Alec Borrill 07027752 ADP022N Applied Technology in Architecture
Prototyping Architecture 2008 Carsten Vellguth
Introduction Materiality in Cuba For my ATA Prototyping Architecture project I wish to investigate and analyse the use of Hemp as a viable building element in the context of Cuba's construction industry. Within Unit 2 we are working on three separate design projects, mine being a vocational school for 12-16 year olds in the city of Sancti Spiritus.
A European view of ‘specification and ordering’ of components for a building is no use here. As a result many of the buildings throughout Cuba have a very limited palette of materials, consisting of mainly concrete and brick. Glass is almost exclusively reserved for buildings where air-conditioning is present, such as hotels (tourism – high priority) Proposing a project which simply looked at a unique building detail for my scheme wasn’t an option, the needs for this country are too great, and therefore I aim to prototype a system of building which can be applied to the whole of Cuba.
While initially investigating the idea of resolving construction issues across the country I also came across information which presented vast ecological problems the island is suffering from. It is the combination of these two main issues which I wish to address in Prototyping Architecture:
Morón Sancti Spiritus
01: Creation of Locally Produced Building Materials 02: Ecological improvement of Cuba’s soil quality
Linking these two ideas is my proposal for the introduction of Hemp crops into Cuba’s traditional farming methods. Left: Cuba lies at the mouth of the Gulf of Mexico Above: Sancti Spiritus lies at the centre of the country
While visiting the country in November 2007 we were fortunate enough to gain an understanding of the construction process and the (limited) availability of materials there. What became apparent was the political situation of Cuba within the context of the Western World has resulted in a limit of available building materials; in addition to food, medicines and provisions which is unimaginable to us in Europe. The major effect of this separation was felt with the collapse of the Soviet Union in 1989, resulting in the reduction of building materials, particularly to rural areas far from production centres. With further reading into the procurement process within the communist state I discovered that not only is general provision limited, but when availability of materials increases it is then decided by the government who and where these precious resources are used.
Known for its production of Sugar, Cuban soil has suffered greatly due to 5 centuries of mono-culture sugar cane production. Currently 11 out of the countries 14 provinces (Sancti Spiritus being the capital of one of them) suffers from: corrosion, acidity, salinity and lack of organic material; all due to the intensive production of this one food type. A possible solution to this problem lies in the harvesting and agricultural properties of Hemp cultivation, which if encouraged into a crop rotation cycle could help repair the effect intensive sugar farming has caused, while also delivering a product which has endless applications of different uses throughout the country.
Left: A ‘Machetero’ harvesting the raw sugar cane
The list in order of importance is as follows: 01: Defence
02: Tourism 03: Health Services 04: Education
Right: Industrial Hemp Planting.
Background Identification of problems Last year, The Building and Social Housing Association chose a pioneering project in Cuba as a winner of its ‘World Habitat Awards’. The project, entitled ‘Ecomaterails in Social Housing Projects’, seeked to make ‘buildings more affordable and accessible to local people’. These materials inherently having a low embodied energy, often through the use of recycled waste materials. The aim of their project was to enterprise a local supply system, where materials are produced and sold within local communities and where low energy input and transport issues were added limitations. Reportedly over 2,300 in the Villa Clara province and 5,000 homes nationwide have been built or renovated with the help of this organisation. This fact is important to my project as it shows that the government accepts production of construction materials at a community level and therefore my ideas have a foundation of a precedent which to follow. Within the projects Lime Pozzolana cement was developed (CP-40), this being key to the idea of locally produced materials; cement being available in Cuba, but at a price which local people cannot afford and where delivery of materials is not as reliable as it is here. Following this in September last year, meetings took place in Havana hosted by the United Nations to Combat Desertification and Drought. This continued discussions which identified that nearly 70 percent of cultivable areas on the island was suffering from soil erosion. In less than two centuries Cuba lost eight million hectares of forests. At its lowest point in 1959 only 14 percent of Cuban territory was forested.
The Steko modules I researched achieved a quick build, dry fit construction, based on the principles of toy LEGO. I began to think that proposing a homogeneous block to be a fitting solution, as a moulded shape is surely more akin to LEGO plastic block than separate panels of wood? Visiting Eco Build in London, March 2008 was my first point of contact with Hempcrete. In a brief look at Hemp construction, four alternative applications were available: -Cast In Situ -Spray Application -Panel System -Pre-Cast Hempcrete Blocks (NEW)
Right: In Situ Hempcrete wall with large amount of formwork required Far Right: Spray application, less formwork but high wastage levels
In 2006 the re-conversion of the Cuban sugar industry begun, with the aim to reduce sugar production to a maximum of four million tonnes a year, this it hoped would permit better soil management by farmers. In addition to this, one million hectares of land which were previously dedicated to sugar cane production were to be turned over to produce lumber, fruit orchards, or put to other agricultural uses.
Precedent Ideas: Steko + Hempcrete
Far Left: Modcell Panel System. Cranes are not realistically available in Cuba.
Following research completed for my ‘Housey Housey’ project last semester I wanted to continue my keen interest in the use of fully dry construction processes; mainly as this method of building allows unskilled people to construct a building with very little training and at speed.
Left: Precast block construction. Quick. Low waste. Manageable size.
I wanted to combine the excellent structural solutions of the Steko interlocking block module with the prospect of a quick-growing, organic, ecofriendly material. (Steko blocks are eco-friendly, they are made from the offcuts of engineered timber, something not available as a by-product in Cuba).
Left: A Steko Timber interlocking Module
Right: A Lime technology Precast structural ‘Hempcrete’ Block.
