ISSUE TWO • 2018
THE CMA – QUALITY CAST IN CONCRETE
• World beating block maker • 3D printed house • Excellence on display
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WORLD-BEATING BRICK, BLOCK AND PAVING PLANT – MADE IN SA
30 PREVENTATIVE MAINTENANCE ENSURES DURABILIT Y
28 ADMIXTURES ROLE IN MEETING STRICT REQUIREMENTS FOR CONCRETE
17 NEW AGGREGATE HAS EXCITING POTENTIAL FOR PRECAST
31 ADVANTAGES OF PRECAST CONCRETE WINGWALL UNITS
AROUND & ABOUT
CMA PUNTS QUALIT Y CONCRETE TO AVOID FAILURES
CEMENT PRODUCER SUPPORTS PRECAST INDUSTRY
32 WEIGHT COLLARS FOR DESALINATION PLANTS
TRAINING ON JBCC BUILDING CONTRACTS
33 AFRICA’S MOST SOUTHERLY ROAD PAVED WITH EXPOSED AGGREGATE CBP
10 HONORARY LIFE MEMBERSHIP FOR FLOORING DOYEN
10 ALL SYSTEMS GO FOR INDUSTRIES TCC 2018 11 EXECUTIVE DIRECTOR RETIRES 12 REGIONAL MEETING WILL HELP DETERMINE CMA PATH 13 YEAR AT A GLANCE AT WC REGIONALS
COMPANY NEWS 14 MANUFACTURER SUPPORTS EDUCATION
14 PRECAST is the mouthpiece for the Concrete Manufacturers’ Association - CMA Concrete Manufacturers’ Association Physical Address: Office 0400, Standard Plaza Building, 440 Hilda St, Hatfield, Pretoria Postal Address: Post Net Suite 334 Private Bag X 15, Menlo Park, 0102 Tel: (+27 11) 805 6742 Fax: (+27) 86 524 9216 E-mail: email@example.com Website: www.cma.org.za Publishers: Isikhova Publishing & Communications Postal Address: PO Box 651793, Benmore, 2010, South Africa Tel: (+27 11) 883 4627 Fax: (+27 11) 783 2677 Website: www.isikhova.co.za Publisher: Andrew Meyer Tel: (+27 11) 883 4627 E-mail: firstname.lastname@example.org Consulting editor: Raymond Campling Tel: 076 297 2775 E-mail: email@example.com
PRECAST | ISSUE TWO | 2018
20 TOP ARCHITECTURE STUDENT AWARDED FOR NEW DISTRICT SIX VISION 21 BFT INTERNATIONAL EDITOR VISITS CAPE CAST STONE MANUFACTURER
34 DIVERSE PROJECTS FOR PIPE MANUFACTURER 37 NEW 3D PRINTED HOUSE 38 PERMEABLE GRASS BLOCKS USED FOR MASSIVE STORMWATER CHANNEL 39 CONCRETE CAST STONE COBBLES – UPGRADE WINE ESTATE HOUSE
AVOIDING FAILURES IN THE INSTALLATION OF CONCRETE BLOCK PAVING ON CONCRETE ROOF DECKS
26 SOUND PRACTICE CAN EXTEND CONCRETE DURABILIT Y 27 GLOBAL EXPERTS PRESENT PIGMENT SEMINARS
42 SA’S SMART CITIES ARE DRIVING SUSTAINABILIT Y
Coastal editorial: David Beer Tel: 082 880 6726 E-mail: firstname.lastname@example.org
ISSUE TWO • 2018
THE CMA – QUALITY CAST IN CONCRETE
Advertising: Wally Armstrong Cell: 083 701 3278 E-mail: email@example.com Subscriptions/Accounts: Thuli Majola Tel: (+27 11) 883 4627 E-mail: firstname.lastname@example.org Design and layout: Joanne Brook E-mail: email@example.com The views and statements expressed in this publication are not necessarily those of the editor or the publishers and neither the publishers nor the CMA accept responsibility for them. No person connected with the publication of this journal will be liable for any loss or damage sustained as a result of action following any statements or opinions expressed herein. The same applies to all advertising. Precast© 2018. All rights reserved. No part of this magazine may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage retrieval system, without prior written permission from the publishers.
16 PRECAST MANUFACTURER CONDUCTS SUSTAINABILIT Y STUDIES FOR PROJECTS
• World beating block maker • 3D printed house • Excellence on display
ON THE COVER PMSA has developed the world-beating PMSA Ultra 3000 brick and block manufacturing plant which is 100% focused on meeting high volume manufacturer’s requirements for superior quality products and out-perform their opposition in fiercely competitive market spaces. Its engineering genius allows it to operate rapidly, change setups and machine parameters to produce multiple different products per customer requirements.
COVER STORY 3
The PMSA Ultra range brick, block and paving machine is 100% focused on meeting high-volume manufacturers’ r e quir em e n t s f o r sup e r i o r - qu ali t y products to out-perform opposition in fiercely competitive market spaces. Simultaneously, its engineering genius allows its operators to rapidly change set-ups and machine parameters in order to produce multiple different products that will meet customers’ requirements. Thanks to the massive volumes the machine is able to produce, this ability effectively gives manufacturers the
BLOCK AND PAVING PLANT
MADE IN SA
Home-grown technologies developed by PMSA engineers to meet the challenging and demanding requirements of concrete manufacturers over the years are part of the blueprint used by the company to develop its world-beating PMSA Ultra 3000 brick and block manufacturing plant.
scope to manufacture volumes of products such as bricks in the morning and
(Above): PMSA launching the Ultra 3000 at Bauma Africa March 2018.
seamlessly switch to kerbstone, paving
(Left): The feedbox is heavy-duty and guided in closed rails for more accurate feeding and filling of the mould box.
or any other product later in the day, or to effectively become a just-in-time manufacturer. This combination of speed and versatility enables it to do the work
Built to last
of two or more machines, which can dra-
This is echoed by PMSA sales and mar-
matically reduce labour costs, storage
keting manager Quintin Booysen, who
and other requirements.
adds that the Ultra 3000 is an ideal solution for large-scale suppliers with
Experience to bear
diverse product requirements. Like its
PMSA managing director Walter Ebeling
namesake, and derived from its engi-
say s the same design genius also
neering brief, the new plant is designed
ensures that the PMSA Ultra 3000
to be ultra-fast, productive, reliable, efficient, easy to use and able to produce
will last longer and require considerably less maintenance than other types of
3000 has been developed with a rigid
machines. “It’s designed to run two or
frame that absorbs most of the vibration
the best-quality products available. “We started the design process with
three shift operations per day and night
energy and shock during operation and
the main moving parts and designed the
and is so fast that it’s actually forced
can therefore replace almost any old-
mould and tamper assemblies in a way
us to redesign packaging and product
technology plant on existing foundations
that eliminates movement as far as
handling systems to match the output
and immediately start making more and
possible,” he explains. “As a result, it’s
of the Ultra 3000 block machine.
better products faster.
centred on four large 120mm diameter
“Based on its output and quality, as
“Being fully designed and built right here
chrome shafts to prevent back-to-front
well as the wide range of product types
in SA, the 30-ton block machine delivers
or side-to-side movement. The mould
that it can produce, we feel it’s going to
unsurpassed value-for-money for a ma-
assemblies are then firmly clamped to the
change the game completely. Best of all,
chine that we believe is the best of its type
shaft, rather than sliding down over fixed
despite its imposing size, the PMSA Ultra
in the world at this time,” says Ebeling.
shafts, so that when the mould’s lifted,
PRECAST | ISSUE TWO | 2018
IF YOU THINK PRECAST CONCRETE,
THINK CMA PRODUCER MEMBERS.
AT I O N
y c a s t in c o
Address: Office 0400, Standard Plaza Building, 440 Hilda Street, Hatfield, Pretoria, 0083 Tel: (011) 805 6742 • Email: firstname.lastname@example.org • Website: www.cma.org.za
concerns downstream in the manufactur-
“In order to account for the speed of
mould box and tampers being supported
ing process. The concrete silo draw is
operation and power of the machines,
in this new manner. The tampers have
run by a gearbox and variable speed drive
the hydraulics also make use of two large
additional bushings to further eliminate
which is fast and reliable, combined with
accumulators to store hydraulics under
movement on the shafts.
laser level filling control in the feedbox for
pressure and ensure hydraulic power’s
accurate and consistent filling.
always available during the demanding quick
“Furthermore, the heavyweight, rigid frame is designed to fully absorb shock and
cycle times of the machine. The pumps are
vibration without allowing movements to
Built for speed
also separate from all other systems to
transfer to the operational components
“In order to support the super-fast
ensure cooler operation. Coupled to the
of the machine. This not only ensures
cycle times of PMSA’s Ultra 3000, the
plant’s world-leading PLC control systems
higher-quality products, but reduces
hydraulics and peripheral supply systems
that link vibration, hydraulics and elec-
wear and tear, with obvious benefits for
are designed to be fast and efficient. The
tronic systems, the system provides the
the longevity of the equipment.
hydraulic system, for example, is designed
fastest possible and most accurate cycles
to be uncluttered with a separate valve
that are infinitely repeatable.
Vibration and filling
stand for accessibility. By moving it off the
“And, to complete the picture and
“Aside from its precise construction, our
block machine, it’s unaffected by move-
cater for the large volumes of products
new machine also makes use of our ultra-
ments and vibrations which could disrupt
manufactured, the PMSA Ultra 3000
efficient UltraVibe technology, which
the system over time. It also uses flexible
makes use of over sized 3 000- to
enables the operator to select the exact
hydraulic pipes back to the machine to
3 700-litre planetary mixers, depending
vibration force, vibration frequency
limit any movement on the valve stand.
on the type and size of end products
and amplitude required per product
being manufactured,” says Booysen.
type. T his unique vibratory system allows variation of force and frequency
independently from each other, which
The Ultra 3000 is designed for the
can be delivered instantaneously to
manufacture of 60 interlocking pavers
provide faster and more optimum filling
per drop, or 30 hollow blocks 390 x 190
of concrete in the moulds.
x 140mm, 21 hollow blocks 390 x 190
“Considering that it can make prod-
x 190 mm, 44 maxi-bricks 290 x 90 x
ucts of 25mm-500mm, it stands to
140mm, 78 stock bricks 210mm long or
reason that the vibration system needs
189 rectangular pavers, 91 maxi and 144
to be infinitely programmable. For dura-
stock bricks on end per drop.
bility, the heavy-duty vibrators are sealed oil bath types requiring no maintenance.
Coupled with the PMSA new filling mecha-
In summar y, Ebeling say s the new
nism and precision tamper, the system’s
PMSA Ultra 3000 machines are the
able to maintain unmatched cycle time
culmination of all the company’s decades
on large 1,4 x 1,1m production boards.
of experience and engineering abilities. It
“Its feedbox in-rail design ensures the
has been designed to be the best of its
feedbox runs straight and true in every
class in the world and operate reliably
cycle, with no possibility of movement
and efficiently to meet the demands of
resulting in under- or over-filling of a mould
which can result in end-product size vari-
Its rigid and precise construction
ations. A hydraulic agitator also ensures
makes it ideal for continuous operation
even coverage between the front and back of the mould to achieve correct filling of the mould cavities. This reduces shortfilling and associated quality and packaging
(Above, from top): Simple touch-screen operation changes parameters on the Ultra 3000 instantly; the Ultra 3000 sports a heavy-duty, overdesigned frame for longevity and containing the machine vibration within the machine frame to reduce wear and tear, as well as maintenance costs.
throughout the year and is backed up by PMSA’s unsurpassed af ter-sales service throughout the entire region and globally.
Interlocking pavers with topping feed
Hollow blocks 140mm width
Hollow blocks 190mm width
Pavers on end
Maxi on end
Bricks on end
Kerbstones 1 000 x 300mm
Number of products per drop
9 hours production (approx)
Boards per 9 hours (approx)
PRECAST | ISSUE TWO | 2018
it’s even and very precise due to the
EIRICH R-TYPE MIXERS + HYDRONIX MOISTURE CONTROL = TOTALLY CONSISTENT CONCRETE WITH EVERY BATCH
HYDRO CONTROLAUTOMATES MIXING A. BATCH IN MIXER B. CEMENT DISCHARGE BY TIMER C. MONITORED FLAT LINE FOR DRY MIX AND MOISTURE MEASUREMENT D. WATER DISCHARGE E. MONITORED FLAT LINE FOR WET MIX F. TIMED DISCHARGE
COST SAVINGS WITH EIRICH RV19 INTENSIVE MIXER SAVINGS IN CEMENT, PIGMENTS, ENERGY, WATER AND REJECT RATES HAVE BEEN REPORTED FOR 30 YEARS. PRECISE BLENDING AND HOMOGENOUS MIXES ARE ACHIEVED WITH SHORT MIXING TIMES. CONCRETE QUALITY AND SURFACE FINISH SPECIFICATIONS RISE CONTINUOUSLY. THE EIRICH R-TYPE MIXER IS BEST SUITED TO THIS DEMANDING ENVIRONMENT.
EIRICH RV19 INTENSIVE MIXER: INCLINED PAN CREATES STRONG VERTICAL MIXING ACTION AGITATOR BLADES BREAK UP LUMPS AND DISTRIBUTE WATER WATER AND CEMENT IS DRAWN THROUGH THE MIX BY A VORTEX CREATED AT THE SHAFT COMBINED FLOOR AND WALL SCRAPER DIVERTS MATERIAL INTO THE PATH OF THE AGITATOR FLOOR SCRAPER ALSO ASSISTS WITH FAST DISCHARGE
H. Birkenmayer • Website: www.birkenmayer.co.za • Tel: +27 11 970 3880 • E-mail: email@example.com
(Above and left): Quality manufactured products are factory-made to exact specifications.
CMA PUNTS QUALITY CONCRETE TO AVOID FAILURES A sure way of ensuring the procurement
CMA membership should be a non-nego-
of quality precast concrete products is
tiable starting point for building profes-
by dealing with Concrete Manufacturers
sionals, as well as for end-users wanting
Association (CMA) member companies.
quality precast concrete products. End-
Frans Minnaar, outgoing executive
users, in particular, need to be aware of
director of the CMA, explains that the
the value of dealing with CMA members.
association is a non-profit company
“The CMA logo is used in various
with the well-being of end-users and
ways, either as an additional logo on
the industry at heart. It therefore only
stationery or as a sticker on a vehicle,
allows membership from producers of
or on social media, etc. The use of this
precast concrete products that comply
logo is limited to valid members of the
with strict standards set by the CMA
CMA, a list of whom is published on the
and the industry.
CMA website (www.cma.org.za) or in
As a result, member companies must
Precast magazine. Misuse of the logo is
have in place a quality management sys-
difficult to control, although the media
tem which has been entrenched in the
and stationery are regularly scanned and
manufacturing process of its products.
action is taken against those who falsely
Furthermore, where South African Na-
claim to be members.
tional Standard (SANS) specifications
“If a quality management system is
are required for the product manufac-
entrenched by a producer, the quality
tured, the applicant must also prove
of the product should always be under
that the product complies consistently
control. For a product to comply with the
with the requirements of the relevant
requirements of a specification naturally,
the quality of the concrete will play a
In these instances, the producer will either obtain the CMA Certification Services mark of approval or the SABS mark of approval, in which case the producer will be audited and its products tested for compliance on a regular basis by qualified auditors. Fighting for quality “In an otherwise unregulated industry,
PRECAST | ISSUE TWO | 2018
major role in success.
