erik Orsenna: a wondrous journey, a lesson in history but also, and above all, a revelation about the workings of globalization. Paper is a harmless fibrous pulp - originally created from old rags, and later on and to date, from wood - which, filtered in the form of a thin layer, has enabled the most 1 abstract creations of the human mind to be promulgated and become immortal.

Though it has long been decried for the environmental consequences of its production, paper has now acquired a stamp of eco-friendliness thanks to the constant improvement of forestry and forest management, the manufacturing procedures and recycling. Is there any other "bio-sourced" material that has had a more profound impact on the development of civilization than paper? Assuredly not.

292 294 294 298 303 305 306 310

In another context, is there any other material that has made a greater contribution to the human race's economic development for over a century, and to the mass development of infrastructures that that development has required, than concrete? Along with petroleum (for mobility) and silicon (for information and communication technology (ICT)), this artificial rock is one of the material foundations of our so-called developed societies. Concrete has enabled us to harness the energy from rivers, to build ports and airports, levees, sewage systems, roads, bridges, tunnels and more buildings than any other material.

Yet this material, a mixture of cement, sand and gravel which we simply call

"concrete", is in fact only one of the representatives of a broad category. After all,

..

313

.

315

what is a concrete, if not a composite material made up of granular particles and a "glue" or binder holding everything together? According to that logic, bitumen concrete - that of the asphalt paving that now covers our roads in an almost 1 And, recently - but this is less noble - to package practically all the goods that we produce, in the form of cartons, boxes and bags.

x

Bio-aggregate-based Building Materials

8.2.2. Putting the panel in place on the bracing bank ....... .

8.2.3. Longitudinal loading and measurement of the movements · · · · · 8.2.4. Behavior of the test bank . . . .

270 271 273 8.2.5. Behavior of the wooden panel . : : : : : : : : : : : : : : : : : : : : : 274 8.3. Test on a composite panel of a wooden skeleton and hempcrete 276 8.3.1. Description of the panel ....

276 8.3.2. Emplacement of the panel on the·b~~cin~-b~~k : : : : : : : : : : : : 276 8.3.3. Vertical loading ......... .

279 8.3.4. Longitudinal loading and measur~~~~t ~f;h~ ;; 0 ~~~~n~s· : : : : : 280 8.3.5. Running of the test 281 8.3.6. Feature of the ruin ;f~he·p·a~~l: : : : : : : : : : : : : : : · · · · · · · 283 8.4. Results and comparative analysis . . . . . . . . . . . . . · · · · · · · 285 8.5. Conclusions and reflections . . . . . . . . . ............ · · · · · · · · · · 287 8.6. Acknowledgements .............. .

288 . ........... .

8.7. Bibliography . . . . . . . . . . . . ............ ' ..... .

288

Chapter 9. Examination of the Environmental Characteristics of a Banke~ Hempcrete Wall on a Wooden Skeleton, by Lifecycle Ana_Iys1~: Feedback on the LCA Experiment from 2005 .

Mane-Pierre BOUTINand Cyril FLAMIN

289

9.1. Introduction ................................. .

9 .2. Description of the products studied. . · 9.3. Method for environmental evaluation ~/bio·-~ 0 ~;c~d · · · · · · · · · · · materials ................................ .

9-1.,Lifecycle Analysis on hempcrete - methodology, working · · · · · · · hypotheses and results . . . . . . . . . . . .

9.4.1. Delimitation of the system under 9.4.2. Inventory analysis ..........

9.4.3. Impact evaluation ............

s~~~:

: : : : : :: :: : : : :: : :

. : : : : : : : : : : : · · · · ·

9.4.4. Results and interpretation of the lifecycle ............

9.5. Interpretations of the lifecycle, conclusions and reflections . . . .

9.6. Bibliography .. : : : : : : : : : ....................... ... ' ................

List of Authors ................................

Index .........................................

.

.

. '

289 291

Foreword

I am writing this foreword soon after finishing reading Sur la route du papier (On the Paper Trail) by Erik Orsenna: a wondrous journey, a lesson in history but also, and above all, a revelation about the workings of globalization. Paper is a harmless fibrous pulp - originally created from old rags, and later on and to date, from wood - which, filtered in the form of a thin layer, has enabled the most 1 abstract creations of the human mind to be promulgated and become immortal.

Though it has long been decried for the environmental consequences of its production, paper has now acquired a stamp of eco-friendliness thanks to the constant improvement of forestry and forest management, the manufacturing procedures and recycling. Is there any other "bio-sourced" material that has had a more profound impact on the development of civilization than paper? Assuredly not.