The pre-cast blocks are the result of recent product development with Lime Technologies and BRE at Bath University. Up until this point the ‘green-ness’ of the product had been under question with the need for formwork increasing the cost both in monetary and environmental terms. Spray application carried a large proportion of wastage, and increased training to implement (also using equipment which wouldn’t be available in Cuba). An important item to state in this project is from the outset I have tried to limit my usage of materials and methods of working which would be accessible to Cubans. From my experiences there I have made decisions through the project which have tried to remain true to the restrictions of the people and their day-to-day living conditions and possibilities.
Planning Development of ideas – Cuban / School Environment
The thermal properties of Hempcrete offer attractive benefits. In tropical situations, humidity and passive solar gains within working environments (i.e. schools) lead to uncomfortable and sometimes unbearable working conditions.
Diagram of traditional solid concrete construction and my proposal for a hybrid system, using a structural precast concrete frame with infill panels of non load-bearing pre-cast Hempcrete blocks.
Within the subject of ‘hot and humid environments’ a hot but dry space can still be a comfortable environment. Air saturation in Cuba is frequently high. The traditional solution to this was a heavy insulated roof and light weight walls, allowing air movement throughout the living spaces. The porous nature of Hempcrete naturally draws out excess moisture from its surroundings, lowering humidity levels. Also 250mm of Hempcrete has been shown to completely dampen a sinusoidal change in external temperature of 20° to 0° over a 24 hour cycle (Hemcrete Thermal Blocks).
With the introduction of the hemp blocks the environment of the classrooms will change, compared to if the walls were built out of solid concrete. The panels of infill blocks ‘breath’, allowing moisture to move through the walls, instead of being trapped by concrete. The infill panel also works when looking at the possibility of the expansion of the school. An issue we saw with the current buildings there were problems with adapting the fabric and layout of the existing colonial buildings, to suit the needs of the occupants. As the primary structure is a pre-cast concrete frame the Hempcrete panels can be adapted to change to the needs of the school i.e. removing and extending classrooms by knocking out the Hemp walls, and adding new ones. Additionally the removed Hempcrete can then be combined into the mix to create the new walls Hemp based components. In conclusion to this I aimed to create a prefabricated Hempcrete interlocking block, measuring 300mm thick, based on a clear, simple key section.
Above: Mean, Median and Mode temperatures recorded throughout months in Sancti Spiritus. Average differences of 5 centigrade over the entire month are recorded. Below: Average Temperature and Relative Humidity readings throughout the year in Sancti Spiritus. J
Hemp Cultivation Farming Method - Production As mentioned, Hemp has a multitude of uses, and it is the manner in which it is grown which dictates the final outcome of what materials the plant will be suitable for, this falling into two categories:
300-500 plants /sqm.
Tall, ranging in height from 6 to 16 feet (1.8-4.8 meters). Leaves fall off while growing – replenish soil.
Less than 1% THC (tetrahydrocannabinol)
Used in manufacturing
1-2 plants /sqm.
Short and bushy (no need to fight for sunlight and grow upwards). Promotion of flowering buds.
Over 20% THC (tetrahydrocannabinol)
Used as drugs
Above: The defined separation between the production of illegal and legal hemp products
Growing Hemp within a crop rotational system plays a vital role in organic agriculture. With the industrial production of hemp fibres the requirement for dense growth provides a great deal of shading for the soil conditions, this not only combats the problems of desertification but also restricts the possibility of weeds germinating as their access to light is limited. The leaf debris, a result of the rapid growth of the plant, fall from the plant as it grows, and this alone is the main factor why hemp cultivation could be the key to soil regeneration. During the growth cycle much of the nutrient high leaf matter is returned to the soil. As a crop it needs no chemical herbicides or insecticides, due to the traceable levels of THC which deter animals and insects. Also with this constant shading of the ground there is a lower chance of soil erosion form wind or sudden rainfall (hurricanes are prevalent in Cuba). During the harvesting period, small proportions of the hemp hurd are left behind, below ground. Unlike a conventional crop, where the entire plant is pulled from the earth, only the useful hemp stalk is harvested. The portion of the hemp root is left in the ground and not only acts as a brace, holding the soil together when it is in an exposed state but also acts as a pipe to aerate the ground after the crop harvest. Ideally grown after a winter frost (i.e. In conditions above 0°C) hemp would be a crop very suitable for the climate of Cuba. As see on the previous page the minimum average temperatures for the winter months do not fall below 10°. This would realise the opportunity to create a year cycle production of hemp crops. An average growing time of 120 days (4 months) is required to attain the maturity with which to produce the building quality Hemp shiv. This offers the real chance to create a crop which has annually 3 harvests; running alongside the annual harvest of sugar cane production. This will provide the consistent industry which is currently lacking.
Year 01 01 J
Year 01 02
Year 01 03
D Above: Timeline of hemp crop cultivation. Months blocked in green indicate traditional annual harvest time for Sugar cane, carried out by the ‘Macheretos’ December - May.
Lime technologies Visit Project Initiation – Hemcrete Component Analysis With the research on the previous pages looking into Hemp production I am satisfied with the real prospect that Hemp is a viable crop within the climate of Cuba. In support of this decision, the island of Puerto Rico, 750 miles South East of Cuba, is identified as a major centre of Hemp Cultivation. I have to make assumptions and estimations that the climates of these two countries are relatively similar. I am therefore satisfied this provides a precedent for growth in this region. With my decision on Hemp as the best industrial crop finalised I researched cultivation within England, which lead me to Lime Technologies, based in Oxfordshire. This is the company mentioned earlier which has collaborated with BRE at Bath university to create the structural pre-cast Hempcrete blocks. E-mailing the company and attaching my original project outline, I received an encouraging reply stating ‘Your proposal for the use of Hemcrete is very interesting and potentially very exciting’ this proved enough interest for them to agree to a meeting at their offices where we discussed the project at greater depth.