“Informal manufacturing of precast concrete products should not be encouraged.”
wire (if used at all), moulds or formers which
“This brings us to the question: what is
are of very poor quality or custom-made
good-quality concrete? With an imple-
out of scrap metal, mixing done by hand in
mented quality system, every aspect of
inconsistent ways, contaminated river or
the manufacturing of the concrete will
dam/pond water, uneven working surfaces,
be controlled, including procurement of
soil being mixed into concrete mixes, lack
raw materials from legitimate suppliers,
of control over compaction of the concrete,
confirmation of the quality of the raw
dimensions which are out of specification,
materials, the quality
and green product which
and calibration of equip-
is damaged during de-
ment with which the con-
moulding and handling,
crete is manufactured,
or which is placed on un-
the condition of plant
even surfaces for short
and forms (moulds), the
periods of drying out (no
assembly of moulds or
curing) before being sold
forms, the proper design
as final product.
of concrete mixes, the
There is no inspection
controlled application of
and testing done in most
raw materials to the mix,
ins t anc e s and ther e -
mixing times of mixes,
f or e also no c onsis t-
testing or inspection of
ency in the dimensions
and strengths of these
handling of freshly mixed
concrete, application to
are seldom paid minimum
the f orms or moulds,
wages and are usually not
compaction of the fresh concrete, strip-
trained thoroughly. No PPE is made available
ping of green product from mould or forms,
to employees and they do not have official
handling of green product, after-care and/
appointments. As a result, these informal
or curing of new products, handling of
producers cannot fulfil the necessary
products after curing, storage facilities
requirements and manufacture inferior-
and delivery to clients.
quality products which do not comply with
“Then there’s the quality control part of
any specification or standards.
the process: inspection of raw materials for compliance with required specifications,
checking of measuring and test equipment,
End-users of precast concrete products
inspection and testing of equipment and
should therefore be informed about the
plant before manufacturing, pre-deter-
detrimental ef fects of using inferior-
mined in-process inspections and testing,
quality precast products. The use of these
final product inspection and testing, keeping
products is the cause of many failures of
of evidence of compliance and release of
structures, the loss of huge amounts of
complying product to the client. All these
money and even the loss of lives. In ad-
processes must be controlled and managed
dition, it causes mistrust in the use of
to ensure the client always receives a good-
quality product,” says Minnaar.
“Government, local authorities, municipalities, developers and the general public
should be informed in every possible way
From the above, it is clear that informal
about the pitfalls of using the cheapest
manufacturing of precast concrete prod-
or inferior products. Reputable producers
ucts should not be encouraged. In order to
will be able to provide customers with the
manufacture good-quality concrete, manu-
necessary evidence of good quality and any
facturers require access to good-quality
customers using contractors should insist
raw material, which is not always readily
on seeing evidence of materials compliance
available to informal producers. As a result,
before accepting them for a project. It is
they use raw materials and practices which
easy to confirm whether a precast con-
are totally unsuitable for manufacturing of
crete product supplier is a member of the
precast concrete, such as inferior-quality
CMA or whether products bear the CMA
cement, stone and sand being replaced by
CS mark of approval,” says Minnaar.
soil or building rubble, proper reinforcing being replaced by pieces of scrap metal or
(Above): Frans Minnaar, outgoing executive director of the CMA.
PRECAST | ISSUE TWO | 2018
CEMENT PRODUCER SUPPORTS PRECAST INDUSTRY
innovations that add value to customers’ quality efforts, as well as their bottom lines. Having these local resources, plus an abundance of global knowledge and skills, is a major benefit for the entire precast concrete industry in SA. In order to ensure our customers can out-compete their opposition, our focus always remains on being customer-centric and providing sustainable solutions that are tailored to the needs of each customer.
The precast concrete manufacturing
our business. However, this segment is
What would you consider the biggest
industry is one of the largest single
the area with the most potential to offer
opportunity to increase market share
markets for cement producers in SA. In
additional value offerings and services.
this market the price of raw materials,
Our customer-centric approach is not
such as cement, has a large role to play
The precast industry is a major user
only our biggest thread, but our most
in the overall profitability of the precast
of your cement. How do you see your
important one. With that as the basis, the
involvement with this sector of the
entire process from start to finish cen-
industry, going forward?
tres on the customer’s desired outcomes.
and price-sensitive environment, but as
As the leader in construction materi-
Our golden thread is innovation and provid-
seasoned campaigners know, there is
als globally, Lafarge Industries SA re-
ing solutions that are sustainable
far more to buying cement than merely
mains committed to this market. Going
choosing the bag with the cheapest
forward, we’ll also remain innovative
What effect does imported cement have
through technology and solutions in an
on South African producers?
As a leading cement producer locally,
effort to provide for our customers’ re-
As a global-based company, we’ve in-
Lafarge Industries SA views the success
quirements. We believe that we’re best
vested in the country not only to grow
of the precast industry as a key ingredient
positioned to add value to the customers
its wealth, but also to create decent
in its own success. Commercial director
in this segment.
jobs in line with our National Development
This makes for a highly competitive
Alta Theron and country manager: com-
Plan. Imported cement is countering this
munications, Thami Nkadimeng, recently
How do you differentiate yourself and
very notion and putting pressure on the
opened the lid on the company’s plans for
your product from the other major
the industry in an exclusive question and
South African producers?
answer session with Precast magazine:
Lafarge SA prides itself on innovative
* Precast magazine approached all the
solutions, quality products, consistent
major producers in SA to comment on
How important is the precast market
performance and superior technical sup-
the importance of the precast concrete
sector to you as a cement producer?
port. We operate one of the largest civil
industry. Lafarge Industries SA was the
The precast market makes up a signifi-
engineering laboratories in the country,
only producer to respond.
cant portion of the volumes sold by any
with highly skilled personnel. These tech-
cement producer. Any market sector is
nical resources are designed to support
imperative, given the diverse nature of
our technical sales teams on a daily basis.
(Above): Lafarge bagged products for the precast concrete manufacturing industry. The company also supplies bulk cement sales, as required.
TRAINING ON JBCC BUILDING CONTRACTS The Joint Building Contracts Commit-
constituents’ regional offices and offers
• 15 August: Garden Court,
tee (JBCC) has announced the dates of
short, intensive training courses on the
its training workshops for the second
appropriate application of these agree-
• 16 August: The Beach Hotel,
half of 2018. The JBCC comprises nine
ments throughout the subcontinent.
East London. Marine Drive, Port Elizabeth.
constituents that represent the con-
Uwe Putlitz, CEO of the JBCC, per-
struction industry (owners and develop-
sonally conducts the one-day training
ers, contractors, subcontractors and
workshops from 8am-4.30pm, which – in
• 12 September: Sports Science
related professions) and whose members
all cases – earn delegates one Continuing
volunteer their services and knowledge
Professional Development credit.
• 3 October: Bytes Conference
• 5 September: The Country Club Johannesburg, Auckland Park. Institute of SA, Cape Town.
to draft building contracts containing
Training in the “Principal Building
an equitable distribution of contractual
Agreement and Nominated/Selected
risk. The JBCC supplies these agreement
Subcontract Agreement” for the second
• 14 November: 18 Burlington B&B
documents to all users through the
semester of 2018 will take place on:
PRECAST | ISSUE TWO | 2018
Together they’re able to come up with
Centre, Halfway Gardens, Midrand,
& Conference Venue, Durban.
INDUSTRY NEWS 10
HONORARY LIFE MEMBERSHIP FOR FLOORING DOYEN Neil Duncan, a respected leader in
Training Association (FITA) which regis-
the South African flooring and building
ters, accredits and provides training of
industry, has been awarded Honorary
flooring installers nationally, and serves
Life Membership by Master Builders
as one of FITA’s directors.
Association (MBA) North.
Apart from his involvement in the
D un c an, cur r en tl y dir e c t or an d
flooring industry, Duncan has also played
formerly chief financial officer of KBAC
voluntary and key roles in the building
Flooring, is among the pioneer s of
industry overall over the past 44 years.
training in the flooring sector, having
A qualified Chartered Accountant, he
successfully implemented an internal
has, for example, served as trustee
training programme at KBAC Flooring –
and principal of ficer of the Gauteng
an initiative which has already resulted
Building Industry Pension & Provident
in 30 KBAC flooring installers acquiring
Fund, honorary treasurer of MBA North,
executive committee member of MBA
He has also been instrumental in the
North and president of MBA North in
establishment of the Flooring Industry
2006 and 2007.
(Above): Neil Duncan (right), director of KBAC Flooring, receives the Honorary Life Membership bestowed on him by MBA North from the association’s president, Jason Wilmot.
ALL SYSTEMS GO FOR INDUSTRY’S TCC 2018 Afrisam has shown its commitment
He adds that the first day’s pro-
to the concrete industry associations
ceedings will culminate in a gala dinner
through its headline sponsorship for
where the SARMA ready-mix awards
The Concrete Conference 2018 (TCC).
will be presented, bolstered by top-rack
Other corporate companies that
entertainment and acts that include
have invested in the success of the
singer/drummer/comedian and the even-
conference are Chryso, PPC, Sephaku
ing’s MC, Gino Fabbri.
Cement and KonkreteGlobal with sponsorships of breakaway events such as
Highlights and speakers
the Concrete Quiz, which takes place
• Prof Henk Jonkers from the Delft Uni-
the night prior to the conference on
versity of Technology will be present-
31 July 2018 at High Flyers on the
ing a paper on technology behind self-
same premises, as well as sponsoring
refreshments, lunch and pre-dinner
• Max Moyo, world-renowned speaker,
will motivate and lead delegates into
Underlining the importance of this joint event is the strong support from
• L e o n v a n d e r We s t h u i z e n f r o m
some of the best-known names in the
industry who will be exhibiting at the
• Allesandro Bernacchia from Germany
event, including Afrisam, Mapei, Chryso,
and Andrea Bonomi from Italy will be
Sika, Nissan, Basilisk Self-Healing Con-
presenting case studies on extrusion
crete, Isuzu and Carmix.
kerbing and mobile batching respectively.
Johan van Wyk, organiser of TCC,
BrainRx will do some brain training.
• TCC will feature feedback on the
says: “Basilisk will be launching its self-
state of concrete standards, includ-
healing concrete at the conference.
ing concrete test methods, aggre-
Imagine that – concrete which heals
gate test methods, water-retaining
cracks! And KonkreteGlobal will show
structures and design codes.
the first robotic non-entry ready-mix
• There will also be a feedback and panel
truck cleaning system in SA. At the
discussion on the consolidation of the
same time, Isuzu Truck World will have
concrete industry associations.
a surprise for ready-mix concrete op-
• Other speakers will discuss energy-
erators and several other exhibitors will launch new ranges of equipment, concr e te addi ti v es, adhesi v es and much more.”
(Above, from top): TCC 2017 brought together the industry associations and all the role-players; Johan van Wyk is the chairman of the organising committee of The Concrete Conference.
ef ficient concrete roofs, cellular
concrete and case studies on the
Bosjes Chapel, Fourways Mall pre-
cast concrete and Zeitz MOCAA.
PRECAST | ISSUE TWO | 2018
EXECUTIVE DIRECTOR RETIRES
A strong foundation for infrastructure success
Af ter a productive and event-filled time as executive director of the CMA, Frans Minnaar has decided to step down from his busy role to enjoy the finer things in life and spend quality time with his family. Under Frans’s tenure at the CMA, the association has achieved much recognition for its role in promoting and representing the views of the precast concrete manufacturing industry in SA. Chief among these is undoubtedly the successful launch and implementation of the Concrete Manufacturers Association Certification Service (CMACS) as an alternative to the SABS system. Frans had responded to calls from members who had waited in vain for months or years for the old certification service to test their products by the SABS. This led to the rapid deployment of the association’s own CMACS service, which will also serve as a model to partially fund the association in future. He was also responsible for a host of other innovations which were introduced to assist members and streamline the operation of the business. Unfortunately, during the same period, the country’s economy had stagnated and funding of the association was becoming increasingly challenging. The withdrawal of a major long-term sponsorship plunged the CMA into further financial difficulties, which Frans had to overcome in order to ensure the survival of the association. However, with frugal spending and careful manoeuvering, he ably steered the CMA to relative safety and has decided to use the current peaceful period to announce his retirement. “I plan to join my wife in Cape Town and travel with her wherever her contracts take her. I’ll also pursue a quieter work life with some consulting, less pressure and more time to myself.” In addition, he will focus on recuperating to full fitness, having spent several months recovering from a major back operation at the beginning of this year. The association will be placed in the capable hands of the current marketing manager, Henry Cockcroft, who will be promoted to the position of general manager. He will be assisted by Charlotte Swanepoel as financial manager. They will report to the board of directors on a monthly basis during the monthly meetings normally held in the CMA boardroom. The board of directors has requested that a notice be served to all members that there is a need for at least one extra nonexecutive director to serve on the board. In the best interests of the CMA, it is important to have a diverse
ROCLA is South Africa’s leading manufacturer of pre-cast concrete products. Surpassing 100 years of product excellence, including pipes, culverts, manholes, poles, retaining walls, roadside furniture, sanitation and other related products within infrastructure development and related industries.
board of directors to represent all the different pillars of the association. Members will receive nomination forms before the AGM. Thank you, Frans, and good luck with your future endeavours!
PRECAST | ISSUE TWO | 2018
Visit us on www.rocla.co.za for our nationwide branches
INDUSTRY NEWS 12
REGIONAL MEETING WILL HELP DETERMINE CMA PATH The Gauteng regional meeting held in Ger-
Either way, obtaining sufficient funds
Other topics of discussion included
miston recently marked a watershed for
to keep the association running ef-
the urgent need to address skills short-
the Concrete Manufacturers Association
fectively remains a moot point and one
ages in the industry, training, policing
(CMA) and its members as the floor was
that was put to the floor for discussion.
of false claims of membership and main-
opened for discussions on several path-
Members also heard how the current
taining high standards within the indus-
changing decisions that lie ahead for the
tough economic climate has eaten into
try. Findings based on input from the
association in the near future.
the association’s reserves and requires
nationwide round of regional meetings
future funding models to be cognisant of
will be further collated and discussed,
whereafter findings and suggestions will
Firstly, outgoing executive director Frans Minnaar updated delegates on the status of talks to consolidate the
Simultaneously, members heard that
various concrete-related bodies into a
the CMA Certification Services is find-
single representative body. While tra-
ing traction and is increasingly being
ditional funding from the country’s six
recognised as the de facto concrete
major cement producers will potentially
product certification of discerning engi-
be withdrawn from separate entities
neers. In fact, so high is the demand for
(including the CMA, the Southern Africa
certifications that the company and its
Readymix Association, The Concrete
team are being thoroughly stretched to
Institute and the Concrete Society of
ensure fast and efficient turnaround. It
Southern Africa) unless the consolidation
was also noted that CMA CS is already
takes place, CMA members also voiced
nearing break-even point in terms of
their concerns that a single umbrella
profitability and will soon be in a position
body may not adequately represent the
to begin repaying the CMA’s initial and
association in future.
be tabled to all members in the weeks that follow.