292 294 294 298 303 305 306 310

In another context, is there any other material that has made a greater contribution to the human race's economic development for over a century, and to the mass development of infrastructures that that development has required, than concrete? Along with petroleum (for mobility) and silicon (for information and communication technology (ICT)), this artificial rock is one of the material foundations of our so-called developed societies. Concrete has enabled us to harness the energy from rivers, to build ports and airports, levees, sewage systems, roads, bridges, tunnels and more buildings than any other material.

Yet this material, a mixture of cement, sand and gravel which we simply call

"concrete", is in fact only one of the representatives of a broad category. After all,

..

313

.

315

what is a concrete, if not a composite material made up of granular particles and a "glue" or binder holding everything together? According to that logic, bitumen concrete - that of the asphalt paving that now covers our roads in an almost 1 And, recently - but this is less noble - to package practically all the goods that we produce, in the form of cartons, boxes and bags.

x11

Bio-aggregate-based Building Materials

monopolistic fashion - may be a serious challenger to cement concrete for the title of kingpin material in our infrastructures. Between them, these two materials alone constitute almost the totality of the "skeleton" of our lands. However, the intensive usage of these materials is not without consequences, either through greenhouse gas emissions or by the exhaustion of natural resources, be they fossil or mineral.

It might be tempting to leave the topic at that, unless for anecdotal purposes.

However, there are at least two other concretes which merit our attention. The first is at least as widespread as cement and bitumen concretes on a worldwide scale; yet it is largely overlooked in our societies. Quite simply it is crude earth (not fired or baked like terracotta), which should, more correctly, be dubbed "clay concrete", because it is its fine-grained constituent - clay - which, upon interaction with water as in the case of cement concrete, ensures the cohesion of the larger grains. In various forms - compacted, molded, pasted or plastered - it provides shelter to over a quarter of the world's population. In France alone, the patrimony built of crude earth represents over a million houses. In the hands of master craftsmen and expert architects, the use of earth is fully capable of delivering on our desires for comfort and aesthetic beauty, whilst also satisfying our desire for eco-modernity.

This book is devoted to a fourth concrete, or rather a fourth family of concretes; original and promising from more than one point of view, which would seem to exhibit all the advantages of paper and earth, whilst still offering the convenience of use of our major industrial concretes. Contrary to popular opinion, sand and other granular (particulate) minerals are not an inexhaustible resource. Unless we wish to inflict irreparable damage on the environment, the time has come for recycling, or for using bio-sourced particulates, which is essentially the same thing. This is the path _.adopted by agro-concretes and, in particular, hemp concretes. France is the largest producer in Europe of Cannabis Saliva, whose fibers have been used to make rope for centuries. Yet this fast-growing plant, well adapted to temperate climates, harbors many other resources. Its stem, of a highly porous and therefore very lightweight wood, when ground up makes a surprising aggregate. Surprising, not on a mechanical level - the only level which truly counts for mineral aggregates, with cleanliness and shape in joint second place - but surprising, primarily, on a functional level: the level of hygrothermal equilibrium and acoustic properties.

Looking at the proliferation of synthetic materials available on the market, one might think that thermal, hydra! and acoustic comfort is a domain in which the materials available - particularly when these materials are used in combination have nearly reached the optimum desired. Polymer foams and organic and inorganic aerogels have extremely low thermal diffusivity and air permeability, which are difficult to better in the race toward very low values. Yet they lack inertia. When combined with other materials - or, even better, when a solid-to-liquid "phasechanging" material such as paraffin or a salt is added into the mixture - they

Foreword

x111

(apparently) acquire the thermal inertia that they lack, by absorbing and reflecting the latent heat of fusion. In spite of their remarkable performances, these insulating materials still lack the "breathability" of ce1tain natural materials, related to the capacity for absorption, transfer and phase-change of water in vapor and liquid form - all properties which depend on the characteristics of the porous space of the material and the thermal and hydric coupling which manifests itself in that space.

In the face of the complexity of combinations of synthetic materials employed to ensure an acceptable degree of comfort, agro-concretes and hemp concretes in pa1ticular offer a simple solution, which draws upon the exceptional porous texture - nearly always hierarchical - of certain plant structures. However, in order to take advantage of this property in terms of hygrothermal exchanges, the binder used must be able to work with the granular material rather than counteracting its properties.