Tradical HB Hemp Binder prototype
Sprayed panel prototype
Discussing the idea I had for the interlocking block work, and using the object in the formwork image (above right) as an example, I was told I would be able to achieve the same density for my ‘home-made’ pre-cast blocks as occurred in the Hemcrete Thermal blocks (left). The reality is the Cuban people would have minimal access to machinery and I therefore accepted that the ‘hairy’ blocks were more fitting to my project. With their lower density (530 Kg/m3) to the structural block (1120 Kg/m3), they have a lower thermal conductivity, at 0.11 W/m².K compared with 0.36 W/m².K, being more appropriate to the Cuban climate. To clarify; the Mix in England is: Hemp Shiv
Lime Mixture 2.5 Parts Above: The Hemcrete Thermal Block (aka ‘hairy’ blocks).
Water Lime Technologies work in collaboration with Lhoist Uk Ltd (lime manufactures), and Hemcore Ltd (Hemp Shiv suppliers). Lhoist are the largest manufacturers of lime in the world who benefit from many years of continuous lime construction in France. Hemcore are pioneers of re-introduction of hemp growing and industrial processing in England. While at the plant I had 3 basic questions: 01: With the Thermal pre-cast block what was the basic mixture? Basic mix for these were Hemp Shiv (10 parts), Lime mixture (2.5 parts) and water (4 parts). 02: How long do the blocks take to dry? In all, 2 months from casting to dry out. (!)
Hemcrete Structural Blocks
The mix I will be proposing for the use in Cuba: Hemp Shiv
Lime Mixture¹ 2.5 Parts Water
4 Parts (dependent on climate conditions)
¹In this mix the cement binding agent will be replaced by Cuban Sugar Cane Straw Ash (SCSA). See Attached supporting document ‘Lime Pozzolan Binders: An Alternative to OPC?’.
03: What type of cementations binder is used? Reading the fact sheet it is a blend of UK Hydrated Lime (7 parts), Hydraulic lime (1.5 parts) and cement (1.5 parts) The cement amount is very small when considered in the total equation.
I was now ready to begin creating my blocks. Placing an order for a bale of Hemp Shiv, a bag of Hemp Binder and 4 structural blocks I started to organize the formwork.
Formwork Study Limit of materials Over the course of this project I have come up with three scenarios which have become ‘Prototypes’ in themselves and which have almost become more intrinsic to the project than the products they aim to create.
Practically transporting flat packed prefabricated items should involve the minimum amount of components for both costs and efficiency of transport volume for efficient staking etc.
The first scenario I wanted to consider looked at the provision of prefabricated formwork for the use of a farmer to create blocks on-site. This initial method arose from studies of a supplied ‘element’ and the use of that one element to make many pre cast blocks.
Below are several sketches I made while figuring out the best method for the formwork to create a 300 x 200mm volume with which to create the standard cross section for my interlocking block work (see diagram bottom left). A wide and low cross sectioned block, would naturally be more stable.
A A B
In the images above a woman in Anangpur uses a supplied prefabricated metal formwork to produce mud blocks for a wall. Once the mix is compacted into the form the two pins (which hold it together) are drawn out and the brick is released for drying. It is essentially a one person production method. I proceeded to sketch ideas for a flat pack formwork which could be mass produced in Europe and sent to Cuba to provide a standard formwork size.
The design had to be able to create a 300 x 200mm volume, be transported by flat pack and endure ongoing assembly / dismantling to release the block once it had set. 01: Looking at the idea of a base template which to slot wall elements into. Too complicated to produce. 02: Hinged flaps, tied with a hemp rope to provide surrounding formwork. Too many parts to the system, screwdriver for the hinges might not be available to everyone in Cuba. 03: Overlapping edged box, glued. No way of getting the hemp block out of the formwork. 04: Interlocking set of four walls, made up of just two templates, Wall A and Wall B. This proved to be the best solution, as it is basically two template components which could be easily produced in Europe and sent to Cuba. Formwork Assembly and Hemcrete Block Casting: A: Receive Flat Package of Materials (400x430x100mm – smaller than an A2 sheet) B: Layout components F
C: Assemble main walls
D: Position key sections E: Formwork ready: Mix Hempcrete F: Cast Hempcrete block. Once set reverse formwork assembly process to release the hemp block.
C B A
Full scale Formwork Production Formwork Realisation Taking the templates for the formwork I began, in typical Cuban style, to hunt around to make the most of what I could find without buying the items necessary for the job. With the Spring House scrap timber store at my disposal, and plenty of skips in the vicinity I immediately found enough matching sections of ply to serve as my ‘square elements’ and four sheets of medium density fibre board which measured 9mm thick. As the formwork relied on accurate joints for stability I modelled the set in CAD, incorporating the thickness of the mdf before printing out the templates for the formwork.
Above is a simple diagram showing how I arranged the ‘square elements’ within the 300 x 200mm volume to create the interlocking cross section. The position of the pieces is very important, their combined length measuring 300mm and fitting exactly into the formwork length.