(Above): CMA members attended the recent Gauteng leg of the 2018 round of regional meetings.
The CMA hosted a members’ feedback
Cockcroft’s presentation covered the
had been the best competition to date.
meeting in Cape Town on 22 May 2018.
past year’s achievements, the member-
This year’s panel of independent judges
Presented by CMA outgoing executive
ship drive, the CMA CS and its website,
were drawn from the Universities of the
director Frans Minnaar and marketing
Precast magazine, the 2018 Awards for
Witwatersrand and Pretoria, the Master
manager Henry Cockcroft, the event
Excellence Competition, conferences,
Builders’ Association, ILASA and SAIA.
was held to apprise members of what
expos and technical workshops.
Cockcroft said that the structure of the
the association had achieved during the
He said a roof tile workshop which
competition had been reconfigured on a
previous 12 months and its plans for the
was jointly sponsored by Aveng Infraset,
product category basis, which meant
Monier Coverland and Marley had been
that more companies stood a chance of
The association’s financial position
a great success. It was presented by
winning an award. There were 100 en-
was first on the agenda. While there were
Danie Hattingh of Monier Coverland and
tries, 18 of which garnered awards and
some notable fundraising successes,
attended by close on 80 delegates, mainly
four of which received overall trophies.
such as various workshops and the CMA
He noted that this had already seen
Awards function, Minnaar said that if
Cockcroft also mentioned that the
the CMA active in several concrete
current conditions prevailed, the CMA
CMA CS had revolutionised precast
promotional events: The Concrete Con-
would post a net loss for the current
unit quality standard assessment and
ference which was held in August 2017,
financial year. This was mainly due to a
certification and was attracting the at-
jointly organised by the CMA, TCI, SARMA
lack of major sponsorships. In addition,
tention of some of the major players in
and the CSSA . T he CM A member s
several action plans are being investi-
the concrete industry. Moreover it was
presented several case studies at the
gated to improve the financial position
anticipated that by the end of the year,
conference. The CMA also participated in
of the association.
60 permits would have been issued by
the KZN Construction Expo in February
the CMA CS.
2018, in another joint initiative with TCI,
On a more positive note, Minnaar mentioned that the CMA’s Certification
Several technical manuals and publica-
SARMA and the CSSA and in two other
& Mark of Approval (CMA CS) arm, which
tions have been proposed for the current
joint events this year, BAUMA in April
specialises in the auditing of precast
year. They include a wet cast specifica-
and Totally Concrete in May.
concrete production, was financially
tion which has been submitted to the
In the immediate wake of Bauma, the
self-sufficient and in a position to begin
SABS Standards Committee, a cost
CMA was a joint organiser and host, to-
paying back a CMA loan.
comparison survey on roof tiles versus
gether with Pan Mixers SA, of a seminar
The CMA is not alone in feeling the
other coverings, cement bricks versus
on pigmentation and advanced colour
impact of a spluttering economy and is
clay bricks, a concrete versus plastic
metering systems. It was presented by
one of five associations which the cement
pipes manual and a new segmented paving
two global experts on pigment dosing and
producers are no longer willing to support
dispensing: Hans J de Witte, a world-
as independent entities. In light of this,
Cockcroft added that the main focus
leading specialist in inorganic pigments
Minnaar mentioned that discussions are
of the membership drive was on reviving
and Michael Finke, managing director
underway with local cement producers
membership in KwaZulu-Natal and the
of Finke Dosiertechnik GmbH, Germany.
to consolidate the country’s cement and
Western Cape. The CMA is also seeking
The meeting was concluded when
concrete organisations into one body.
to rekindle relationships with resigned
delegates were given two questions to
ponder on during the coming months: “Of
The consolidation initiative is being driven by a working group (CWG) to
T he 2018 Awards for E xcellence
what value is CMA membership to you?”
formulate proposals for presentation
competition was a resounding triumph,
and “How can the CMA improve its of-
to the cement industry. Other associa-
with many of the participants saying it
fering to members?”
tions being considered for inclusion are the Concrete Institute, the SA Readymix Association (SARMA) and the Association of Cementitious Material Producers (ACMP). Minnaar said that the CMA’s board of directors had expressed reservations about the consolidation, especially as CMA CS was now financially viable. Likewise, the ACMP felt that its association would not fit into the new structure. While preliminary discussions are underway, the CMA board has agreed that Minnaar should represent the association on the CWG.
PRECAST | ISSUE TWO | 2018
YEAR AT A GLANCE AT WC REGIONALS
MANUFACTURER SUPPORTS EDUCATION The IS Group has provided funding in the form of a donation in cash and kind to the value of R743 000 to assist in the construction of 10 new classrooms for
the Lompec Education Centre in Mamelodi East. The centre is providing much-needed educational facilities to the local community and growing demand recently made it necessary to expand the centre and separate the junior school from the high school. The IS Group of companies came on board to assist in the expansion of the centre by donating materials and funding. T h e d o n a ti o n w a s us e d f o r th e manufacture and delivery of 1 635m2 of Technicrete Bond Brick pavers, 77m
(Above): A classroom at the Lompec Education Centre nears completion.
of Figure 7 1 000mm kerbs, 2 200
much-needed expansion programme. In
“Access to education is crucial for
Technicrete Earthform grey retaining wall
addition to the bricks and kerbs, we were
the upliftment and skills development of
blocks and 87 000 Ocon Brick clay stock
able to complete two sections of the
previously disadvantaged communities.
bricks. A cash portion of R456 590 was
school with ready-mix concrete, which
Without education, there’s no future.
also donated to Lompec and used to fund
was cast on the first floor. Reinforcement
When we heard about the need for extra
the new classrooms, as well as a library
steel was purchased and, along with the
classrooms and learning facilities at
and a computer facility.
donated bricks, enabled us to complete
Lompec Education Centre, we offered
two wings,” says Barnard Mashiane, Emis
to donate, through the manufacture and
officer: Lompec Education Centre.
transportation of materials required,
“We were delighted when the IS Group informed us it would be assisting in the
and assist in the centre’s expansion,” Education for the future The Lompec Education Centre offers conventional education from pre-grade
says Malebusa Sebatane, group marketing and communications manager for the IS Group.
R up to Grade 12, delivering good results. In 2017, the centre was staffed by
“The financial donation by the IS Group
41 educators overseeing 924 pupils. Lompec engages in skills development
will enable us to buy paint and floor tiles,
by partnering with local universities in teacher training and during 2017,
as well as complete the stormwater erec-
it monitored four Unisa students and one University of Pretoria student.
tion, paving installation, electrification
Additionally, it awarded bursaries to five pupils.
elements and finishing touches to Section C of the school,” says Mashiane.
ATTRACTIVE, FUNCTIONAL AND DURABLE PAVING Appearance is a key selling point for
autumn, terracotta, plum, grey, slate
residential and commercial properties,
as it is for attracting customers to
It is a very functional and durable paver,
petrol stations and parking facilities, so
which enhances the final appearance of
the choice of paving plays an important
any petrol station forecourt, municipal
role in the final design of developments.
parking area, pathway, commercial or
It is therefore not surprising that
residential development, factory road
Technicrete’s Conleaf smart and durable
or suburban street.
pavers are often specified by architects
T he C onle a f is manu f ac tur e d in
and developers in order to obtain the
a 55mm or 60mm thickness, with a
desired attractive finish to a project.
200 x 200mm length/width. A larger
T he C onlea f p a v ing block o f f er s
80mm paver is available upon request.
attractive patterns and lines through
Te c h n i c r e t e I S G i s p a r t o f t h e
its unique, sof t, curved appearance
Infrastructure Specialist Group, which
and a choice of colours that includes
also comprises Rocla and Ocon Brick.
PRECAST | ISSUE TWO | 2018
PRODUCTS TO OBTAIN A LIST OF CERTIFIED SUPPLIERS, CONTACT CMA CERTIFICATION SERVICES OR VISIT WWW.CMA.ORG.ZA. Address: Office 0400, Standard Plaza Building, 440 Hilda Street, Hatfield, Pretoria, 0083 Tel: (011) 805 6742 â€¢ Email: firstname.lastname@example.org
YOUR MARK OF QUALITY IN PRECAST CONCRETE
COMPANY NEWS 16
PRECAST MANUFACTURER CONDUCTS SUITABILITY STUDIES FOR PROJECTS Precast concrete manufacturer Elematic
a precast concrete solution, namely
required for adapting precast construc-
is offering a service to developers and
choosing the most suitable concept de-
tion, such as basis of structural analysis
contractors to determine the benefits
sign office, preparing for concept design
and design, outline structural framing
of moving from traditional construction
project and concept design.
and precast arrangement.
methods to construction of precast concrete structures.
When considering a new construction
In addition, typical connection details
method, it is important to have a profes-
of various precast elements, sizing, geo-
While precast structures offer many
sional partner to work with in order to
metrical details and number of precast
cost- and time-savings for construction
achieve the best possible outcome. It is
product types, including reinforcement,
projects, evaluation of these benefits
also important to consider whether en-
pre-stressing and concrete strengths,
in terms of clear cost calculations and
gineers on the project have sound knowl-
are required. The final report should
precast product selection is essential.
edge of precast industry developments,
also consider suggested changes to
For this reason, the company is offering
practical knowledge and geographically
architectural design for efficient building
a concept design service to those wishing
and details of production set-up/precast
to make the switch.
The engineers should also have a good
machinery and equipment requirements.
“The service is available globally and
knowledge of precast production, plant
assists our customers in understanding
operations and efficient working meth-
the feasibility of adopting this technology,
ods, as well as structural connections
Elematic technology and assistance are
as it includes an evaluation of how their
and solid experience.
already being successfully utilised in
current and future projects could be
Gauteng and the Western Cape in SA for
structured using precast and whether to
Scope of projects
affordable housing developments by local
use complete or composite structures.
The starting point in evaluating the
municipalities, as well as private property
The performance of the precast building
suitability of precast for a project is
in local gr ound conditions and the
understanding the project in totality.
“Besides the feasibility studies, we
required precast product types are also
Architectural drawings – including lay-
assist in the finalising of building details
evaluated,” says Prakash Shah, head
outs, elevations, sections and special
and the setting up of a precast plant. Our
technical support of Elematic India.
features – are required, as well as de-
commitment is to our customer base and
tails of building utility service arrange-
we promise a lifetime commitment from
ments, local seismic details and costs
design to the complete life-cycle of the
With its global experience in precast
of structural materials.
factory” says Shah.
production and application, Elematic can
The end result of a concept design
provide assistance throughout the pro-
project is the final reporting, which
cess required to successfully implement
includes all the information that will be
(Above): A typical precast structure using Elematic units.
PRECAST | ISSUE TWO | 2018
POTENTIAL FOR PRECAST ECA manufacturers claim the material is up to four to five times lighter than traditional aggregates, with a host of benefits that can be harnessed to produce special concretes ranging from
Worldwide, the use of expanded clay aggregates (ECA) is finding favour among concrete manufacturers for the production of lightweight, yet strong blocks and slabs for use in the construction of thermally efficient buildings and other specialised applications.
chemical-resistant, sound-dampening and thermally efficient varieties to fire-
market, including for the manufacture
results for use on non-load-bearing
resistant and lightweight concretes.
of blocks, thermal panels, landscaping
walls and would surely find applications
products, fire, acoustic and other con-
in southern Africa. Different mixes and
aggregates sizes may produce even
The properties of the material are made possible through careful control
better results for external walls, slabs,
of different types and sizes of expanded
ECA is usually produced in different
clay products as they are processed.
sizes and densities from 0-30mm, com-
During the cycle, the clay pellets are
monly 0-1mm, 0-2mm, 2-8mm, 2-8mm
However, looking at the specifications
heated and cooled to temperatures
Crushed, 8-15mm and 15-30mm and
of the company’s commonly manufac-
exceeding 1 200˚C in a rotary kiln. This
densities from 260-700kg/m3.
tured blocks, it produces good properties
roof tiles, etc.
provides the desired effect of expand-
This provides characteristics such
in post-curing, with good overall finish
ing the clay particles and gives them a
as lightness, thermal insulation by low
and thermal insulation properties. These
honeycombed void structure.
conductivity co-ef ficient (as low as
are typical technical specifications:
0,097W/mK ), soundproofing by high
• Dry density: 600-750kg/m3
acoustic resistance, moisture imperme-
Overseas, it seems that a large part of
ability, incompressibility under perma-
• Drying shrinkage: 0,005%
the appeal of the material is its predict-
nent pressure and gravity loads, non-
• Compressive strength:
able density, geometry and shape, which
decomposition against severe condition,
can be harnessed to give accurate cal-
fire-resistance, ease of transport and
• Flexural strength: 1,05N/mm2
culations of performance and strength
a reduction of construction dead load.
• Thermal conductivity: 0,14-0,18W/mk
(average value = 700kg/m3)
• Sound insulation index: Up to 46dB
for use in speciality mixes. Moreover, its spherical surface is rough with a
for 100mm-thick walls and up to 52dB
semi-porous finish which provides good
Examples of blocks manufactured using
for 2 30mm-thick walls.
adhesion for concrete crystallisation.
ECA, fly ash and cement produce good
All these properties previously popularised the aggregate in the horticultural industry, where it has been extensively used for drainage and moisture retention purposes and for the growing of seeds. Other large-scale applications in geotechnical and earth stabilisation applications have led to the material being made more widely available and contributed to its cost-effectiveness for use in specialised concrete mixes. A quick search also reveals that at least one locally manufactured product
“At least one locally manufactured product is available, with several overseas suppliers also seeking to establish themselves in the market.”
Potential benefits The blocks are also marketed to have a number of benefits that are potentially useful in certain applications, including the lightweight ability to reduce structural loads by 40-50%, excellent thermal performance, sound insulation abilities and high compressive strength, as well as resistance to fire, chemicals, water absorption, termites and pests. Concrete manufactured using ECA can be drilled, carved, nailed and shaped and is easily plastered or coated.
is available, with several overseas suppli-
With competition mounting in the
ers also seeking to establish themselves
precast concrete industry, the introduc-
in the market. One such company is
tion of new technologies may carve new
Rivashaa Eco Design Solutions from
niches for manufacturers who are willing
India, which has been actively marketing its services and products in SA.
to take a chance and explore new opportunities. Whether ECA or other newer technologies will find favour
among our concrete manufactur-
Accor ding to the company’s
ers and lead to the proliferation
literature, there are a number
of exciting new products remains
of products suited to the local
to be seen.