The authors of this book present us with the elements, drawn directly from research, that help us comprehend the propetties, function and formulation of agroconcretes. It is undoubtedly true that such concretes can never stand up to high- or ultra-high-performance mineral concretes, but it is not their intention to do so. First and foremost, they are intended to be insulating materials. Therefore, their primary intention is to sustainably ensure the comfort and durability of the dwelling, including the moderately dense dwellings towards which we are now tending.

This book has another virtue. It leads us to reflect on the physical bases for our criteria of "high environmental quality", which are still largely founded upon the segmentation and selection of a few physical properties. The very least that can be said is that this manner of proceeding is not hugely well-adapted to materials in which there is extensive coupling between properties. This is precisely the case where bio-sourced materials are concerned. Let us hope that this book is distributed as widely as possible, so that a global, "performance-oriented" approach can finally emerge.

Henri VANDAMME IFSTTAR December 2012

x11

Bio-aggregate-based Building Materials

monopolistic fashion - may be a serious challenger to cement concrete for the title of kingpin material in our infrastructures. Between them, these two materials alone constitute almost the totality of the "skeleton" of our lands. However, the intensive usage of these materials is not without consequences, either through greenhouse gas emissions or by the exhaustion of natural resources, be they fossil or mineral.

It might be tempting to leave the topic at that, unless for anecdotal purposes.

However, there are at least two other concretes which merit our attention. The first is at least as widespread as cement and bitumen concretes on a worldwide scale; yet it is largely overlooked in our societies. Quite simply it is crude earth (not fired or baked like terracotta), which should, more correctly, be dubbed "clay concrete", because it is its fine-grained constituent - clay - which, upon interaction with water as in the case of cement concrete, ensures the cohesion of the larger grains. In various forms - compacted, molded, pasted or plastered - it provides shelter to over a quarter of the world's population. In France alone, the patrimony built of crude earth represents over a million houses. In the hands of master craftsmen and expert architects, the use of earth is fully capable of delivering on our desires for comfort and aesthetic beauty, whilst also satisfying our desire for eco-modernity.

This book is devoted to a fourth concrete, or rather a fourth family of concretes; original and promising from more than one point of view, which would seem to exhibit all the advantages of paper and earth, whilst still offering the convenience of use of our major industrial concretes. Contrary to popular opinion, sand and other granular (particulate) minerals are not an inexhaustible resource. Unless we wish to inflict irreparable damage on the environment, the time has come for recycling, or for using bio-sourced particulates, which is essentially the same thing. This is the path _.adopted by agro-concretes and, in particular, hemp concretes. France is the largest producer in Europe of Cannabis Saliva, whose fibers have been used to make rope for centuries. Yet this fast-growing plant, well adapted to temperate climates, harbors many other resources. Its stem, of a highly porous and therefore very lightweight wood, when ground up makes a surprising aggregate. Surprising, not on a mechanical level - the only level which truly counts for mineral aggregates, with cleanliness and shape in joint second place - but surprising, primarily, on a functional level: the level of hygrothermal equilibrium and acoustic properties.

Looking at the proliferation of synthetic materials available on the market, one might think that thermal, hydra! and acoustic comfort is a domain in which the materials available - particularly when these materials are used in combination have nearly reached the optimum desired. Polymer foams and organic and inorganic aerogels have extremely low thermal diffusivity and air permeability, which are difficult to better in the race toward very low values. Yet they lack inertia. When combined with other materials - or, even better, when a solid-to-liquid "phasechanging" material such as paraffin or a salt is added into the mixture - they

Foreword

x111

(apparently) acquire the thermal inertia that they lack, by absorbing and reflecting the latent heat of fusion. In spite of their remarkable performances, these insulating materials still lack the "breathability" of ce1tain natural materials, related to the capacity for absorption, transfer and phase-change of water in vapor and liquid form - all properties which depend on the characteristics of the porous space of the material and the thermal and hydric coupling which manifests itself in that space.

In the face of the complexity of combinations of synthetic materials employed to ensure an acceptable degree of comfort, agro-concretes and hemp concretes in pa1ticular offer a simple solution, which draws upon the exceptional porous texture - nearly always hierarchical - of certain plant structures. However, in order to take advantage of this property in terms of hygrothermal exchanges, the binder used must be able to work with the granular material rather than counteracting its properties.