Instead of using high-tech solutions to trace the outline of the template on, I used a simple alternative: pins. 01: Lay out the paper template on the mdf sheet. 02: Secure diagonally with two pins at two extreme corners. 03: Work your way round the paper until all corners on the template are pinned through. 04: Remove pins, and paper sheet. 05: With a ruler complete dot-to-dot between pin holes. This also provides greater accuracy as the pencil / pen can be positioned in one pin hole while the ruler is lined up with the destination hole.
In order to create an accurately symmetrical section, the two central pieces are clamped in place while lined up as a set of four. The two loose pieces are then moved to the outer opposite corners, where they will be pushed up against the formwork once the Hempcrete infilling starts. Before all pieces are put in place it was important to lubricate the surfaces of all elements which would be exposed to the drying Hempcrete. Petroleum jelly was used, which acts as a waterproof barrier. Reading into the effects this would have on basic concrete it presented problems with discolouring but as the hemp blocks require a lime render cover to achieve a weather tight construction this aesthetic issue does not present a problem I recognise petroleum jelly is a by-product of the oil industry and it therefore isn’t a long term suitable addition to this highly sustainable product. In the long term I would expect to introduce refined hemp oil (which makes up roughly 30-35% of the plant) to all the the inside faces of the formwork, protecting it in the same way the petroleum based product does. Hemp Oil has is already used in lubricants and paints in the industrial sector. Left: Hand sealing the Formwork prior to mixing Hemcrete
Right, Formwork ready with two clamped central key sections in place and sitting on a raised (ventilated) plinth.
Scenario 01: Courtyard, Spring House / Cuban Farm Scenario 01: People Involved:
1 - 2 Members of a farming family. Has 4 hectares of sugar plantations. 1 hectare of which has very poor soil.
The principle of the idea is based on the fact there is so much poor soil in Cuba from excessive farming that local farmers have a real incentive to pass over a field to Hemp growing; with the knowledge that it is more advantageous to plant hemp than either leaving a field to fallow, being baked daily by the sun, or by growing more nutrient hungry sugar cane. As the lowest yielding field is planted with hemp, the standard four-year sugar production cycle enables the nutrients and soil conditions plenty of time to rejuvenate. As the years pass and further fields become worse the farmer will rotate the crops until all hectares have had a four year period of hemp growth.
Poor soil conditions
With developments in the understanding of the hemp product and its numerous uses, the hemp crop may, at a later stage, become as valuable a crop as sugar cane. If this is ever the case, the proportion of allocated land for each crop would represent this (2016-2020). Location:
Rural. 7 miles from Sancti Spiritus.
1 Hectare (with forecast production of 3 rotations a year). (The field where sugar yield is decreasing due to worsening soil conditions).
3 x 10 tones = 30 tonnes of Hemp (60% of which is Shiv). 18 tonnes of Hemp Shiv (roughly 900 bales) / annum
1 x Prefabricated interlocking Formwork from ARB Rural Studio Solutions
Locally produced components for Lime Mixture.
Gloves for protection when mixing the Hempcrete will be already available within the sugar plantation farm. As will three buckets to mix the Hempcrete.
As the crop develops, so does the farmers living conditions, with the availability of materials enabling the repair and extension of the house. With further investment the creation of an on-site production of the pozzolanic and lime building elements is a possibility (see the ‘house’ development on diagrams below left). On the 22 April my order from lime technologies arrived at Spring House. From this point onwards I was carrying out a ‘method acting role’ of this Cuban farmer who had harvested his first hemp crop and with the free formwork received from ‘ARB Rural Studio Solutions’ was trialling his new crop in Hempcrete production.
Once the Hemp is introduced it will work on a 4 year cycle dictated by traditional Sugar cane production. Block drying to take place under shaded tree area to the South of the house. Nearby water allows for onsite retting of hemp downstream. Farmer Aspiration:
Wants the chance to repair his home without problems and transport costs involved in obtaining materials from the nearest city (Sancti Spiritus).
Farms 4 year Plan:
¼ Hemp production, with Hempcrete block production 3x a year. ¾ Sugar production with annual harvest.
H S S S Left: Receipt of delivery (not very Cuban) Above left and right: The delivery at Springhouse.
Scenario 01: Hempcrete Mixing / Casting I was now a Cuban farmer, and as a result I had no access to rotary drum mixers, precise measuring equipment, even a hose for water (my ‘nearby lake’ was in fact the Spring House Canteen tap – the bucket wouldn’t fit under the taps in the toilets) The mix I will be using: Hemp Shiv Lime Mixture Water
10 Parts 2.5 Parts 4 Parts (dependent on climate conditions)
It is worth mentioning here that the exact mixture of materials depends to a certain extent on the climate where they are to be used and the method of application. As the climate I was working in was damp and cool, the amount of water I used was a little below that of the ratios stated above. Here is the area of the courtyard I occupied for the time I spent producing the Hemcrete. 01: Lime Mixture. 02: Hemp Shiv bale. 03: Bucket (one found by the road). 04: Formwork. 05: Local rocks (prototype from pervious years). As I am a farmer working on my own, the ratios will have to represent the amount I could feasibly mix and which the bucket could accommodate.
Above: Measuring out the 10 Parts of Hemp Shiv.
Almost immediately I realised what a huge amount of effort creating just one block would take. The volume of the formwork to produce a 350mm long block was 0.01575m3 , but this required three 5 litre buckets of mixed Hemcrete! Mixing the product on your own and without mechanical aid is a nightmare. A big problem I found was the fine lime binder sits in clumps at the bottom of the bucket, and fixes with the water while the larger hemp shiv particles sit on the top level almost completely dry. To combat this, and the possibility of not creating an even coating of lime mixture on all the hemp shiv, I began using another bucket. The mixture was then moved from one bucket, being tipped upside-down, back and forth until all the shiv was sufficiently covered.