PRECAST | ISSUE TWO | 2018
NEW AGGREGATE HAS EXCITING
AROUND & ABOUT 18
EXCELLENCE ON DISPLAY The CMA Awards for Excellence 2018 held recently at The Venue in Melrose Arch, Johannesburg, provided all the glitz and glamour expected from one of the construction industry’s premier events. It also allowed the CMA’s members to show what the industry is capable of, while simultaneously offering a muchneeded opportunity to network among peers. Above all, the event provided a chance for everyone to let their hair down and celebrate the industry’s success. The pictures say 1 000 words….
PRECAST | ISSUE TWO | 2018
PRECAST | ISSUE TWO | 2018
TOP ARCHITECTURE STUDENT AWARDED FOR NEW DISTRICT SIX VISION An architectural student with a modern
Swett Arquitectos and is a respected
vision for District Six has walked away
writer and designer;
with top honours at this year’s PPC
• Maria Fernanda Derntl, author and
Imaginarium Awards for Architecture
held in Pretoria recently.
• Award-winning architect Nadia Tromp
R o a r k R o b i n s o n, a 2 2 - y e a r - o l d
professor at the University of Brasilia; of Ntsika Architecture; and
student from the University of Cape
• Award-winning studioMAS architect
Town, received the award including a cash
Heidi Boulanger (Van Eeden).
prize of R50 000 for his outstanding
The judges chose Robinson’s proposed
design project which envisages a “public,
Artisan Centre for District Six in Cape
connective architecture” for a District
Town as the overall winner. According to
Six of the future.
this budding young architect: “District
Architecture schools across south-
Six stands vacant and scarred as one of
ern Africa were invited to submit works
the greatest exhibitions of apartheid-era
by final-year students for consideration.
planning reinforcement. As one of the
All 21 finalists’ projects were on exhibi-
pioneering redevelopments of the area,
tion at the 012 Central Gallery as part
the building aims to set a precedent for
of the Architecture ZA (AZA) Confer-
future developments, encouraging acts
ence programme. In keeping with the
of public, connective architecture and
AZA’s theme of resilience and memory,
creating the first framed public space
entrants were asked to locate a “hole”
in the area.”
in urban infrastructure caused by rapid
Fellow UCT students Anna Stelzner
growth and change, and to contribute
and Ilaena Napier were declared the
to spatial transformation by addressing
runners-up and received a cash prize of
connections between the community’s
R20 000 each. Two additional commen-
memory and resilience.
dations were bestowed on the entries
The entries were judged at the AZA
of Nelson Mandela University students
by an international panel of architects,
Robert Duvenage and GP Greyvenstein.
some of whom formed part of the AZA
Robinson’s winning project will join the
speaker line-up. The judges included:
national travelling exhibition of the PPC
• Hermann Kamte, Cameroonian archi-
Imaginarium Awards, which includes all
tect and founder of the award-winning
category winners across fashion, sculp-
firm HKA | Herman Kamte & Associates;
ture, jewellery, film and industrial design.
• Prolific Chilean architect Enrique
The PPC Imaginarium Awards travelling
exhibition will be at the Turbine Art Fair
Browne, who co-founded Browne &
(12-15 July 2018) and 100% Design South Africa (8-13 August 2018). T he PP C Imaginar ium Awar ds is SA’s most supportive arts and design competition for emerging creatives. The BASA award-winning initiative encourages up-and-coming creatives to produce innovative designs from concrete. The 2018 round of the competition witnessed a record number of finalists chosen from the six entry categories, namely film, fashion, sculpture, jewellery, industrial design and ar chi t e c tur e. T he PP C Imaginarium Awards has now extended its reach from SA to Zimbabwe and is (Above): Roark Robinson won the 2018 PPC Imaginarium Award for Architecture.
running its first PPC Imaginarium Awards in Zimbabwe in 2018.
PRECAST | ISSUE TWO | 2018
(Above): Silvio Schade (left) seen here with Revelstone managing director, Andrew Cyprianos.
BFT INTERNATIONAL EDITOR VISITS CAPE CAST STONE MANUFACTURER Among the many visitors to this year’s Bauma Conexpo Africa was BFT International editor Silvio Schade, who stopped over in Cape Town en route to the exhibition in Johannesburg. BFT International is a widely respected publication which covers all aspects of precast concrete. Published in Germany in several languages, its readership extends to Europe and Russia, the USA, China, the Middle East, South East Asia, Australia, Africa and South America. Schade’s work has taken him to close on 30 countries and while in Cape Town, he took the opportunity to visit CMA producer member, Revelstone, one of the country’s most innovative producers of paving blocks and wall cladding. “We’re interested in monitoring developments in the precast concrete industry all over the world and at Revelstone, I was astonished to find something I hadn’t seen before, namely rubber moulds,” says Schade. “Besides being recyclable and eco-friendly, they enable Revelstone to produce a vast range of pavers to order, giving architects and landscape professionals huge scope for bespoke design options.” BFT International is in it’s 84th year and is issued by Bauverlag BV GmBH, the German construction industry publishing house, which publishes 17 other construction-related magazines covering architecture, the cement industry, masonry production, building trade and contractors, among others. The journal offers a mix of research material sourced from German universities, as well as project-and product-orientated material. “German academia has an excellent relationship with the construction industry and nine of our leading universities conduct ongoing research into the precast industry on an ongoing basis. Both sides benefit from the relationship; industry is fed a continuous stream of technological developments and the universities benefit from the financial backing of industry,” says Schade. He adds that precast concrete is the dominant material in multi-storey construction in Europe. “Masonry still plays a significant role in domestic construction, although wooden houses predominate in southern Germany. Some of the masonry units used in Germany are: autoclaved aerated concrete (AAC), clay white silicate stone, lightweight concrete blocks, and cement blocks which are mainly used in the construction of outbuildings,” says Schade.
PRECAST | ISSUE TWO | 2018
AVOIDING FAILURES IN THE INSTALLATION OF CONCRETE BLOCK PAVING ON CONCRETE ROOF DECKS Concrete block paving (CBP) is a very functional and attractive method of surfacing concrete roof decks and is SAâ€™s most widely used roof deck covering. Nevertheless, failures are all too common because crucial design elements are often side-stepped. Poor drainage is the major culprit, for several reasons: inadequate falls in the concrete slab; insufficient provision for surface run-off and, at times, a complete lack of drainage for subsurface water in the bedding sand. These and other issues are addressed in
its relevance. Cairns highlights the ele-
this article which has been culled from a
ments which must be taken into account
paper presented to an international pav-
under South African conditions for the
ing conference in 2000 by independent
design and installation of CBP on concrete
paving consultant, John Cairns. Given
slabs, particularly on outdoor roof decks.
the incidence of recurring roof deck pav-
Various types of drainage are examined in
ing failures, this topic has lost none of
detail and he makes recommendations,
(Left, from top): Expansion joints in the concrete slab must be continued through to the pavers to allow movement without opening or closing the gaps between pavers; An example of good drain detailing. Aesthetically pleasing and correctly sized, the drain has no unsightly in-situ concrete surround and it also captures the sub-surface water in the bedding sand (see Figure 2 detail).
illustrated with examples. A number of old asphalt roof decks (over 15 years) have been replaced with CBP due to deterioration in the asphalt and damage to the waterproofing membrane. However, even roof decks designed
PRECAST | ISSUE TWO | 2018
(Left): Different coloured pavers are used for the roadway and parking bays. Besides being aesthetically pleasing, they eliminate the need for painted bay lines.
able, but they must be designed to catch
(Above): Expansion joints in concrete slab must be continued through to the pavers to allow movement without opening or closing the gaps between pavers.
typical drain detail.
the sub-surface water from the bedding sand or deck drain. Figure 2 shows a It is also essential that the paving blocks are laid approximately 5mm above the level of the drain to ensure that the
Paving blocks do not require special consideration because they are only a
water flows into the drain and does not pond around it.
wearing surface. Pavers 50mm thick for pedestrian traffic or 60mm for vehicle
traffic are more than adequate. Perme-
Roof decks are of ten designed and
able pavers can also be considered for ap-
constructed without considering rain-
plications in which rainwater is required
fall drainage and concrete decks are
to pass through the CBP surface into a
frequently cast without falls. Falls can
drainage system below.
be created with screeds, but due to several constraints â€“ such as fixed levels
at entrances and exits, as well as weight
An adequate number of correctly sized
restrictions which limit screed thick-
drainage outlets must be strategically
ness â€“ decks often do not cater for drain-
positioned at the low points of the slab
to ensure ef fective drainage. Of ten
It is essential that decks are con-
with CBP from the outset can present
100mm diameter full-bore outlets are
structed with minimum falls in compliance
problems, either because certain critical
used and these are too small to cope
with SABS 1200 MJ, which are 1% in
aspects have not been included in the
with the large volumes of water during
the longitudinal direction and 2% in the
design, or the laying process has not been
severe downpours. In addition, during
transverse direction. This will prevent
properly executed. Besides slab move-
the dry season these outlets become
ponding, which is inconvenient to pedes-
ment, caused by temperature variations,
blocked with extraneous materials such
trians and causes excessive amounts of
drainage, vibration and edge restraints
as cigarette butts, plastic paper and
water to penetrate through the CBP. It
are all critical design considerations.
will also ensure that surface water and
A typical section through a roof deck is shown in Figure 1.
PRECAST | ISSUE TWO | 2018
Large rectangular drains (minimum 500mm x 500mm) are far more prefer-
any water that penetrates the paving flows into the drains.
SUB-SURFACE WATER In a study by the late Prof ShackelÂ˛, it was shown that approximately 25% of stormwater can penetrate the joints in newly-laid and unsealed CBP and even with sealing, some penetration still occurs. Therefore provision must be made to drain
any water which penetrates the paving. Water which does penetrate the paved surface should be kept to a minimum and to this end, proprietary water-activated jointing sand and/or liquid sealants should be applied to the joints. In both cases, it is essential that the joints are completely filled and regular sampling should be carried out by lifting the pavers for verification purposes. The loss of jointing sand due to trafficking is one of the
(Above): Good examples of aesthetically pleasing concrete block paved surfaces.
major causes of paving block movement, leading to saturation of the bedding sand
drains and this can cause differential
between adjacent paving blocks to open
and pumping and, ultimately, the failure of
settlement of the CBP.
up, resulting in a loss of jointing sand,
The preferred system is a continuous
excessive water ingress, CBP movement
Provided the falls are adequate and the
deck drainage layer beneath the bedding
and, eventually, the failure of the paving.
right quality of bedding sand is used, any
sand. This can be an open-graded granu-
It is therefore essential that control
water which penetrates the paving will
lar base or, alternatively, one of several
joints, complete with edge restraints on
flow to the drains. However, it is essential
proprietary membranes can be used.
either side, extend into the CBP. This can
that the grading of the bedding sand con-
The most common and suitable is a geo-
be simply achieved by casting an in-situ
forms to SABS 1200 MJ and it is prefer-
composite drain consisting of a studded
concrete upstand on either side of the
able that fine material (ie <0,075mm) is
polystyrene core covered with a strong
joint (see Figure 3) or bolting a steel angle
woven polypropylene filter fabric. This
onto the slab on either side of the joint
For non-trafficked roof decks, single-
woven fabric filter allows water to pass
(see Figure 4). The gap must naturally be
size pea gravel can be used as the bedding
into the drain core, while restricting any
suitably sealed to prevent water ingress.
layer and the joint can be left open for
dispersion of the bedding sand. Various
Alternatively, a proprietary expansion
rapid drainage. If the falls are inadequate
cores are available to suit the predicted
joint assembly as used on bridge decks
for suitable drainage of the bedding sand
volume of water and traffic loading.
can be attached to the concrete slab.
sand may become saturated, then a drain-
Movement of the concrete deck
coincide with the highpoints of the slab
age system must be installed beneath the
Concrete slabs are subject to substan-
to reduce the volume of water flowing
tial movement, mainly due to tempera-
across the joint.
the paved surface.
It is preferable for the control joint to
or if there is a concern that the bedding
One system which has been used is
ture variations, especially in instances
There will also be a certain amount of
a herringbone drainage pattern using
where there is no insulation layer above
deflection and vibration of the roof deck,
geotextile wick drains as the drainage
the slab. This movement is handled by
depending on spans, traffic intensity and
material. However, these drains tend to
installing control joints in the concrete
method of construction. If the deck is
become blocked and local pumping of the
slab at regular intervals and these must
post-tensioned, the vibrations may be sig-
bedding sand can occur as described in
extend through the CBP layer. There have
nificant and cause the dispersion of joint-
a paper by KnoesenÂł. It also results in
been many cases in which this provision
ing sand. In such cases, it is necessary to
the dispersion of bedding sand around
was ignored. This causes the joints
inspect the paved surface regularly and refill the joints until lock-up occurs. Edge restraints Typical edge restraints for roof deck CBP include buildings, protrusions and perimeter parapet walls. If there are segregated vehicle traffic lanes and pedestrian walkways, these can be normally demarcated with precast concrete kerbs in the standard manner.
If a masonry parapet wall is used as the edge restraint, it must be designed
PRECAST | ISSUE TWO | 2018
The normal precautions which are
ated by concrete slab movement. There
taken when laying CBP on steep slopes
are many cases of masonry walls crack-
should be used for access ramps, es-
ing due to these forces and in extreme
pecially the drainage aspects. If in-situ
cases, parapet walls have been pushed
concrete beams are used as anchor
off the edge of the slab.
blocks, they must include weep holes to
to withstand the horizontal forces cre-
It is recommended that an expansive
allow the free passage of water. And if
material be placed between the wall and
an insulation layer is placed above, rather
CBP and it is essential that the CBP slopes
than beneath a slab, it must be able to
away from the wall to prevent water pond-
withstand the static and dynamic loads
• All edge restraints must be capable of
ing. The joint between the wall and the CBP
of the traffic.
withstanding the loadings, both verti-
cal and horizontal.
should be sealed to prevent high volumes of water from entering the bedding sand. (See
typical details in Figures 5 and 6.)
• The drainage systems for both sur-
Two other aspects which are not only
face and sub-surface water are of
Roof deck CBP must be properly de-
related to roof decks, but need care-
paramount importance for roof deck
signed, detailed and constructed if it is
ful consideration are speed bumps and
CBP to perform adequately.
to perform without mishap.
access ramps, which tend to be fairly
• The volume of water penetrating
steep. Speed bumps must be designed
the CBP should be minimised by using
inspections – especially during their
to prevent high-impact forces causing
proprietary jointing sands and surface
early life – will highlight any minor faults,
movement of the CBP and it is strongly
which can generally be addressed at
recommended that they do not coincide
• The movement of the concrete deck
relatively small cost before they develop
with control joints.
into major problems.
must be catered for in the paved surface.
As with all CBP installations, regular
REFERENCES 1. SA Bureau of Standards standardised
specification for civil engineering
construction, 1200 MJ: Segmented
Paving, 1984. 2. Shackel, B (1988). An Experimental
Study of Methods for Sealing Concrete
Block Pavements. Proceedings of the
Third International Workshop on Con-
crete Block Paving, pp38-1 to 39-11.
3. Knoesen, L (2000). Rehabilitation of
Damaged Asphalt Paving Using
Concrete Block Paving on a National
Road in South Africa. Proceedings of
the Sixth International Conference
on Concrete Block Paving.