The authors of this book present us with the elements, drawn directly from research, that help us comprehend the propetties, function and formulation of agroconcretes. It is undoubtedly true that such concretes can never stand up to high- or ultra-high-performance mineral concretes, but it is not their intention to do so. First and foremost, they are intended to be insulating materials. Therefore, their primary intention is to sustainably ensure the comfort and durability of the dwelling, including the moderately dense dwellings towards which we are now tending.

This book has another virtue. It leads us to reflect on the physical bases for our criteria of "high environmental quality", which are still largely founded upon the segmentation and selection of a few physical properties. The very least that can be said is that this manner of proceeding is not hugely well-adapted to materials in which there is extensive coupling between properties. This is precisely the case where bio-sourced materials are concerned. Let us hope that this book is distributed as widely as possible, so that a global, "performance-oriented" approach can finally emerge.

Henri VANDAMME IFSTTAR December 2012

Chapter 1

Environmental, Economic and Social Context of Agro-Concretes

1.1. Sustainable development, construction and materials

After decades of virtuous and limitless consumption, the evidence is incontrovertible: human activities are not without impact on the environment and on humans themselves. It was not until 1987, with the Brundtland Commission [UNI 87], that this observation gave rise to a new concept: sustainable development. The report published by this commission, Our Common Future, defines the term as follows:

,.

"Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs." [UNI 87] Thereafter, this concept has pervaded modern societies, ultimately becoming a political and economic issue, and an issue of the very survival of the human race ...

All human activities - industry, construction, agriculture, energy, transport, etc. - now have to deal with so-called "sustainable development" issues. The rep01t unveiled by the United Nations Environment Program (UNEP) [UNE 09] constitutes an overview of the evolution of our societies since the publication of the Brundtland Report. The following quote, taken from that text, highlights the enormity of the challenge: "There are no major issues raised in Our Common Future for which the foreseeable trends are favourable." [UNE 07]

Chapter written by Vincent NOZAHIC and Sofiane AMZIANE.

Chapter 1

Environmental, Economic and Social Context of Agro-Concretes

1.1. Sustainable development, construction and materials

After decades of virtuous and limitless consumption, the evidence is incontrovertible: human activities are not without impact on the environment and on humans themselves. It was not until 1987, with the Brundtland Commission [UNI 87], that this observation gave rise to a new concept: sustainable development. The report published by this commission, Our Common Future, defines the term as follows:

,.

"Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs." [UNI 87] Thereafter, this concept has pervaded modern societies, ultimately becoming a political and economic issue, and an issue of the very survival of the human race ...

All human activities - industry, construction, agriculture, energy, transport, etc. - now have to deal with so-called "sustainable development" issues. The rep01t unveiled by the United Nations Environment Program (UNEP) [UNE 09] constitutes an overview of the evolution of our societies since the publication of the Brundtland Report. The following quote, taken from that text, highlights the enormity of the challenge: "There are no major issues raised in Our Common Future for which the foreseeable trends are favourable." [UNE 07]

Chapter written by Vincent NOZAHIC and Sofiane AMZIANE.

2

Bio-aggregate-based Building Materials

1.1.1. Environmental impacts of the constmction sector Above all, we must remember that the concept of sustainable development dealt with locally is often linked to problems on a worldwide scale, such as global warming or the gradual exhaustion of resources. These two criteria constitute the points of no return for our civilization.

As regards the climate, the scientific works of the IPCC 1 serve as a referential framework. The second assessment report (SAR) published by this organization in 1995 [IPC 95] concludes that the "the balance of evidence suggests a discernible human influence on global climate". A mere two years later, on the basis of this report and the UN Framework Convention on Climate Change [UNI 92], the international political debates culminated in the Kyoto Protocol [UNI 98]. This text commits the countries which have ratified it to reduce their GHG 2 emissions by 5 .2% in comparison to their level in 1990 over the period 2008-20 l 2. The protocol came into force in 2005 and therefore will conclude in 2012. Owing to its use of nuclear and hydroelectric energy, which do not produce much GHG, France is committed to maintaining these levels of emissions.