A simple plastic beaker was used, which provided my constant volume with which to measure out the components into the bucket.
At this stage the requirement for an extra bucket came apparent, as I needed one to carry water from the lake and one to mix the Hempcrete in.
The process of measuring began, first adding the hemp, then the lime mix then the water.
IMPORTANT: Once the lime mixture is being used it is important to wear tough gloves and clothing to prevent the lime resting on the skin, as this will (it did) lead to a lime burn as a result of lime being trapped and rubbed between your skin and clothing.
Above: Hand mixing and transferring between two buckets to achieve shiv with the correct lime binder coverage.
The entire process of mixing enough product for just one block took over 2 hours. Once I had the system set up my a bucket of 5 litres took 15 minutes to mix. Despite this, in a constant production a single farmer could not hope to achieve any more than 1 block every 45 minutes.
Scenario 01: Hempcrete Mixing / Casting
Releasing the Block
The final mix was then placed into the mould, where I compacted it to achieve a density similar to the Thermal Hemcrete Block. This was done by simply pushing the mixture down into the mould.
Despite this conclusion, one week on from casting the block, and with the 1 exposed surface dry, I decided to release the formwork and see whether the mixture had allowed me to create an accurate cross sectioned block without the aid of high-tech machinery.
Above: Initial removal of weather proofing. See the ‘local rocks’ used to lift the lid off the formwork to provide ventilation.
Summery of my thoughts at this point: 01: This is a ridiculous method of producing the blocks. Not only does the formwork take a long period to fill with enough Hempcrete but the setting time is 60 days per block. 02: Considering this, the mix also needs to remain within the formwork for a minimum of a week to achieve the precise cross section, enabling the blocks to interlock. 03: As the formwork is possibly the most eco-unfriendly element of the whole project so far, it is absurd to use one thing, with all this embodied energy (air freight to Cuba etc.) and then only be able to use it once a week.
I began with positioning the mould diagonally on the plinth, I focusing my attention to removing one of the smaller panels, as this would have less surface area and therefore less surface friction with the cast block. Once one of the sides was released I envisaged the ‘ridged’ nature of the rectangle would open up slightly to release the blocks three remaining surfaces. Combining the positioning of the mould on a diagonal with the interlocking nature of the formwork allowed for this one panel to be removed while the Hempcrete block was still fully supported.
04: The week setting time also rules out the chance of mixing a large amount of Hempcrete at one time. As by the time the formwork is again available the mixture for the next block would have set in the buckets). Casting this block made me re-asses the original ideas behind this project. The case studies I referenced at the research stage were designed for many people to co-operate into the production of materials. The key to proposals of this nature of production is the old saying ‘Many hands make light work’. I believe in the suitability and possibility of the Hempcrete blocks. It is not the basic idea which has failed here, simply the first method I presented as a production technique. Taking these thoughts I analysed the samples I bought from Lime Technologies. The realisation hit me that my assumption of pre-cast blocks of Hempcrete was incorrect and had instead followed that of precast concrete, where a formwork is filled off site, emptied and re-used. With these ‘pre-cast’ blocks they are instead pressure cast in a mould, then set to air dry. Above: My prototype after it’s week setting in the courtyard.
Method explained: 01: Diagonal Positioning. 02: Demonstration of section which will be hammered out (in a downwards direction). 03: Quick test to ensure mould has not cast onto formwork. 04: Hammer the formwork panel down to release block. The parts of the formwork to hammer on were the two end pieces (where I’m holding on image 02) as this prevents damage to the shape of the block.
Scenario 01: Releasing the Block continued
Efficient Air Drying
Once the initial panel had been fully detached the rest of the formwork, as anticipated, pulled away form the block with very little resistance.
Once the block had been released it was apparent that the sides were still quite damp (though it was difficult to be certain to what extent as there was also the petroleum jelly in places). Considering the need for air drying is still something which will effect the project (see later scenarios) and I therefore wanted to come up with the most effective and area efficient methods of arrangement which would a) maximise the surface area to convection currents, b) reduce any unnecessary pressure on the blocks while they dry in the required shape, and c) maximise floor area usage. With little thought needed the best position to achieve minimum ground coverage was the orientation chosen for the casting. This also abolished any uneven loadings on the cross section while the Hempcrete was setting. 01: This position puts undue compressive strain on both the ‘feet’ leading to potential buckling. Possible shear stressed on the recess. 02: Here the positive interconnecting section could be subjected to compressive flattening over the two months. Possibility that the two ‘arms’ could deform.
The next step of the process was releasing the four solid key sections which the block had been cast around. Being enclosed on three sides the central sections, forming the underside of the block, presented a challenge; to remove them while limiting damage to the cast block. The solution was to simply give them each a good hard whack with the hammer, to agitate the surface between the two components, then knock the solid pieces away and out of the block. Following this same principle the corner sections just dropped away from the block.
Considering the densities achieved with this method and orientation of drying lead me to studies in their arrangement: A: Maximum density, with 75mm gaps between blocks for air circulation. Here the blocks would be staked, filing the space, then be left to dry. The process of removal would then take place in the reverse direction. The density here is 0.092 block/m³.
Though this is a very dense arrangement I see the benefit in adding routes between the blocks, as this not only facilitates observation but also am concerned that the drying process may be effected if densities for drying are too high (humidity in Cuba).
B: Here the blocks are arranged so positioning and removal can take place on either side of a 600mm wide access route. The density here is 0.13 block/m³.