Figure 5 These images of a well-executed CBP installation on a concrete roof deck were taken in April 2018 at the Canal Walk Shopping Centre in Cape Town, 18 years after the pavers were laid.
Article courtesy John Cairns, JC Paving Consulting 079 884 7986 • email@example.com. • Day courses on all aspects of concrete block paving. • Advice on design and detailing of concrete block paving for residential, commercial and industrial applications. • Providing an expert opinion
PRECAST | ISSUE TWO | 2018
on failed paving or disputes.
caused by wheeled traffic on floors and pavements, as well as abrasive material, as in ore passes and silos, wearing down the surface of the concrete. Strong concrete with little surface laitance, well cured and finished off along with abrasive-resistant large aggregate, will slow down the rate at which the concrete
sur f ace we ar s. Specialist sur f ace hardeners will also help reduce wear. Cavitation: The collapse of very highpressure vapour bubbles, created by fluid jumping off the surface of the concrete due to sudden changes in direction of that fluid, can cause massive damage to the concrete within a short period. Aerating the fluid – as is often done on dam spillways – to prevent pressure build-up is an effective way of preventing cavitation. Salt crystallisation: This is often called “salt jacking” and tends to occur along the coast, where the concrete is subject to high concentrations of salt.
SOUND PRACTICE CAN EXTEND
Although concrete is an extremely robust and forgiving construction material, with almost all concrete placed outlasting its designed service life, some durability issues do crop up and can be overlooked.
Salt in solution is transported into the concrete and, when the concrete dries out, it recrystallises, with the resulting expanding salt crystal exfoliating the surface of the concrete. Freeze-thaw: Ingress of water into the concrete that subsequently freezes can cause the formation of cracks, due to the expansion of the ice. Air entrainment can effectively prevent this. The size and – more importantly – the spacing of the air bubbles are key factors in how effective the air entrainment will be. Chemical deterioration mechanism
Dissolution of hydration products: Acid attack: The calcium in the concrete hydrates has a high solubility in acids. Often a sacrificial calcareous aggregate
John Roxburgh, lecturer at The Concrete
known mechanisms that could lead to
is used to get an even wear and slower
Institute’s School of Concrete Technol-
deterioration of concrete. Durability
disintegration of the concrete surface.
ogy, outlines some of the less common
issues can generally be categorised
With strong acids, a sacrificial layer or an
durability issues that may be encoun-
under two main headings: mechanical
acid-resistant coating is more effective
tered in concrete practice. The corrosion
(and physical) deterioration, and chemical
in protecting the concrete.
of steel within the concrete is the most
deterioration. Chemical deterioration,
Soft or pure water attack: Waters
prevalent durability problem associated
furthermore, can be subdivided into the
with very low ion contents will cause
with concrete. For this reason, great
chemical dissolution of the hydration
the dissolution of the hydrates within
care is usually taken to ensure that the
products and the chemical conversion of
concrete. Soft or pure waters are often
correct reinforcing steel is placed in the
the hydration products.
those which have not come into contact
correct position with enough concrete
with calcareous rock.
Chemical conver sion of hydration
cover to it. However, what is sometimes
Mechanical (and physical) deterioration
overlooked is the environment into which
the concrete is placed – a factor that
Erosion and abrasion: Erosion is caused
Alkali silica reaction (ASR): Silica
could negatively impact the planned du-
by fluids, most often water, containing
contained in the aggregate can react
abrasive particles wearing down the
with active alkalis within the concrete
surface of the concrete. Abrasion is
pore structure. This forms an expansive
Listed below are a few of the better-
PRECAST | ISSUE TWO | 2018
Interestingly, all of the above deterio-
by ensuring excellent compaction and
Avoiding aggregates containing reactive
ration mechanisms can be mitigated or
optimising curing. By doing this, the con-
silica, minimising the active alkalis within
even prevented by designing the concrete
crete will be less permeable, which is key
the concrete and preventing the ingress
mix with a lower water-to-cement ratio
to a more durable concrete.
of water into the concrete are effective
and implementing good site practice
measures in preventing ASR.
Although the mechanisms mentioned above are by no means exhaustive with
Sulphate attack: A combination
regard to concrete’s durability, they
of sulphates, calcium hydroxide and
serve to illustrate the wide spectrum
tricalcium aluminates in the concrete can
of environments to which concrete
lead to the formation of two expansive
may be subjected. There are many well-
compounds: gypsum and ettringite.
researched methods of ensuring that
This can cause the concrete to soften
concrete will perform for its service
and crack. Using sulphate-resisting
life within any specific environment.
cement or extending the cement with
However, it is important that engineers
fly ash or slag can help prevent sulphate
and concrete practitioners take heed of
attack on the concrete. In addition,
these environments to avoid potential
ensuring that the sulphate content in
the aggregate and mixing water is kept
(Left): Surface exfoliation of concrete pavers caused by salt crystallisation.
low and preventing the ingress of water into the hardened concrete will prevent
(Far left): Corrosion of steel reinforcement is a major cause of concrete deterioration, particularly in harsh coastal environments.
GLOBAL EXPERTS PRESENT PIGMENT SEMINARS Two global experts on pigment dosing and
and the manner in which these factors
versal System for pneumatic transfer of
dispensing, Hans J de Witte, a world-
can be controlled.
powder pigments in 2004.
leading specialist in inorganic pigments
Finke, who has worked with the con-
One of its more recent innovations
and Michael Finke, managing director
crete industry for 30 years, covered
is a water-soluble bag, UniPac, which is
of Finke Dosiertechnik GmbH, Germany,
some of the latest developments in
produced from water-soluble film. The
gave a seminar on pigments and advanced
Finke pigment handling systems and
bag is filled with pigment and conveyed
colour metering systems for local pre-
the advantages of each system. He also
to the mixer, where it dissolves. This
cast concrete producers shortly after
described steps which can be taken to
makes for a very clean mixing process.
this year’s Bauma Conexpo Africa.
match existing colours and the creation
Other Finke dosing systems include the
of new colour shades.
UniGran for granules and the UniMicro
Initiated by local Finke agent Pan Mixers SA (PMSA), the seminar was held in
Family-owned, Finke Dosiertechnik is
Cape Town and Johannesburg and was
world-renowned for its innovative solu-
for very small doses. The Finke factory is based in Detmold,
jointly hosted by PMSA and the Concrete
tions for dosing and dispensing powder,
close to Hanover, and was founded by
Manufacturers Association NPC.
granular and liquid pigments, chemical
Finke’s father in 1985. It is run by
De Witte, a chemical engineer with
admixture sealers and other materials.
Michael Finke and his brother, Ingo,
40 years’ experience in concrete pig-
The company is highly innovative and
employs 40 people and sells its dosing
ments, coatings and concrete produc-
was responsible for inventing the Uni-
tion, was technical service manager at one of the world’s largest inorganic pigment manufacturers, where he ran the inorganic pigment laboratory for the construction industry. His pr esenta tion de f ined colour and how to produce coloured concrete products more effectively. He reviewed the spectrum of pigments available for colouring concrete, illustrated their inherent advantages and described the f actor s which af f ect colour in cementitious pr oducts and how to ma t ch them . He also c o v er e d the advantage of using sealers and explained how raw materials, mix designs and processing conditions can affect colour
PRECAST | ISSUE TWO | 2018
(Above): The Cape Town pigment seminar participants included (from left): Roann Heunis of Chryso, Abdul Galiek of Wondercrete, Peter Visser of CEL Paving Products, Simamkele Ngcaba of Cape Brick, Ben Punt of DBL Precast Decking, Bartlett Barnard of Van Dyk Stene, Michael Finke of Finke Dosiertechnik GmbH and Hans J de Witte, chemical engineer and international pigment expert.
gel that results in the concrete cracking.
ADMIXTURES’ ROLE IN MEETING STRICT What exactly are admixtures? Basically, they’re chemicals used to modify and enhance concrete’s freshly mixed, setting or hardened properties. They’re added to the batch before or during mixing. What led to admixtures’ development? There’s been a change in building practice over the past few decades, with more expected of concrete than ever before.
REQUIREMENTS FOR CONCRETE Just how important are admixes in the manufacture of quality concrete products? Norman Seymore, head of admixture producer, Chryso Southern Africa, explains the role of admixtures in concrete design
The trend now is to use fluid concrete that
What are the main categories of admix-
When did the construction industry be-
can be fitted and moulded into any shape.
tures used in concrete mixes today?
come converted to the role admixtures
However, concrete strength is non-
Admixtures can be classified into five
can play to enhance performance and
negotiable and that’s why chemicals such
main categories: plasticisers, super-
durability? Was there substantial early
as admixtures were developed: to enhance
plasticisers, air-entrainers, accelerators
concrete without sacrificing strength.
It was during the 1980s that admixtures
How do admixtures improve concrete
Briefly, what are the individual charac-
essential part of concrete mix design.
teristics of these admixtures?
In the early years, there was scepti-
Admixtures can improve workability,
When plasticisers are added to the con-
cism from some quarters, but as the
develop high early strength, increase
crete mix, they enhance workability by
industry’s advanced – and become able
ultimate strength, compensate for
repelling binder particles and distribut-
to really measure the benefits of admix-
temperature fluctuations and improve
ing the particles more evenly throughout
tures – there are very few projects on
resistance to corrosion, shrinkage or
the concrete. Super-plasticisers can re-
which admixtures aren’t included in the
freezing and thawing. They’re also used
duce the required water content of the
concrete mix design today.
to overcome placement emergencies
concrete mix by 15-20%. Air-entrainers
such as equipment failure and other un-
introduce bubbles to the concrete mix
Is there a facet of the construction op-
expected delays. Admixtures also reduce
to provide maximum protection against
erations that particularly benefits from
the cost of the concrete mix and com-
f r eezing and thawing and incr ease
the use of admixtures in the concrete?
pensate for poor aggregate properties.
workability when the mix lacks fines.
Many precast operations now use self-
Accelerators speed up the chemical
compacting concrete (SCC). This is a
reaction of the cement and water and,
highly flowable type of concrete that
consequently, the rate of hydration,
spreads into the form without the need
really started to be regarded as an
“The new-generation admixtures are based on specific raw materials or polymers (polycarboxylates).”
improving the setting or early gain in the strength of concrete. Retarders, on the other hand, slow the chemical reaction of cement and water, providing longer setting times and slower initial strength gain.
(Top, from left): Evaluation of the alkali content of cement and admixtures by Donald Khoza in the Chryso Centre of Excellence laboratory, which provides a testing and advisory service to customers; the towering pylons of the Nelson Mandela Bridge in Johannesburg were filled with self-compacting concrete based on an admixture supplied by Chryso.
PRECAST | ISSUE TWO | 2018
of admixtures not only in this country,
admixtures are used to meet a project’s
segregating concrete that’s placed by
means of its own weight.
The new-generation admixtures are
With careful mix design, SCC admix-
based on specific raw materials or
How important are the advisory role
tures produce a concrete that’s fully
polymers (polycarboxylates). These raw
and after-sales service in the admixture
flowing and self-compacting and can be
materials and formulations radically im-
placed with no vibration. SCC functions
prove the performance of the admixture
Accurate dosing is essential to fully
in the same manner as super-plasticised,
in terms of water reduction/workability
capitalise on the benefits of admixtures.
flowing concrete, but doesn’t need any
retention and strength development,
Dosage rates and admixture selection
compacting ef fort. It’s also
compared with traditional or
are determined through a series of trial
less susceptible to bleed and
old-generation admixtures. A
mixes to optimise concrete properties.
key benefit for Chryso is that
This is why it’s vital for suppliers of ad-
A dmi x tur es, speci f icall y
we produce our own raw mate-
mixtures to provide detailed guidelines
rials for the formulation of our
to assist with design of mix proportions
fluid SCC, which is cohesive
and admixture dosages.
Which sectors of the construc-
cerned, Chryso recently substantially
tion industry are the main us-
expanded its laboratory testing facilities
with high flow retention. SCC is also extremely pumpable. For example, the towering pylons
As far as after-sales service is con-
of the Nelson Mandela Bridge in Johan-
ers of your admixtures?
with the opening of a new Centre of Ex-
nesburg were filled with SCC based on
Ready-mix concrete users mainly use
cellence in Jet Park. The centre features
a super-plasticiser supplied by Chryso.
admixtures to adjust the workability
ultra-modern equipment and temperature
retention of concrete; precast users
control systems to offer cement, concrete
What exactly is new in Chryso’s New
use admixtures to speed placing and set-
and construction system technology as an
Generation range of admixtures, which
ting times so that they can get faster
added-value service to customers.
have been around for a few years now?
turnaround time of the moulds and im-
And how radically did these relatively
proved surface finishes, while for on-site
“green” chemicals change the fortune
mixing for new construction, different
(Above): Admixtures were developed to enhance concrete performance without sacrificing strength, says Chryso chief Norman Seymore.
for mechanical vibration. It’s a non-
PREVENTATIVE MAINTENANCE ENSURES DURABILITY The durability of concrete structures, in-
especially in zones where chloride ingress
cluding precast, can be greatly increased
or carbonation are a reality. Repairing
“Among the most common challenges of
by a proper preventative maintenance and
deteriorated concrete and restoring its
concrete rehabilitation are crack repair,
repair programme, says Warren Trew,
structural integrity should consequently
patching, using strengthening methods
Gauteng sales manager: General Con-
form part of the initial design, but these
(in lieu of repair) like carbon fibre plate or
struction of abe Construction Chemicals.
measures are frequently resorted to only
wrap, and generally choosing the most ap-
when emergencies arise.
propriate repair materials for an effective
Trew says many key South African building and civil structures have eroded
“The first and most crucial step in
long-term solution. A decision should also
with age, neglect, misuse, weather fac-
a successful repair project involves
be taken on whether strengthening meth-
tors, rebar corrosion, extraneous load-
early damage assessment and arriving
ods should be opted for instead of repair.
ing and natural disasters. “Neglecting
at a proper diagnosis. The
Fortunately, the range of con-
the need to introduce proper repair and
owners shouldn’t wait until
crete repair products avail-
maintenance systems for these struc-
the concrete shows obvious
able today have made it pos-
tures results in reduced capital value and
signs of distress. To properly
sible to economically refurbish
wastage of resources, which could lead to
repair any damage, it’s im-
structures that just a few
poor quality of life for communities. With
portant to understand what
decades ago would have had
large parts of SA currently experiencing
c ause d th e p r ob l em an d
to be demolished and rebuilt.
devastating drought, the need for ad-
then determine the correct
The input from specialists in
equate maintenance of water reservoirs
method of repair.
concrete rehabilitation – and
and dams particularly comes to mind.
“Experience is vital for
the selection of the correct
“In a sustainably built environment,
the diagnosing and planning of concrete
products – will avoid common pitfalls of
structural maintenance is non-negotiable.
repairs. While a high level of expertise
concrete repairs,” observes Trew.