For its part, the construction sector (residential and tertiary), much like the agricultural or industrial sectors, finds itself facing significant challenges in terms of reducing GHG emissions and energy consumption. The figures speak for themselves, but they must be analyzed seriously. Indeed, it is not always entirely clear what data have been taken into account when producing the figures, particularly in terms of drawing the distinction between a building's function and its construction:

Environmental, Economic and Social Context of Agro-Concretes

3

However, while climate change represents an alarming phenomenon, it is not the only point that needs to be taken into account. The natural resources needed for the perpetuation of human activities and societies are, for the_most part, fi111teand exhaustible. Similar to the threat of global warming, exhaustion of resources - be they minerals or arable land - is a major point of concern which will inevitably ~e_ad us to change our ways before the current century is out [OEC 08]. The_ act1v1t1es relating to construction and to public projects, while they do not necessanly r~qu1re materials to be used which come from exhaustible sources (with the exception of road infrastructures, which consume bitumen), constitute the single greatest cause of consumption of natural resources (31 % in Europe [SER 09]). Furthermore, this consumption causes a large amount of waste production, even though 97% of the waste produced by construction and public works in France are inert [IFE 08] and are subject to a policy of value-creation. In France, the amount of waste generated by this domain equated 343 million tons in 2004, 44% of the total mass [PEU 08].

In summary, environment:

the construction

sector battles

four main impacts on the

- Its GHG emissions; - Its energy consumption; - Its consumption of natural resources; - Its waste production.

1.2. Standardization and regulation: toward a global approach -'Total GHG emissions from both energetic and non-energetic sources (e.g. agriculture, forestry, etc.): 7.9% on a global scale [IPC 07], 40% on the scale of the US [USD 11] and 18% on the scale of France in 2007 (CGD I OJ for all residential/tertiary, institutional and commercial consumption (heating, specific electricity, hot water, cooking, etc.); - Final electrical energy consumption 3 : 41 % on the scale of the US in 20 I 0 [USD 11] and 43.4% on the scale of France in 2008 [RIL 06; CGD 09] for all residential/te1tiary, institutional and commercial use. These figures do not include the fossil energy required to produce the electricity.

1.2. 1. Standardization and regulation in force The legislation in charge of regulating these major impacts ?f the sector is_a relatively recent phenomenon. The European framework was sohd1fied 1112002 with the publication of the Energy Performance of Buildings Directive (EPBD). In the context of France, the successive "reglementations thermiques" (thermal regulations) RT 2000 and RT 2005 [FFB 09] follow this document. More recently, the Loi Grenelle J (First Conference Law) of 3 August 2009 defined the Plan Batiment Grenelfe4 (Conference Building Plan), launched in January 2009 (see Figure 1.1):

I IPCC: Intergovernmental Panel on Climate Change 2 GHG: Greenhouse Gas 3 Final energy is directly usable energy, bought and charged by each customer - e.g. liters of gasoline at the pumps.

4 www.plan-batiment.legrenelle-environnement.fr

(02/09/10)

2

Bio-aggregate-based Building Materials

1.1.1. Environmental impacts of the constmction sector Above all, we must remember that the concept of sustainable development dealt with locally is often linked to problems on a worldwide scale, such as global warming or the gradual exhaustion of resources. These two criteria constitute the points of no return for our civilization.

As regards the climate, the scientific works of the IPCC 1 serve as a referential framework. The second assessment report (SAR) published by this organization in 1995 [IPC 95] concludes that the "the balance of evidence suggests a discernible human influence on global climate". A mere two years later, on the basis of this report and the UN Framework Convention on Climate Change [UNI 92], the international political debates culminated in the Kyoto Protocol [UNI 98]. This text commits the countries which have ratified it to reduce their GHG 2 emissions by 5 .2% in comparison to their level in 1990 over the period 2008-20 l 2. The protocol came into force in 2005 and therefore will conclude in 2012. Owing to its use of nuclear and hydroelectric energy, which do not produce much GHG, France is committed to maintaining these levels of emissions.

For its part, the construction sector (residential and tertiary), much like the agricultural or industrial sectors, finds itself facing significant challenges in terms of reducing GHG emissions and energy consumption. The figures speak for themselves, but they must be analyzed seriously. Indeed, it is not always entirely clear what data have been taken into account when producing the figures, particularly in terms of drawing the distinction between a building's function and its construction:

Environmental, Economic and Social Context of Agro-Concretes

3

However, while climate change represents an alarming phenomenon, it is not the only point that needs to be taken into account. The natural resources needed for the perpetuation of human activities and societies are, for the_most part, fi111teand exhaustible. Similar to the threat of global warming, exhaustion of resources - be they minerals or arable land - is a major point of concern which will inevitably ~e_ad us to change our ways before the current century is out [OEC 08]. The_ act1v1t1es relating to construction and to public projects, while they do not necessanly r~qu1re materials to be used which come from exhaustible sources (with the exception of road infrastructures, which consume bitumen), constitute the single greatest cause of consumption of natural resources (31 % in Europe [SER 09]). Furthermore, this consumption causes a large amount of waste production, even though 97% of the waste produced by construction and public works in France are inert [IFE 08] and are subject to a policy of value-creation. In France, the amount of waste generated by this domain equated 343 million tons in 2004, 44% of the total mass [PEU 08].