06 – Block cast, this one block will be ready July 2008.
Blocks can also be monitored to check consistent drying through the batch (doing random selection from different rows and testing them for strength / interlocking qualities). Therefore, through analysis minimising drying times and maximising production. Scenario 2 takes this and applies it to a community production level.
1:2 Scale Construction Model Multi block construction With the realisation that I would only been able to make one full scale block I began looking into opportunities I had to construct a working model of the system to show the incorporation of the structural qualities and elements of the precedent ‘Steko Module’. When placing the order with Lime Technologies I had planned ahead. Even if I had started production on the first day of the Prototyping Architecture course I would only have ever had made a maximum of 2 blocks ready for construction for the presentation. As an alternative I looked at using the pre-cast Lime technologies Structural Hempcrete Blocks. Using these would allow me to build a 1:2 scale model of the structural system, which I would use to demonstrate the ease of building with the blocks. Here I look at and document the making of these scaled blocks, before aiming the project in a more theoretical direction with the different scenarios of production. Once the blocks were carved the tie element of the Steko module (in Switzerland it is a steel rod) needed to link the blocks together.
Above: Original Pre-cast Block hand sawn into 1:2 interlocking cross section blocks. Below: Diagram of wall showing section and channels created by the holes. This method of construction also minimises mistakes onsite, as the blocks have to fit on the grid of shiv stalks. The holes would be incorporated into the modified CINVA Ram design for consistency (see next page), increasing accuracy of the build further.
My Cuban solution uses un-processed Hemp Shiv, which, as mentioned, grows very straight and very long (up to 4.8m). These would be bundled into groups of three and the blocks pushed down onto them. Insect inhabitation was something which concerned me, as in this case the Hemp Shiv is left bare, it is not Hempcrete. As mentioned earlier the characteristics of why the crop grows with no pesticides, I discovered , is due to the narcotic element (THC) within the hemp rendering it inedible to pests. Taking the structural idea further I also considered an addition to the method to increase structural stability. Instead, using just one hemp stalk in each series of holes. Throughout the building of the wall the 50mm ⌀ holes would then be filled with a lime/pozzolana mix at intermediate levels (every 2/3 courses). This would stiffen the whole panel while still offering the flexibility in fabric structure mentioned when looking at future adaptation needs (knocking out walls etc.).
When studying the Steko module in Semester 1, there were several questions I had as to how it was constructed. This was partially due to the language barrier (almost all information was in German) but also that it was a process of construction which I wasn’t familiar with. After the submission I finally got through the post what I had been waiting for: a set of three CD’s with short videos on each showing the construction process for different projects. This immediately gave me a clear understanding of the way the walls were built. Naturally very few households in Cuba would have the provision of a computer to watch something similar, but with cinemas in the country being extremely popular the message of self build could be conveyed to a mass and (possibly more exciting) a younger audience of enterprising ‘grow-it-and-do-it-yourself’ Cubans.
Scenario 02: Cuban Community Co-operative Scenario 02: People Involved:
12 Members of 6 different farming family within a community. Have 24 hectares of sugar plantations. 6 hectare of which has very poor soil.
Location: Hemp Planted:
Right: Community Workers with a CINVA Ram
Hemp Produced: Provided items:
Far Right: Wider Context of Community
Bought Items: Assumptions: 02
Community Aspiration: 06
Community 4 year Plan: 05
Semi-Rural. Community off the main road, equidistant between the city of Sancti Spiritus to the South and town of Guayos to the North. 6 Hectares (with forecast production of 3 rotations a year). (The fields where sugar yield is decreasing due to worsening soil conditions) 18 x 10 tones = 180 tonnes of Hemp (60% of which is Shiv). 108 tonnes of Hemp Shiv (roughly 5,400 bales) / annum. 1 x CINVA Ram compressive block work making machine, modified to created key cross section blocks. (trade cost of £400 – provided with grant from ARB Rural Studio Solutions) Possibly 1 x mechanical mixer. If not, then mixed by groups of people. Locally produced components for Lime Mixture OR see key 06, bottom left. Gloves for protection when mixing the Hempcrete will be already available within the sugar plantation farm. Once the Hemp is introduced it will work on a 4 year cycle dictated by traditional Sugar cane production. Block production and drying to take place within existing shed structure. Wish to produce enough blocks to build a primary school for community children within a year using local workmanship. Create a co-operative within the community for future building works. ¼ hemp production, with Hempcrete block production throughout the year. ¾ sugar production with annual harvest.
CINVA Ram Technology: 04
While at the CAT centre in Wales a group experimented with straw and clay blocks in a human powered compressive machine called a CINVA ram, producing standard rectangular blocks. Unfortunately we visited before my ‘epiphany’ at Eco Build with the discovery of Hempcrete but I still witnessed and understood the principles of the machine and was impressed by the teams ability to produce a vast number of blocks very quickly and with very little guidance. With the experience of ‘Scenario 1’ I began researching the uses of CINVA rams and revealed production rates for blocks to fall in the range of 200-500 blocks per day. Further studies showed the modification of the basic volume in some models to create structural interlocking blocks.