As soon as a concrete structure is
goes into concrete construction, the
He says abe Construction Chemi-
completed, the need for a maintenance
skills, understanding and experience
cals’ range of concrete repair products
programme must start. Maintenance
required to repair damaged or deterio-
is based on epoxies, synthetic resins,
shouldn’t be driven simply by the need to
rated structures are decidedly differ-
silanes and cementitious materials. Ap-
correct defects that occur over time,
ent from those required to build new
plications include flexible slurries and
but to avoid these defects in good time,”
structures. That’s why it’s important
coatings for protecting and waterproofing
to consult reputable suppliers of con-
the concrete parts of bridges, silos, build-
crete repair products – companies that
ing and water containment structures
can offer not only the product, but also
against attack from their environment.
He says concrete is a durable, but not
advice on its suitability, as well as the
eternal material. Over time, it will deteri-
system and procedures to be followed
orate and require repair or replacement,
for concrete repair projects.
(Above): Repairing deteriorated concrete and restoring its structural integrity should form part of the initial design, says abe’s Warren Trew.
PRECAST | ISSUE TWO | 2018
ADVANTAGES OF PRECAST CONCRETE WINGWALL UNITS Precast concrete products offer many advantages and Rocla’s precast concrete wingwall units are no exception. Wingwall units are used at both the inlet and outlet of a pipe system in both culvert and stormwater applications. Precast wingwall units offer the client a faster installation time, reduced material usage and no site-mix concrete or reinforcing on site, resulting in project cost-efficiencies. The natural flow path of water upstream of a construction is wider than the culvert or pipe structure. Transition sections are therefore required to receive and direct the flow of this upstream water through the culvert/pipe. This is also true of the downstream end of the culvert/pipe, where the flow of water is to be returned to the natural width of the stream. Where water velocities reach up to 4m/s and above, the precast concrete wingwall unit is the most effective structure to use for the transfer of this water. In stormwater applications, the primary focus is to direct water into a flow path that results in the least amount of turbulence. This, in turn, optimises the hydraulic capacity of the conduit. The wingwall portion directs the water, while the wingwall, floor slab and toe provide protection for the embankment and surrounds against scouring and possible collapse. Rocla’s precast concrete wingwall units offer: • Fast and easy installation. • A reduction in the quantity of materials required. • No waste or clean-up required. • No formwork. • Making remotely located sites simpler to manage. • Guaranteed concrete strength. • Guaranteed quantity and positioning of designed reinforcing. • No curing of concrete or formwork stripping required,
thus saving time.
• Units capable of fitting a wide range of pipe diameters
and culvert sections.
• Lifting anchors cast into the structure. “We believe that the time- and cost-savings associated with the utilisation of precast concrete wingwall units can be enormous for infrastructure-related projects. The full range of wingwalls can be manufactured at all Rocla factories nationwide, optimising transportation costs. Rocla’s well known for its manufacturing capabilities and quality standards, in addition to its technical team available to assist with technical support required by the customer,” says Justin Kretzmar, Rocla’s sales engineer. Rocla has been supplying precast concrete products to most of the major infrastructure projects in SA, Mozambique, Namibia and Botswana. Its entire product offering is manufactured to the ISO 9001:2008 standard at various plants throughout SA, Namibia and Botswana.
PRECAST | ISSUE TWO | 2018
Part of the process involved the assembly of two small desalination plants on the False Bay coastline, which used precast concrete collars for attachment to inlet and outlet pipes. The weight of the collars, which were manufactured under extremely tight time
constraints by CMA member Concrete
CONCRETE COLLARS FOR DESALINATION PLANTS Precast concrete has played a crucial role in assisting Cape Town implement emergency measures to alleviate the city’s unprecedented water shortage.
Units, provided the pipelines with the re-
positioning of the 100m sections and
quired ballast and stability to keep them
the connecting required excellent co-
firmly anchored to the seabed.
ordination and could only be undertaken
Concrete Units manager Brian Cook
during calm seas.
says that due to the pressing nature of the projects, there was very little time
to tender for and execute the contracts.
The outlet (or brine pipe, as it is called) is considerably shorter at 250m and has
a narrower diameter of 350mm. This is
“Our delivery targets were extremely
due to the fact that roughly 55% of the
challenging and, in meeting them, we
intake volume is retained and only 45%
redesigned the shape and size of the
of the original volume is returned to the
collars. This enabled us to produce fully
sea. Nevertheless, the assembly of the
workable moulds using our own technolo-
brine pipe sections followed the same
gy within seven calendar days of receiving
production process used on the Gordon’s
the order – something which has never
Bay pier and by the time the contract
been achieved before and which none of
had been completed, Concrete Units had
our peers believed was possible.
delivered 128 collars for the inlet pipe and 19 collars for the outlet pipe.
“We bent plates and took other extraordinary measures to produce
Cook says that the first cast began
the moulds in record time without any
at 6am and the second star ted at
outside help. In addition, other steps to
4.30pm. “We required a strength of
increase the rate of production included:
18MPa to remove the units from the
creating an extra week’s production by
moulds, which meant that we achieved a
working on the last three weekends be-
final strength of 70MPa, far higher than was actually required.”
fore the December holiday break, casting twice a day and using special concrete and acceleration systems.”
(Above, from top): Concrete collars on the pier at Gordon’s Bay prior to the assembly process; two pipe sections are butt-welded together.
These desalination plants are regarded as short-term emergency measures and are due to be decommissioned
Using mobile and containerised desalination equipment from Europe, the
15km to a barge 1,5km offshore of the
after two years in operation. This is due
first plant was installed at Monwabisi off
to the fact that desalination is energy-
Baden Powell Drive, which links Stellen-
Each pipe section was hauled inland by
intensive, very expensive and decidedly
bosch to Muizenberg. With a daily output
a winch and, once in position, was flooded
non-eco-friendly. After decommissioning,
capacity of seven megalitres, the plant is
and guided to the seabed by professional
the concrete collars will be recycled. The
linked to the sea via two separate pipes.
divers. The divers also did the final con-
steel will be separated from the concrete
nection on the seabed by bolting the
and recycled and the concrete will be
flanges of each section together. The
crushed and sold for use as sub-base
Clean water The inlet pipe has a diameter of 630mm
material. The HDPE pipes will either be
and extends 850m out to sea. It was
redeployed as pipes or recycled. Very
assembled off-site by the main contrac-
little will be wasted.
tor, Subtech, in Gordon’s Bay harbour in 100m lengths using 12m HDPE pipe sections. This involved welding the pipes together on the pier and then fitting the collars around the pipes at 6m intervals. Once a 100m section was assembled, it was capped at either end to trap the air inside so that it could float. Cranes were used to launch completed sections off the pier into the water and a tug towed two sections at a time some
(Left): A floating pipe section with concrete collars attached. (Above): A 100m pipe section is attached to a tug prior to towing out to sea.
PRECAST | ISSUE TWO | 2018
AFRICAâ€™S MOST SOUTHERLY ROAD PAVED WITH EXPOSED AGGREGATE CBP Exposed aggregate concrete block pavers (CBP) have been used to pave a section of road which runs parallel to the Western Cape coast between the Cape Agulhas lighthouse and the coastal village of Suiderstrand. Situated in the Agulhas National Park on the southernmost tip of Africa, the road was constructed for the SA National Parks Board (SANParks) during the latter half of 2017 and early part of 2018. The paved section extends 1,2km across gently undulating topography from the lighthouse to a new outdoor museum which was recently built to commemorate this unique geographic location. The road has a paved width of 6,8m and was paved with 8 100mÂ˛ of 70mm Muddy exposed aggregate interlocking paving blocks, manufactured by CMA member CEL Paving Products. SANParks specified that the road should make as little visual impact on the surrounding topography as possible. This was achieved by giving the road a low profile and using a paver which blends in with the colours of the sand and rocks of the region. Designed by consulting engineers Ingerop SA as a cambered road with cross-culvert drainage, it was constructed by grading and compacting an existing gravel road. The sub-grade, which was formed with material from the existing road, was covered with a sub-base of imported G5 aggregate, cementstabilised to a C4 quality. Excavated material was used to form a berm on the landward side of the road, which was heaped above road height to channel stormwater away from the road and into the cross-culverts. The project also involved precast concrete kerbing, the construction of 1,0m-deep mole barriers using 2mm-thick HDPE sheeting and a raised pedestrian crossing which links a boardwalk between the lighthouse and the open-air museum. The paving contractor was Mapitsi/Masiqhame Joint Venture, which used local labour to lay the pavers in a herringbone pattern. The concrete kerbs were supplied by Blueportwetcast based in Eersterivier.
PRECAST | ISSUE TWO | 2018
CMA member Rocla is undertaking several large-scale sewer and stormwater projects with some challenging requirements along the way. In Waterkloof Quarry, a 58ha landmark
situated on the border of Waterkloof Ridge and Monument Park, Rocla was selected to manufacture and supply all the stormwater (spigot and socket) and interlocking pipes for an upmarket retirement estate known as the Waterkloof Marina Retirement Estate, due to be launched early in 2019. Hannes Bezuidenhout, estimator from Advance Projects, comments: “This exciting development will consist of a mixed-use development which will offer a large selection of sectional title and full ownership retirement units and full support facilities, such as a 24-hour
DIVERSE PROJECTS FOR
I believe the Waterkloof Dam’s still good
for bass fishing!”
ability, that secured it the contract to
for the delivery of our large stormwater
supply over 614 assorted stormwater
pipes, so that no major inconvenience or
pipes and fit in with the project’s six-
disruption to excavation scheduling oc-
“However, it wasn’t without its chal-
curred. I believe Rocla successfully met
frail care centre, medical centre, restaurants and recreation facilities. And
these specific challenges,” says Brendon
lenges. The size of the pipes required
van Vuuren, sales consultant for Rocla.
for the development and proximity of
the pipe trenches to existing roads
“Obviously, when there are existing
Rocla’s spigot and socket storm-
created some logistic issues in terms
roads nearby or trench excavation work-
water pipes use the rolling rubber ring
of excavation materials, pipe deliveries
ing space is small, the delivery of large
principle and no lubricant is required.
and existing traffic flow.
stormwater pipes can be problematic
Pipes within this category may be or-
for contractors at site.
dered as both stormwater culvert (SC)
“Rocla understood these issues and ensured that pipe deliveries were as we
“At the Waterkloof Marina Retire-
or stormwater and irrigation (SI) pipes.
requested and that pipes were offloaded
ment Estate project, these factors
SI pipes are hydrostatically tested after
as close to the excavated trenches as
needed to be addressed, particularly
possible for ease of installation,” says Bezuidenhout. “The timeframe for pipe delivery was a mere three months and it was Rocla’s capability to meet this timeframe, its competitive pricing and product avail-
“The timeframe for pipe delivery was a mere three months.”
Sewer augmentation The increase in residential and commercial developments in the Walmer area of Port Elizabeth, in addition to the estimated increasing requirement by 2020, was a crucial factor for the Nelson Mandela Bay Municipality to increase the capacity of the existing Driftsands Collective Sewer Augmentation. The construction of a 1 400mm concrete high-density polyethylene (HDPE)lined sewer of 1 850m in length forms part of Phase One of this four-phase project, which commenced in the second quarter of 2017. Rocla was selected
(Above): Sewer pipe laid on stone bedding for the Driftsands Collective Sewer Augmentation. (Left): Rocla pipes ready for transport.
PRECAST | ISSUE TWO | 2018
and continued with production for the
come the accepted and required stand-
and manhole access pipes. The sewer
remainder of the year. Ten manhole ac-
ard for all future outfall sewer projects.
star ts f r om the Drif tsands Waste
cess pipes were also ordered and these
Water Treatment Works and terminates
were cut in the Rocla yard to specifica-
at the ACSA boundary.
tion, which allowed the laying of pipes to
“With Phase One completed, the sec-
The existing sewer was constructed
continue uninterrupted, thus giving the
ond phase is due to start during 2018,
in 1983 and is a gravity sewer which is
contractor the opportunity to achieve
which will certainly present Rocla with
unable to be upgraded from a technical
good production on site.”
new and interesting challenges, as the
perspective, so a realignment of the line
conditions include rock and very deep
route is currently being undertaken. The
trenches, but we’re more than confident
first 1 460m is parallel to the existing
in our ability to overcome these, as well
1 050m Driftsands Collector sewer and
as in our manufacturing capabilities,”
then branches off to bypass the planned
ACSA extension of the Port Elizabeth
to supply Class 75D HDPE-lined pipes
The value of the Phase One project is
R52,8 million and consists of 1 850m of 1 400 concrete HDPE-lined sewer pipes,
26 manhole structures, one diversion
Graham Howell, Rocla sales consultant
chamber and bulk earthworks.
in Port Elizabeth, explains: “We started
On completion, the 4,2km four-phase
manu f ac tur ing the 780 leng ths o f
project will have addressed the sewer-
1 400mm diameter Class 75D HDPE-
age requirements for existing and future
lined pipes in May 2017 at an average rate of eight pipes per day. We achieved this by double-stripping our four available moulds and we delivered the first
developments for the western suburbs (Above): Pipes being installed at the new Waterkloof Marina Retirement Estate.
Rocla made further design changes
of the Nelson Mandela Bay Municipality. Calling municipalities
during the manufacture of the manhole
Effective stormwater management can
“We made minor improvements to the
rings and offered rings and cover slabs
prevent pollution, flooding, erosion and
product after numerous on-site visits
with internal HDPE liners. This could be-
damage to the environment and infra-
pipes to site in July 2017.
We are there when you repair
Need to maintain your concrete? Our Information Centre has extensive information on assessment and repair techniques. Improve concrete with us. www.theconcreteinstitute.org.za +27 11 315 0300
structure. It therefore makes financial
potentially threatening pollutants into
Projects from Mozambique to Cape Town
sense for local municipalities to invest in
local rivers, dams and municipal water
have utilised technical support and prod-
products and technologies to ensure that
services, creating a breeding ground for
uct quality that is associated with the
the quality of infrastructure, be it stabil-
diseases that could seriously affect the
ity or sustainability, of both the built and
health of humans and livestock.
natural environments is not compromised.
Rocla has been contracted for the
Storms and the resulting floodwater
supply of precast concrete storm-
Rocla’s stormwater pipes with both in-
can carry toxic particles such as oil, pes-
water pipes to numerous projects over
terlocking and spigot and socket joints
ticides, pet waste, fertiliser and other
the 100 years it has been in operation.
are available in a range of strength
ratings. The spigot and socket joints utilise the rolling rubber ring principle, where no installation lubricant is required. All pipes conform to the SANS 677 standard. Af ter consultations with Rocla’s technical team, interlocking joint pipes were selected for installation at the Great North Plaza in Limpopo, while the Borwa project in Westonaria selected Rocla spigot and socket joint stormwater pipes. Technical support from Rocla ensures that correct product and technology is selected with consideration for the financial constraints of each project. Rocla’s entire product of fering is manufactured to the ISO 9001:2008 standard at various plants throughout SA, Namibia and Botswana.