In summary, environment:

the construction

sector battles

four main impacts on the

- Its GHG emissions; - Its energy consumption; - Its consumption of natural resources; - Its waste production.

1.2. Standardization and regulation: toward a global approach -'Total GHG emissions from both energetic and non-energetic sources (e.g. agriculture, forestry, etc.): 7.9% on a global scale [IPC 07], 40% on the scale of the US [USD 11] and 18% on the scale of France in 2007 (CGD I OJ for all residential/tertiary, institutional and commercial consumption (heating, specific electricity, hot water, cooking, etc.); - Final electrical energy consumption 3 : 41 % on the scale of the US in 20 I 0 [USD 11] and 43.4% on the scale of France in 2008 [RIL 06; CGD 09] for all residential/te1tiary, institutional and commercial use. These figures do not include the fossil energy required to produce the electricity.

1.2. 1. Standardization and regulation in force The legislation in charge of regulating these major impacts ?f the sector is_a relatively recent phenomenon. The European framework was sohd1fied 1112002 with the publication of the Energy Performance of Buildings Directive (EPBD). In the context of France, the successive "reglementations thermiques" (thermal regulations) RT 2000 and RT 2005 [FFB 09] follow this document. More recently, the Loi Grenelle J (First Conference Law) of 3 August 2009 defined the Plan Batiment Grenelfe4 (Conference Building Plan), launched in January 2009 (see Figure 1.1):

I IPCC: Intergovernmental Panel on Climate Change 2 GHG: Greenhouse Gas 3 Final energy is directly usable energy, bought and charged by each customer - e.g. liters of gasoline at the pumps.

4 www.plan-batiment.legrenelle-environnement.fr

(02/09/10)

List of Authors

,.

Sofiane AMZIANE Blaise Pascal University Clermond-F enand France

Philippe GLE ENTPE Lyon France

Laurent ARNAUD ENTPE Lyon France

Emmanuel GOURDON ENTPE Lyon France

Marie-Pierre BOUTIN BRGM France

Y Etienne GOURI.,A ENTPE Lyon France

Florence COLLET University ofRennes l France

Yves HUSTACHE Eco-Innovation & Strategie France

Gilles ESCADEILLAS LMDC Toulouse France

Christophe LANOS University ofRennes l France

Cyril FLAMIN !NRA France

Gerard LENAIN SOC INNOV ANTE CONSTRUC CHANVRE (SI2C) France

List of Authors

,.

Sofiane AMZIANE Blaise Pascal University Clermond-F enand France

Philippe GLE ENTPE Lyon France

Laurent ARNAUD ENTPE Lyon France

Emmanuel GOURDON ENTPE Lyon France

Marie-Pierre BOUTIN BRGM France

Y Etienne GOURI.,A ENTPE Lyon France

Florence COLLET University ofRennes l France

Yves HUSTACHE Eco-Innovation & Strategie France

Gilles ESCADEILLAS LMDC Toulouse France

Christophe LANOS University ofRennes l France

Cyril FLAMIN !NRA France

Gerard LENAIN SOC INNOV ANTE CONSTRUC CHANVRE (SI2C) France

314

Bio-aggregate-based Building Materials

Camille MAGNIONT IUT Toulouse France Philippe MUNOZ CRDA LyceeARAGO Reims France Vincent N0ZAHIC Blaise Pascal University Clermond-F errand France Vincent PICANDET University of South Brittany France

,.

Didier PI PET CRDA LyceeARAGO Reims France Driss SAMRI ENTPE Lyon France

Index

Henri VANDAMME IFSTTAR France A

Absorption, 68, 69, 249, 250 ACERMI, 9 Acoustical, 243-263 Aerated lime, 86-92, 120, 125, 136, 159,164,247 Agro-concretes, 1-19 Arithmetic mean, 58, 60, 61 Ash, 34, 35 Average elongation, 57, 58

Confinement stress, 35 Construction details, 150 Convexity, 42, 43, 52, 53, 66 Convexity ratio, 42, 52, 53 Cortex, 29 D