07 03 03
01: Main Road between Sancti Spiritus (4miles South) and Guayos (4 miles North). 02: River section for Hemp retting. 03: Poor quality farm land (6 Hectares) proposed for Hemp cultivation. 04: Households. 05: Central production shed for CINVA Ram block production and block drying. 06: Possible conversion of redundant buildings to simple furnaces to create pozzolanic element from Sugar Cane Straw Ash (SCSA). 07: Location of New Primary School within community. (Currently nearest school is 4 miles north or south)
With the change of production method I would expect the ratios of the mixture to alter: possibly containing less water and more cementitious material to create a more stable consistency? I considered this while thinking about the questions I asked at LT, when referring to their blocks and the combinations stated. In principle, the blocks I am proposing now, using the CINVA ram, are truer to the LT thermal blocks than the single block made without compression in the formwork. The ratios should, therefore, require no change. Unfortunately, despite my ongoing search for a CINVA ram machine in London I was unable to locate one. From my observations at the CAT centre, and in discussions with Josh Williams (Unit 1) who was involved in the team which used the mechanism, their group of 4 produced a total of 64 blocks on the first day. This was while testing ratios of straw to mud therefore not really maximising on production. On the following page I aim to propose this method of Hemp and block production within the community.
Scenario 02: Hempcrete mix:
Cuban Community Co-operative A
Farming Method. Consulting the timeline for hemp cultivation I have defined the growth and harvest pattern the 6 farms would have to follow in order to create a constant production of hemp blocks throughout the year. This process of production is restricted and dictated by the limit of space the community may have concerning the storage of the blocks for the 2 month drying period within the production shed (see table below).
80% of mix
Density of Block
Volume of Block
Weight of Block
Of which Hemp Shiv
1 hectare of Hemp
6 Tonnes of Shiv
As the demand from the community (and possibly surrounding villages and towns) grows more hectares of land can be planted, but this proportional increase would have to factor also to the size of the drying area. E
Here the farms follow a pattern of crop cultivation. As a co-operative organisation the machinery involved in the process only needs to be used in one place at one time, reducing redundancy.
To the far left is a calculation of the quantity of blocks achievable within the year.
FARM A J
6,000 kg Shiv
900 Blocks (3 days work & 117mÂ˛ drying area)
In reference to this amount my school requires 14,781 Hempcrete blocks.
Catering for 190 students this is a large school building and provides a crude estimate of 78 blocks/person. The population of the school for this particular semi-rural community may reach 20-30 including teachers, therefore requiring 2,333 blocks, well within the annual predicted amount. Left: With the focus on block making within the co-operative the farmers would be contractually expected to give back to the community project their first hemp crop. Once this requirement is fulfilled there could be the opportunity to use the next two harvests of the year as they wish. Further collaboration between the farms may then branch out into the multitude of other possibilities Hemp has to offer.
Scenario 03: Maximise the potential in typical Cuban style – reuse of whatever’s ‘lying around’ Further development. In Cuba they have the old saying ”Sin azúcar no hay País” – “without sugar there’s no country”. This is indeed a fair statement, as introduced to the country 500 years ago, this one crop has shaped Cuba economically, socially and politically. No period of history has moulded the Cuba of today more than the last 100 years. Economic and structural indifference between the west and east (main sugar production focused near Havana in the west) in the late 19th century resulted in The Ten Years War; ended in 1899 with the intervention by America on the island. From this point the Spanish – American war began which weakened the Cuban sugar industry (and with it the main portion of the countries economy) to the point of venerability; clearing a way for a foreign takeover. This is effectively what happened when the US established a ‘stranglehold’ over the island at the turn of the last century. Cuba began the twentieth century under ‘indirect’ American control, under the dictation of the Platt Amendment, this stating that “the USA had the right to intervene in Cuban affairs should the independence of the country come under threat”. It was in this period where the illegal occupation of Guantánamo bay with a US navel base began. In 1902 the first president of Cuba, Tomas Estrada Palma was elected as the first of a long line of political puppets under predominant US control. With the economy in ruins following the war, opportunistic US investors were able to buy large stakes of land for sugar production relatively cheaply. Soon three quarters of the sugar industry was controlled by US interests. With this came modernisation of the Sugar production process, with huge factories known as centrales processing sugar cane from hundreds of surrounding plantations. By 1956 there were 161 mills on the island, with over half of them being run, and making profit for, foreign investment. This was one of the main factors Fidel Castro’s nationalist revolutionary followers had issue with and, unsurprisingly, one of the first acts of the new revolutionary government was nationalize the entire industry in 1960. Ten years into the new government Cuba’s economic dependency on sugar was under question, following the unrealistic aspirations set by Castro for the production of 10 million tonnes. In the late 1970s the government made the first steps to diversify the economy. Unfortunately relying on one thing has always been problematic to the Cuban economy and, as mentioned in the introduction to this project, the Soviet Bloc collapse of 1989 (on whom Cuba’s financial situation practically depended on) wiped out 80 per cent of Cuba’s trading wealth. Following this, the government sort to once again diversify the economy. Tourism, though initially strongly rejected by the Revolutionist, was adopted for this role. In 2002, following the success of the tourism industry the government issued a plan to close almost half of the sugar mills (roughly 80 factories) to increase the remaining factories efficiency and productivity. Recent figures show desired cultivation rates (50 tonnes a hectare) well over those of actual production: 35 tonnes / hectare. Combining the research and development I have prepared into the cultivation of hemp, and the Cuban mind set of never letting anything go to waste my third scenario combines the possibility of Cuba becoming one of the largest Hemp production manufactures in the world. The poetic justice here is too great an opportunity to miss: Cuba making money on a crop once internationally declared as illegal by the USA, as it threatened their interests in oil production and petrochemical uses; whilst using machinery and factories built by the USA.