NEW 3D PRINTED HOUSE Arup and CLS Architects unveiled 3D Housing 05 – a new 3D printed house in central Milan – as part of the Salone del Mobile design festival. Printed on-site by a portable robot, the house showcases the role 3D printing can play in reducing construction waste; it increases efficiencies during the building process and allows materials to be re-used at the end of the building’s life, rather than ending up as landfill.
the end of their lives. 3D printing technology is critical to helping our industry become far more accurate, efficient and less wasteful.” “This building represents a milestone for 3D printing applied to construction,” says Luca Stabile, Italy building practice leader at Arup. “The industry’s fast moving towards increased levels of automation. Robots are opening up a number of possibilities for realising
The construction industry is currently one
the next generation of advanced build-
Advantages of 3D-printed buildings
of the world’s biggest users of resources;
ings. Digital tools combined with new
• Sustainability: They of fer a
in the UK alone, it accounts for 60% of
technologies will enable the production
sustainable alternative to the
all raw materials consumed. The concrete
of custom-made shapes that can’t be
traditional construction pro-
3D-printed house, the first of its kind
produced otherwise. We’re pushing the
cess, reducing material waste
within the EU, can be taken apart and re-
boundaries and contributing to radical
and allowing recycled concrete
assembled elsewhere. Arup, a knowledge
innovation through new manufacturing
to be used. 3D-printed buildings
partner of the Ellen McArthur Foundation,
technologies and materials.”
can be designed to ensure that
has applied learnings from its innovative
A robot from Cybe Construction was
the components can be re-used
Circular Building, which was constructed
used to print the walls, while the roof,
in the future, according to the
out of fully re-usable components.
windows and doors were completed af-
principles of the Circular Economy.
T he one-stor ey concr ete house,
terwards. Italcementi, one of the world’s
• Flexibility: They also offer great-
located in the grand Piazza Cesare Bec-
largest cement suppliers, provided advice
er f lexibility in the building
caria, covers 100m2; it has curved walls,
for the base concrete mix used during the
shape, allowing engineers and
a living area, a bedroom, a kitchen and a
architects to generate more
bathroom. The project differs from many
complex structures, such as
other 3D processes in its use of a robotic
double-curved walls, at lower
manipulator, mounted on a movable base
cost. In addition, the process
for increased flexibility compared with
allows for on-site construction
fixed 3D printers. The house is made up of
with few limitations regarding
35 modules that have each been printed
in 60-90 minutes; the full house has been
• Affordability: 3D printing is less
printed in just 48 hours’ effective time.
expensive than traditional con-
The building will be moved from the square
str uc tion due to the mor e
to a new location after the festival.
efficient use of materials and
“We’re at Salone del Mobile to build
a more structured and faster
momentum,” says Guglielmo Carra, Eu-
rope materials consulting lead at Arup.
MOULDS STEEL FIBREGLASS POLYURETHANE SILICONE
• Accuracy: 3D printing offers a
“We need to make a major shift in the
dir ect transf er of inf orma-
way the construction industry oper-
tion from the 3D design model
ates, away from today’s ‘make, use and
to construction operations,
dispose’ mentality. We’ve shown with
082 774 4657 Unit 8, Ken Smith Industrial Park, Rand Street, George Industria
thereby drastically reducing
this building that 3D printing technology
building inconsistencies and
is now advanced enough to take on more
complex structures and we can design buildings to be re-purposed or re-used at
PRECAST | ISSUE TWO | 2018
The channel forms the major component of a sustainable urban drainage system (SUDS) designed to protect the new housing estate from water flows during heavy downpours. Specified by the Western Cape’s Provincial Government, it was designed by consulting engineers
Over 76 000 precast concrete Terracrete grass blocks, manufactured by Terraforce licensee and CMA member, Klapmuts Concrete, have been used to line a 6,5m-wide section of 1,8km stormwater drainage channel next to what will become the Vlakkeland low-cost housing estate in a peri-urban area on the outskirts of Paarl, Western Cape.
Lyners & Associates, based on input from Guillaume Nel Environmental Consultants and some initial stormwater surveys undertaken by Graham McGill of Graham McGill Consulting. T he channel is par t of a system which has been designed to ensure that stormwater flows are managed and dispensed in a controlled manner. Several tributaries and stormwater pipes which previously flowed into several evaporation ponds, situated on the land earmarked for the new housing estate, now drain into the main channel, Channel 1, and into two tributary channels, named 2 and 3.
PERMEABLE GRASS BLOCKS USED FOR
MASSIVE STORMWATER CHANNEL Water management
to minimise dust during dry periods and
The unlined section of the main channel
encourage water infiltration.
was designed to accommodate a 1:100
The main channel is composed of four
year flood (50,2m³/s), whereas the lined
material layers: the sub-soil which was
section can accommodate a 1:5 (18m³/s)
compacted with rollers to 93% MOD
AASHTO, a layer of Grade A2 geofab-
The deployment of the Terracrete
ric, which prevents the blocks from
blocks and mini gabion dams, which were
settling too much and allows filtration,
built into the downstream section of
while preventing the wash-out of locally
Channel 1, reduce flow rates and allow
sourced bedding sand, and the Terra-
the SUDS system to better filtrate any
crete grass blocks.
run-off. The other major component of
These Terracrete blocks are being
the system is a large attenuation pond
filled with a bio-charcoal material and
which was excavated at the bottom end
mushroom spores, the former to absorb
of Channel 1.
pollutants in the water and the latter
The pond further reduces the flow
to recharge the charcoal and keep it fit
rate and prevents surges by releasing
for purpose. The channel banks above
water gradually through a 450mm outlet
the blocks are being planted with grass.
pipe at the far end of the pond. However,
The main channel and the bulk earth-
when water volumes are such that
works, including the attenuation ponds
the pond fills to capacity, the overflow
and other channels, were constructed
pushes back into the main channel at the
by JVZ Construction.
entrance to the pond. Absorbing pollutants In addition, a secondary and smaller attenuation pond has been excavated immediately above some culverts which have been installed under a main tarred road adjacent to the estate. Grass has been planted on the floors of both ponds
(Top): The lined section of Channel 1 under construction. (Left, from top): The partially completed Channel 1 in which the bio-charcoal fill material can be seen inside the Terracrete blocks; newly-laid Terracrete grass blocks in Channel 1; the main attenuation pond under construction; the partially completed entrance to the main attenuation pond where Channel 1 forks, one arm leading into the pond and the other feeding into an extension of the channel.
PRECAST | ISSUE TWO | 2018
CONCRETE CAST STONE COBBLES UPGRADE WINE ESTATE HOUSE Situated on the Libertas Wine Estate in
Stellenbosch, House Van Heerden underwent wide-ranging renovations during the second half of 2017. The project involved a complete redesign of the garden, which was wild and hilly, and extensive use was
because the house was to be painted
forecourt also included a grass block sec-
made of CMA member Revelstone’s char-
white and because the roof and window
tion, adding colour diversity and softening
coal Kent and Jura cobbles, in combina-
frames were also coloured charcoal.
the whole area.
tion with Ravine tiles and pavers.
Moreover, as Tone Alexander explained,
Further design differentiation was
charcoal provided an excellent backdrop
achieved by paving a patio and a section
to green foliage.
between the driveway and front door,
The design of the new paved areas involved collaboration between the landscape designer, Tone Alexander Design
Kent and Jura cobbles were used to
with larger Ravine tiles in the same char-
Solutions and paving contractor, Adrien
good effect on the large driveway and
coal colour. Other paved areas included
of Progressive Paving, and it included
forecourt in front of the house. They
the courtyard and kitchen patio.
repaving the original red brick driveway
were laid in grid formation together with
in Kent and Jura cobbles.
rectangular Jura cobbles, which were
Char coal cobbles wer e specif ied
used as edging and accent lines. The
(Above): Revelstone’s Jura and rectangular cobbles form the perfect contrast to the green foliage in the forecourt of House Van Heerden.
granite inlays per square metre of paving. Paving contractor Cox Civils did this by cutting into and removing the middle section of G-Bloks and inserting granite block pieces between the remaining two pieces of G-Bloks. The G-Bloks were supplied in thicknesses of 80mm and 60mm, the former for areas of heavy traffic and the latter for light-trafficked areas and walkways. In addition, Aveng Infraset supplied
EXPOSED AGGREGATE PAVERS FOR SUPERIOR PAVING FINISH
12 000m² of 60mm grey G-Bloks for the
In what may well be a first for SA, just
paving gives an established look which im-
designed by Craft of Architecture. Apart-
under 3 000m2 of exposed aggregate
proves with weathering, a process which,
ments are being marketed from R1 million
paving blocks have been used in combina-
over time, renders the jointing invisible.
for a single-bedroom unit and up to R3,7
tion with polished granite inserts for the
Another plus was that Aveng Infraset’s G-
million for a three-bedroom unit. Luxury
paving of parking areas and driveways
Blok pavers passed all engineering tests.
four-bedroom units are also available.
at OceanDune Sibaya, a 260-unit luxury
Uys & White also suggested the use
Occupation of OceanDune Sibaya
apartment development some 10km
of granite blocks for enhanced aesthetic
began at the end of May this year and
north of Umhlanga Rocks, close to the
appeal and their glitter effect at night
final occupation will take place at the
Sibaya Casino on the KwaZulu-Natal
and specified the insertion of roughly four
end of August, when further units are
(KZN) North Coast.
paving of the parking basements. OceanDune Sibaya is being brought to market by Construction ID and was
completed. A neighbouring development,
The paving, which comprised CMA
Pebble Beach, which is also being devel-
member Aveng Infraset’s exposed ag-
oped by Construction ID, is earmarked for
gregate G-Blok paver, was specified by
completion by mid-2019.
Uys & White Landscape Architects KZN. The inspiration came from the exposed aggregate paving used in the parking areas of Cape Town’s Kirstenbosch National Botanical Garden. Exposed aggregate
PRECAST | ISSUE TWO | 2018
(Above): A newly-completed section of exposed aggregate paving at OceanDune Sibaya. (Left): Polished granite blocks are installed between exposed aggregate G-Blok pavers at OceanDune Sibaya.
CAPE TOWN LUXURY HOUSING UNITS BUILT WITH PRE-STRESSED RIB AND BLOCK DECKING Due for completion in April 2019 and varying between 250-340m², the triple-
storey houses comprise four-car basement garages and luxury finishes, as well as eco-friendly features such as watersaving devices and integrated heat pumps combined with solar panels, among numerous other options. Priced between R7,95 million-R8,95 million, five units had been sold as Precast went to press. The R&B system was supplied by Western Cape-based DBL Precast Decking. Manufactured in standard 150mm widths and 60mm depths, the ribs were pre-stressed and came in lengths of 1,27,5m. A Classico Developments project, 3 Mona is being constructed by main contractor WJC Projects, which has been using R&B construction for the past 15 years. WJC managing director, John Watson, notes that the major advantages of R&B over pure in-situ construction
A new triple-storey cluster housing project, 3 Mona, situated in a secure residential estate near Cape Town’s Newlands cricket ground, is being built using prestressed concrete rib and block (R&B) decking.
are speed, price and simplicity. Fast erection “A 100m² deck, including the propping and all the servicing and reinforcing, takes us three days to install before the concrete is poured and it took us a mere eight weeks to cast all 18 decks on this project. 3 Mona’s completed slabs are 300mm thick and once the concrete had been poured on the R&B formwork, it was only a matter of days before we were able to begin work on the upper-storey structures,” says Watson.
of mesh with the engineer’s consent, but
“We’ve been using a combination of
we prefer mesh because it can be used to
100mm-, 150mm- and 200mm-high deck-
keep conduits in place and prevents them
ing blocks to achieve various deck depths.
from floating up during casting.”
The low 100mm block is very useful to accommodate services within the depth
of the slab without compromising its
DBL has been in the R&B business since
structural integrity. It’s also used where
1986 and has worked solely with inde-
bottom reinforcing, such as transverse
pendent consulting engineers on all its
stiffeners, is required.
(Top): Y32 rebar was used in the construction of small cantilevered balconies outside the main bedrooms on the second-floor decks. (Above, from left): The underside of a second-floor structure at 3 Mona, showing the steel support beam as well as the R&B assembly; a recently installed floor showing Y16 rebar stiffeners laid down the middle of a second-floor deck at 3 Mona. Also visible are 6mm hard-drawn loop-shear connectors, which are cast into the ribs to anchor the poured concrete to the R&B assembly.
projects. This is one of the reasons there
slabs. In this instance, the project engi-
“Ribs contain all the primary bottom
are very few engineers in Cape Town who
neer, Ted Kelly, made good use of R&B’s
reinforcing for the decks. This is why engi-
do not have considerable experience in
versatility to overcome the numerous
neers design the top reinforcing elements
R&B. All engineers have their own pref-
design challenges on these triple-storey,
such as cantilevers, continuity and hog-
erences in design and some of them are
open-plan houses. He designed the houses
ging steel, as well as transverse reinforc-
more cautious than others.
with a mix of steel and concrete beams
ing to run in the opposite direction to the
R&B can be very successfully designed
as additional load-bearing mechanisms
span of the ribs. On this project we used
to work compositely with both steel and
over large openings to transfer loads to
Ref-100 mesh as anti–cracking reinforce-
concrete beams, particularly as the depth
foundation. He also made innovative use of
ment. Fibre concrete can be used instead
of the beams is equal to the depth of the
span direction changes to accommodate
PRECAST | ISSUE TWO | 2018
traditionally reinforced lattice systems.
These include reduced long-term de-
Punt adds that pre-stressed R&B con-
Several deck sections at 3 Mona
flection, superior fire- and corrosion-
struction has a fairly green footprint
were up to 10m wide, which meant the
resistance and enhanced sheer capacity.
because it uses up to 75% less steel
spans needed to be broken by beams.