Blast furnace slag, 103- 106 Bracing tests, 287

Defibration, 30, 34-37, 39, 49, 52, 65,259 Density, 35, 36 Distribution model, 59-65 Dynamic bulk modulus, 253, 254, 257,258 Dynamic density, 253, 256-258

C

E

Cambium, 28 Capillary absorption coefficient, 92 Casting, 28, 65, 66, 68, 69, 118, 120, 123,244,249 Cellulose, 15, 32, 33 Chemical composition, 15, 16 Clinker, 76-78, 84, 105, 168 Compacting, 28, 66, 67, 121, 124, 125, 131, 139, 144, 154,157,158, 162-164, 170, 174-176

Eco-materials, 11, 12 Elasticity modulus, 155, 158, 163, 174 Ellipse, 44-47, 51-54 Elongation, 43, 45- 47, 50, 57-58, 65, 175 Environmental impacts, 2-3, 84, 92, 100, 101, 103, 106, 110 Epidermis, 28

B

314

Bio-aggregate-based Building Materials

Camille MAGNIONT IUT Toulouse France Philippe MUNOZ CRDA LyceeARAGO Reims France Vincent N0ZAHIC Blaise Pascal University Clermond-F errand France Vincent PICANDET University of South Brittany France

,.

Didier PI PET CRDA LyceeARAGO Reims France Driss SAMRI ENTPE Lyon France

Index

Henri VANDAMME IFSTTAR France A

Absorption, 68, 69, 249, 250 ACERMI, 9 Acoustical, 243-263 Aerated lime, 86-92, 120, 125, 136, 159,164,247 Agro-concretes, 1-19 Arithmetic mean, 58, 60, 61 Ash, 34, 35 Average elongation, 57, 58

Confinement stress, 35 Construction details, 150 Convexity, 42, 43, 52, 53, 66 Convexity ratio, 42, 52, 53 Cortex, 29 D

Blast furnace slag, 103- 106 Bracing tests, 287

Defibration, 30, 34-37, 39, 49, 52, 65,259 Density, 35, 36 Distribution model, 59-65 Dynamic bulk modulus, 253, 254, 257,258 Dynamic density, 253, 256-258

C

E

Cambium, 28 Capillary absorption coefficient, 92 Casting, 28, 65, 66, 68, 69, 118, 120, 123,244,249 Cellulose, 15, 32, 33 Chemical composition, 15, 16 Clinker, 76-78, 84, 105, 168 Compacting, 28, 66, 67, 121, 124, 125, 131, 139, 144, 154,157,158, 162-164, 170, 174-176

Eco-materials, 11, 12 Elasticity modulus, 155, 158, 163, 174 Ellipse, 44-47, 51-54 Elongation, 43, 45- 47, 50, 57-58, 65, 175 Environmental impacts, 2-3, 84, 92, 100, 101, 103, 106, 110 Epidermis, 28

B

316

Index

Bio-aggregate-based Building Materials

F

Factor of 4, 4 Feret, 42-44, 54, 58, 65 FHS, 35 Fibers, 10, 13-15 17 27-29 33-45,52,54,~5.~ 5, 93 09 , 175,289,290,296,301 Flatness, 58 Fly ash, l O1-103 Formulation, 117-152 Frame density, 258,259,261

,i

G

Geometric mean, 58, 60, 63, 65, 66 Grenelle, 3, 4 H

Hemicelluloses, 15, 33 Hemp shiv, 28 HQE, 6,294 HS, 35 Hydration, 78-81, 96 Hydraulic limes, 89-92 Hydric, 83, 88, 92, 96, 100, 103 105,110 ' Hydric'°properties, 83, 88, 92, 96, 100, 103, 105, 110

I Image analysis, 39-47 Installation, 143-145 Intra-particle porosity, 164,258,261

K Kaolinite, 97

L LCA (Life-Cycle Analysis) 4 8 Lignin, 33, 34 ' '

Lime-pozzolan binders, 92-106 Lipids, 31, 34 Loading cycle, 156, 285 Longitudinal loading, 271, 272 280,281 ' M