Following and whilst considering this, as also mentioned in the introduction to the project: In 2006 the re-conversion of the Cuban sugar industry begun, with the aim to reduce sugar production to a maximum of four million tonnes a year, this it hoped would permit better soil management by farmers. In addition to this, one million hectares of land which were previously dedicated to sugar cane production were to be turned over to produce lumber, fruit orchards, or put to other agricultural uses. This could be the opportunity for Hemp production to be realised. By just taking a third of the 1 million hectares put Cuba could still produce 6 million tonnes of Hemp / annum. The sugar mills themselves have great potential. Intrinsically linked into the country each one has excellent existing infrastructure, once making full use of the train network (the only one operating in the Caribbean) transporting processed sugar from the country to the cites and ports. With 80 factories across Cuba now redundant from the economic reform of 2002 and a lack of goods still due to the ongoing USA embargo the crop with ‘A Million Possibilities’ could really make a difference to health, nutrition, the economy and not forgetting, Cuba’s soil conditions and the countries future construction possibilities.
Over the following pages I have schematically looked at a disused sugar mill on the outskirts of the town of Morón, 54 miles East of Sancti Spiritus and 250 miles from Havana. See Cuba map on introduction page. Below: Photos of the abandoned site:
Scenario 03: MorĂłn Sugar Factory â€“ Existing Building Identification
01: Delivery Area 02: Furnace
03: Local Sugar Cane Delivery 04: Cane Process 05: Cane Process 06: Liquid Extraction
07: Covered, Ventilated storage for sugar drying
08: Low grade Industry 09: Offices Administration
10: Train arrival 11: Train dispatch 12: Local road collection
13: Water tanks
Scenario 03: MorĂłn Hempcrete Factory â€“ Proposed Area Allocation
01: Retting Area (pools) 02: Sugar Cane Straw (Bagasse) Boifuel Furnace
03: Lime and Pozzolana production (made from SCSA Sugar Cane Straw Ash) 04: Hemp Shiv Extraction
05: Hempcrete Mixers 10
06: Compression Machines
07: Covered, Ventilated storage for 2 month drying period
08: On-site textile workshop 09: Shop
10: Train arrival
11: Train dispatch 12: Local road collection 13: Water tanks 01
Cinva Ram Technology:
Allin, Steve (ed.) 2005: Building with Hemp. Seed Press
Weinhuber, Karl 2003: Wall Building Technical Brief: Building with Interlocking Blocks http://basin.info/gate/interlocking.htm accessed on 02/05/08
McAuslan, Fiona / Norman, Matt (ed.) 2007: The Rough Guide to Cuba. Rough Guide Publications
Williams, Joshua 2008: Wales Diary.
News sheet, CINVA Ram fact sheet and costs for CINVA Ram found on: http://www.parryassociates.com/ accessed on 02/05/2008
CP-40: Lime Pozzolana Cement Replacements:
www.hempbuilding.com www.limetechnologies.co.uk www.greenerbuildings.com www.bre.co.uk
B. Middendorf, J.F. Martirena, M. Gehrke and R. L. Day 2005: LIME POZZOLAN BINDERS: AN ALTERNITIVE TO OPC? International Building Lime Symposium Orlando, Florida http://www.nationallime.org/IBLS05Papers/Middendorf_Pozzolan.pdf accessed on 02/05/08
Specific Web Pages: Cuban Conditions:
J. F. Martirena, P. Seijo, S. Kennas, I. Machado, R. Gonzales 2002: WASTE TO ENERGY. TECHNOLOGIES TARGETING THE POOR. THE CUBA CASE STUDY. World Renewable Energy Congress. Koeln, June-July 2002 http://www.bioenergylists.org/stovesdoc/Martirena/WREC.pdf accessed on 02/05/08
Grogg, Patricia 2007: Accents: Sugar Cane Culprit in Cuban Soil Depletion. http://www.tierramerica.net/english/2003/0825/iacentos2.shtml accessed on 14/03/2008
Also with thanks to the following:
Martirena, Dr Fernando 2001: Housing Renovation as Part of a Post Hurricane Response Programme. http://www.devalt.org/newsletter/may01/of-1.htm accessed on 18/03/2008 Frank, Mark 2007: Cuba scrambles as sugar harvest drags amid rain, heat. http://uk.reuters.com/articalPrint?articalId=UKN2628540520070226 accessed on 03/05/2008 Barclay, Eliza 2007: Building Green and Local In Cuba. http://www.treehugger.com/files/2007/09/cuban_ecomaterials.php accessed on 14/03/2008 Google 2007: Cuban Transport Guide: Trains in Cuba http://www.kwintessentail.co.uk/articals/artical/Cuba/Cuban-transpot-guide:-Trains-in_Cuba.html accessed on 03/05/2008
Hemp Cultivation & Facts: Moran, Carolyn 2007: A Treefree Botanical of Plant Fibres http://www.whotheearth.com/issue/90/artical/8/9.treefree.botanical.of.plant.fibers.htlm accessed on 02/05/2008 Wikipedia 2008: Bagasse http://en.wikepedia.org.wiki/Bagasse accessed on 02/05/2008 Bunn, Roderic 2007: Grow your own insulation http://www.bdonline.co.uk/story/asp?sectioncode=453&STORYCODE=3086670.html accessed on 02/05/2008 Pierre & Gino: Troubled Times http://www.zetatalk.com/shelter/tshlx029.htm accessed on 02/05/2008
University of Portsmouth (Thanks for dragging me to the Hemp stand at EcoBuild)
London Metropolitan University (Unit 1)
James and Chris
London Metropolitan University (Spring House Workshop)
Centro Meterological Provincial Sancti Spiritus
4TH Year Report, looking at the real viability of Hemp production in Cuba, offering a locally produced building material, with the ecologic...