The most important factor, however, is
than traditional in-situ slabs and lat-
Although the majority of the beams on
the cost-savings, which are passed on
tice R&B slabs. And because the blocks
this project are concrete, Kelly used
to our clients.
are hollow, they use less concrete and
shallower steel beams over the open-
reduce dead weight.
plan lounge, kitchen and dining areas,
“The other big benefit of R&B is
where the architect and clients wanted
that it’s labour-intensive, both in its
uninterrupted, open soffits.
manufacture and application. Installation doesn’t require skilled labour and
can take place as soon as some of the
“A major plus of R&B construction is
load-bearing walls reach slab height. One
that it’s a hybrid system, offering the
doesn’t have to wait until all the walls
best of both worlds, precast and in-
reach slab height and because they’re
situ construction,” says Ben Punt, MD of DBL Precast Decking. “It has all the
(Above): One of the 10m steel beams which were used by the engineer for R&B support.
adaptability and flexibility that come with
easy to install, we’re finding that bricklayers can easily do the decking installation as well.
in-situ, while providing a solid composite
“We produce ribs to stock lengths
“This means the masonry work and
structure. It also provides the speed of
in 100mm increments and we always
slab work can be done in tandem. This
construction of precast concrete and
have about 15 000m² of stock ready
also gives the plumber and electrician
the structural integrity of in-situ con-
and cured, available for delivery as soon
additional time to tube the slab, prevent-
struction, due to the reinforced in-situ
as the engineer’s design has been ap-
ing a last-minute rush and subsequent
proved. This is in contrast to lattice R&B
errors. This is a convenient and flexible
“We’ve chosen to specialise in pre-
construction, where the ribs are only
way of keeping a building team on site
stressed R&B construction because
manufactured after the design measure-
all the time, which builders find very
of the undeniable benefits gained over
ments have been confirmed.”
beneficial,” says Punt.
cantilever balconies and the voids around
SAâ€™S SMART C Property development and nature might not automatically go hand in hand, but more and more developers are moving towards incorporating nature into building design. Green spaces prove popular, even in major city centres where they are seemingly rare. Rooftop gardens are springing up in central business districts in the likes of Hong Kong, Tokyo, Rotterdam and New York. Likewise, urban farming initiatives
CITIES ARE DRIVING SUSTAINABILITY makes a smart city? Combining the
opers are under pressure to drastically
perks of modern technology with the feel
minimise water usage and incorporate
In SA, Johannesburg has long been
of old-time village living – with walkable,
eco-friendly technologies that will ben-
considered the world’s largest man-
pedestrianised streets and green spaces.
efit the planet in the long term. “Modern
made urban forest, boasting more than
Yet “green can mean many things. It’s
trends in development and construction
6 million trees. And Cape Town’s CBD is
the colour you allegedly turn when you’re
are predominantly focused on issues re-
set to change with the arrival of its first
sick, envious or inexperienced. You’re
lating to sustainability,” says Stopforth.
environmentally friendly mixed-use de-
encouraged to “eat your greens” to stay
“Residents and investors want to know
velopment: Harbour Arch. Perhaps sur-
in good health. You can green an urban
what’s being done to reduce impact on
prisingly, one of the most eye-catching
area by planting trees, or even green
features of this 5,8ha mixed-use precinct
your home to make a positive impact on
will be the complex’s green roof top
to boost food resources are fast becoming a global trend.
New-urbanist pr ecincts such as
“Everything about development today
Melrose Arch and Harbour Arch revolve
is about sustainability and energy-wise
around the principle of being close to
innovation, water-saving technology,
With the rise of “smart cities” – mixed-
everything you need in daily life, with all
heat-reducing aspects, etc. And when
use precincts – developers are driven
your requirements accessible by foot.
you use sustainable technology, you also
to find ways of creating green spaces
But it’s the outdoor spaces – the piazza-
reduce the cost of occupation in the long
innovatively in a bid to bring nature to
style squares and courtyards for dog-
term and obtain a competitive edge,”
the concrete jungle.
walking or people-watching – that give
towering over the city’s harbour.
Nicholas Stopforth, managing director of Amdec Property Developments
these inner-city developments a sense of community.
Sustainability and eco-friendly innovation are a key focus area of Amdec’s developments, with green building initia-
– the group behind SA’s award-winning Melrose Arch and the new Harbour Arch
tives including refuse recycling, water-
– says green spaces are essential for
There has been huge demand for busi-
saving devices, low-energy LED lighting
people to feel safe and secure in an envi-
ness, retail and residential spaces within
and rainwater harvesting. With water
ronment. Nature has long been lauded for
Melrose Arch. So much so that a new
scarcity being the new normal for SA,
its positive impact on the human psyche.
residential complex – One on Whiteley
developers must implement water-wise
There are countless studies and reports
– within the precinct is currently under
strategies from the ground up. Harbour
on the benefits of green spaces for our
Arch, for example, has been designed to
But just what The world over, devel-
harvest rainwater to reduce the load on municipal supply. “There’s huge benefit in executing water-saving measures at the construction stage, rather than retro-fitting. Not only is it better to have systems in place at the start, but it saves money in the long run,” explains Stopforth. Recycled water – either rain-harvested or grey water – will be used for flushing, gardening and landscaping. “Ultimately, we need to reduce our impact. It’s better for business and it’s better for the planet,” says Stopforth.
PRECAST | ISSUE TWO | 2018
MEMBER LIST 44
PRODUCER MEMBERS A FICK SEMENT WERKE BK TEL: (022) 913 1921 PROVINCE/COUNTRY: WC PILLAR: PB AVENG INFRASET (PTY) LTD TEL: (011) 876 5100/872 1713/ (012) 652 0000 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI BANZI TRADE 31 (PTY) LTD T/A BRICKIT TEL: (011) 023 6708 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI BETA TILES (PVT) LTD TEL: (263) 4333735 PROVINCE/COUNTRY: ZIM PILLAR: PB BOSUN BRICK BRITS (PTY) LTD TEL: (012) 250 1711 PROVINCE/COUNTRY: NW BOSUN BRICK MIDRAND (PTY) LTD TEL: (011) 310 1176 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI BOSUN BRICK PORT ELIZABETH (PTY) LTD TEL: (041) 405 0100 PROVINCE/COUNTRY: EC C.E.L. PAVING PRODUCTS (PTY) LTD TEL: (021) 905 5998 PROVINCE/COUNTRY: WC PILLAR: PI CEM BRICK MANUFACTURERS (PTY) LTD TEL: (051) 433 4479 PROVINCE/COUNTRY: FREE STATE PILLAR: PB/PI CEMBLOCKS (PTY) LTD TEL: (014) 538 0311 PROVINCE/COUNTRY: NW PILLAR: PB/PI CIVILWORKS (PTY) LTD REAL TIME INVESTMENTS TEL: (011) 903 7023 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI CONCRETE UNITS (PTY) LTD TEL: (021) 386 1923/ (016) 362 2236 PROVINCE/COUNTRY: WC/GAUT PILLAR: PB/PI CONFRAMAT (PTY) LTD TEL: (0861) 33 5599 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI CORESLAB (PTY) LTD TEL: (087) 232 2462 PROVINCE/COUNTRY: LIMPOPO PILLAR: PB/PI COROBRIK (PTY) LTD TEL: (031) 560 3111 PROVINCE/COUNTRY: KZN PILLAR: PI DERANCO PRECAST (PTY) LTD TEL: (041) 463 3338 PROVINCE/COUNTRY: EC PILLAR: PB/PI EAGLE ROOF TILES (PTY) LTD TEL: (044) 874 0290 PROVINCE/COUNTRY: WC PILLAR: PB ECHO FLOORS (PTY) LTD TEL: (011) 668 1900 PROVINCE/COUNTRY: GAUT ECHO PRESTRESS (PTY) LTD TEL: (011) 589 8800/8899 PROVINCE/COUNTRY: GAUT PILLAR: PB ECHO PRESTRESS DURBAN (PTY) LTD TEL: (032) 947 3067 PROVINCE/COUNTRY: KZN
ENVIRO-CAST (PTY) LTD TEL: (016) 004 0018 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI KEYSTONE WALLING CC TEL: 082 850 3512 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI LATEGAN CEMENT WORKS (PTY) LTD TEL: (021) 873 1154 PROVINCE/COUNTRY: WC PILLAR: PB/PI MARLEY ROOFING (PTY) LTD TEL: (011) 316 2121 PROVINCE/COUNTRY: GAUT PILLAR: PB MOBICAST (PTY) LTD TEL: 086 111 2346 PROVINCE/COUNTRY: WC PILLAR: PB/PI MONIER COVERLAND (PTY) LTD TEL: (011) 222 7300/7334 PROVINCE/COUNTRY: GAUT PILLAR: PB MVA BRICKS CC TEL: (012) 386 0050 PROVINCE/COUNTRY: GAUT PILLAR: PI PANDA (PTY) LTD TEL: (00267) 244 2107/8 PROVINCE/COUNTRY: BOTS PILLAR: PB/PI PORTLAND HOLLOWCORE SLABS (PTY) LTD TEL: (021) 972 1111 PROVINCE/COUNTRY: WC PILLAR: PI REMACON PRODUCTS CC TEL: (011) 393 5504 PROVINCE/COUNTRY: GAUT PILLAR: PI REVELSTONE (CAPE) (PTY) LTD TEL: (0861) 173 835/(021) 761 9737 PROVINCE/COUNTRY: WC PILLAR: PI ROCLA (PTY) LTD TEL: (011) 670 7600/7634 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI SHUKUMA BRICKS (PTY) LTD TEL: (041) 372 1013 PROVINCE/COUNTRY: EC PILLAR: PB SILVERTON PRECAST (PTY) LTD TEL: (012) 804 4525 PROVINCE/COUNTRY: GAUT PILLAR: PI SMARTSTONE (PTY) LTD TEL: (011) 310 1161 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI SOUTHERN PIPELINE CONTRACTORS (PTY) LTD TEL: (011) 914 8500 PROVINCE/COUNTRY: GAUT PILLAR: PI TECHNICRETE (PTY) LTD TEL: (011) 672 1425/670 7600 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI TOPFLOOR CONCRETE (PTY) LTD TEL: (021) 951 7700 PROVINCE/COUNTRY: WC PILLAR: PB
WEST END CEMENT BRICKS (PT Y) LTD TEL: (011) 851 1005 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI ZITTLAU EIENDOMME (PT Y) LTD T/A SHUKUMA FLOORING SYSTEMS TEL: (041) 372 1933 PROVINCE/COUNTRY: EC PILLAR: PB NON-PRODUCER MEMBERS ABEL EQUIPMENT CC TEL: (044) 874 1876 PROVINCE/COUNTRY: EC BASF CONSTRUCTION CHEMICALS SOUTH AFRICA (PT Y) LTD TEL: (011) 203 2400 PROVINCE/COUNTRY: GAUT BIRKENMAYER H (PT Y) LTD TEL: (011) 970 3880 PROVINCE/COUNTRY: GAUT CHRYSO SOUTHERN AFRICA (PT Y) LTD TEL: (011) 395 9700/ (031) 564 0325/(021) 928 1660 PROVINCE/COUNTRY: GAUT/ KZN/ WC DECCAN DIE CASTINGS (PVT) LTD TEL: 91 80 28524121 PROVINCE/COUNTRY: INDIA DICK KING LAB SUPPLIES (PT Y) LTD TEL: (011) 499 9400/ (031) 700 2551 PROVINCE/COUNTRY: GAUT/ DBN ECO-MATCH (PT Y) LTD TEL: (011) 082 9864 PROVINCE/COUNTRY: GAUT ECONO CAST (PT Y) LTD TEL: (011) 662 2159 PROVINCE/COUNTRY: GAUT FIBERTEX SOUTH AFRICA (PT Y) LTD TEL: (031) 736 7100 PROVINCE/COUNTRY: KZN HAWKEYEPEDERSHAAB TEL: 00 459645 4193 PROVINCE/COUNTRY: DENMARK KERNEOS SOUTH AFRICA (PT Y) LTD TEL: (011) 444 3090 PROVINCE/COUNTRY: GAUT KOBRA MOULDS B.V. TEL: 003111 356 2460 PROVINCE/COUNTRY: NETHERLANDS MANITOU SA (PT Y) LTD TEL: (011) 975 7770 PROVINCE/COUNTRY: JHB PAN MIXERS SA (PT Y) LTD TEL: (011) 578 8700/8600 PROVINCE/COUNTRY: JHB QUANGONG MACHINES CO LTD TEL: +865 958 679 9557 PROVINCE/COUNTRY: CHINA SIKA SOUTH AFRICA (PT Y) LTD TEL: (031) 792 6500 PROVINCE/COUNTRY: KZN TECHMATIK S.A. TEL: (0048) 608 422 300 PROVINCE/COUNTRY: POLAND TERRAFORCE (PT Y) LTD TEL: (021) 465 1907 PROVINCE/COUNTRY: WC ASSOCIATE MEMBERS
VANSTONE PRECAST (PTY) LTD TEL: (012) 541 2056/1808 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI
ASPASA TEL: (011) 791 3327 PROVINCE/COUNTRY: JHB
VIBRO BRICKS & PAVING (PTY) LTD TEL: (012) 374 5533 PROVINCE/COUNTRY: GAUT PILLAR: PB/PI
BRITISH PRECAST CONCRETE FEDERATION TEL: +(44) 116 232 5170 (T) PROVINCE/COUNTRY: UK
CIVILPRO ENGINEERING SOLUTIONS (PT Y) LTD TEL: 083 226 2567 PROVINCE/COUNTRY: JHB CONCRETE SOCIET Y OF SOUTHERN AFRICA TEL: (012) 348 5305 PROVINCE/COUNTRY: PTA CPI CONCRETE PLANT INTERNATIONAL TEL: (02236) 962390 PROVINCE/COUNTRY: GERMANY ILIFA AFRICA ENGINEERS (PT Y) LTD TEL: (012) 362 1473 PROVINCE/COUNTRY: PTA JC PAVING CONSULTING TEL: (011) 431 0727 PROVINCE/COUNTRY: JHB SARMA TEL: (011) 315 0300 PROVINCE/COUNTRY: JHB SEKHUKHUNE & ASSOCIATES TEL: (012) 346 1945 PROVINCE/COUNTRY: PTA SNA CIVIL & STRUCTURAL ENGINEERS TEL: (012) 842 0000 PROVINCE/COUNTRY: PTA TACO VOOGT CONSULTING ENGINEER TEL: (012) 669 0125 PROVINCE/COUNTRY: PTA TJEKA TRAINING MATTERS TEL: (011) 665 2777 PROVINCE/COUNTRY: JHB YOUNG & SATHARIA CONSULTING CIVIL ENGINEERS TEL: (031) 207 7252 PROVINCE/COUNTRY: KZN CONTRACTOR MEMBERS BUFFALO RETAINING WALLS CC TEL: (016) 366 1801 PROVINCE/COUNTRY: GAUT DECORTON RETAINING SYSTEMS (PT Y) LTD TEL: (021) 875 5155 PROVINCE/COUNTRY: WC FRICTION RETAINING STRUCTURES (PT Y) LTD TEL: (011) 608 4321 PROVINCE/COUNTRY: GAUT POWERGATE CONSTRUCTION CC TEL: 071 603 5070 PROVINCE/COUNTRY: GAUT VALCAL INTERNATIONAL EXPORT CC TEL: (011) 867 2471 PROVINCE/COUNTRY: GAUT CEMENT MEMBERS AFRISAM SOUTH AFRICA (PT Y) LTD TEL: (011) 670 5500/5752/5972 PROVINCE/COUNTRY: GAUT PPC LTD TEL: (011) 386 9000/9091/626 3150 PROVINCE/COUNTRY: GAUT SEPHAKU CEMENT (PT Y) LTD TEL: (012) 684 6300 PROVINCE/COUNTRY: GAUT
PLEASE NOTE: The above member list was correct at the time of going to print. If your details have changed, please contact Rita at the CMA offices on tel: (011) 805 6742.
PI – Precast Infrastructure PB – Precast Building
PRECAST | ISSUE TWO | 2018
Applicable for integral or surface colouring of all types of concrete
Dare to be colourful ! Integral or surface colouring of concrete provides a mineral aspect which is rich in colours, whilst offering excelent durability. CHRYSO can meet any colour requirements with its comprehensive range of mineral pigments and its on-demand colour creation service
BENEFITS: Custom shades Resistance to UV rays Colours close to local materials A colouring laboratory at your service
IT TAKES MORE THAN CONCRETE TO BUILD YOUR VISION. HEREâ€™S TO THE BUILDER IN YOU.
Creating Concrete Possibilities