Major axis, 43, 44, 54 Mechanical properties 81-82 88 91-92, 99-100, 102, '105, 109 ' Mechanical strength(s), 81, 87, 88, 91-93, 99, 102-105, 110, 111, 128, 137, 153, 154, 167, 170, 174-176,267 Meristem, 29 Metakaolin, 96 Minor axis, 43, 54 N Natural hydraulic limes (NHLs) 89-92 ' Natural pozzolans, 93-96

p Particle size distribution (PSD) 36, 37 ' Pectins, 15, 16, 18,31,33,3 4 Phloem, 17, 28 Plant cell walls, 32, 33 Plaster, l 06-11 O Porosity, 30 Portland cements, 75-84 Pozzolanic admixtures, 75 80 81 ' ' ' 93, 101 Pozzolanic reaction 11 80 8 l 92 ' ' ' ' ' 95, 98, 100, 102 PREBAT, 5, 167 Principle, 146-152 Professional regulations 119 146 147, 151, 152, 154, 159 ' ' Projected area, 41-52, 54, 55

Projection, 38, 145, 170-173, 238,267,297,299

Strength test, 282, 283, 285 Sustainability, 6, 12 Sustainable development, 1-3

R Resistivity, 262, 263 Resolution, 40, 41, 53 Rigidity, 15, 33,120,175,176, 282,283,285,286 Rigidity test, 282, 285 RT 2012, 4, 7,238

s Sieving, 38, 39 Sound absorption, 245-251, 252, 256,258 Standard deviation, 46, 58-61, 63, 65,66,260

T

Thermal properties, 75, 83, 100, 103,105,111,145,179 Thresholding, 41 Tortuosity, 212,256,257,264

v,w,x Vertical loading, 279 Viscous characteristic length, 256 Waxes, 15, 31, 34 Xylem, 15, 17, 28, 29, 34

317

316

Index

Bio-aggregate-based Building Materials

F

Factor of 4, 4 Feret, 42-44, 54, 58, 65 FHS, 35 Fibers, 10, 13-15 17 27-29 33-45,52,54,~5.~ 5, 93 09 , 175,289,290,296,301 Flatness, 58 Fly ash, l O1-103 Formulation, 117-152 Frame density, 258,259,261

,i

G

Geometric mean, 58, 60, 63, 65, 66 Grenelle, 3, 4 H

Hemicelluloses, 15, 33 Hemp shiv, 28 HQE, 6,294 HS, 35 Hydration, 78-81, 96 Hydraulic limes, 89-92 Hydric, 83, 88, 92, 96, 100, 103 105,110 ' Hydric'°properties, 83, 88, 92, 96, 100, 103, 105, 110

I Image analysis, 39-47 Installation, 143-145 Intra-particle porosity, 164,258,261

K Kaolinite, 97

L LCA (Life-Cycle Analysis) 4 8 Lignin, 33, 34 ' '

Lime-pozzolan binders, 92-106 Lipids, 31, 34 Loading cycle, 156, 285 Longitudinal loading, 271, 272 280,281 ' M

Major axis, 43, 44, 54 Mechanical properties 81-82 88 91-92, 99-100, 102, '105, 109 ' Mechanical strength(s), 81, 87, 88, 91-93, 99, 102-105, 110, 111, 128, 137, 153, 154, 167, 170, 174-176,267 Meristem, 29 Metakaolin, 96 Minor axis, 43, 54 N Natural hydraulic limes (NHLs) 89-92 ' Natural pozzolans, 93-96

p Particle size distribution (PSD) 36, 37 ' Pectins, 15, 16, 18,31,33,3 4 Phloem, 17, 28 Plant cell walls, 32, 33 Plaster, l 06-11 O Porosity, 30 Portland cements, 75-84 Pozzolanic admixtures, 75 80 81 ' ' ' 93, 101 Pozzolanic reaction 11 80 8 l 92 ' ' ' ' ' 95, 98, 100, 102 PREBAT, 5, 167 Principle, 146-152 Professional regulations 119 146 147, 151, 152, 154, 159 ' ' Projected area, 41-52, 54, 55

Projection, 38, 145, 170-173, 238,267,297,299

Strength test, 282, 283, 285 Sustainability, 6, 12 Sustainable development, 1-3

R Resistivity, 262, 263 Resolution, 40, 41, 53 Rigidity, 15, 33,120,175,176, 282,283,285,286 Rigidity test, 282, 285 RT 2012, 4, 7,238

s Sieving, 38, 39 Sound absorption, 245-251, 252, 256,258 Standard deviation, 46, 58-61, 63, 65,66,260

T

Thermal properties, 75, 83, 100, 103,105,111,145,179 Thresholding, 41 Tortuosity, 212,256,257,264

v,w,x Vertical loading, 279 Viscous characteristic length, 256 Waxes, 15, 31, 34 Xylem, 15, 17, 28, 29, 34

317