PRECAST VOLUME SIX ISSUE 1 • 2012
THE CMA – QUALITY CAST IN CONCRETE
• Concrete piping for massive infrastructure project • Extensive retaining wall project • UK flood alleviation scheme
CONTENTS
1
CONTENTS NEWS
23 SIKA SUPPLIES ADMIXTURES FOR
EARTH-CORE DAM
2
TECHNICRETE GEARED
FOR RISING DEMAND
3
CMA HOUSE PLANS NOW
AVAILABLE ON CAD
4
MAPEI APPOINTS NEW PERSONNEL
5
EASIER NAVIGATION ON REVAMPED
TERRAFORCE WEBSITE
27 ‘FUNDAMENTALS OF CONCRETE’ UPDATED
7
CMA ADOPTS FRESH APPROACH
27 FOXING EFFLORESCENCE
TO AWARDS FOR EXCELLENCE
28 CMA MEMBERS
24 CONCRETE BLOCK PAVERS –
THE PEOPLE’S CHOICE IN HEIDELBERG
25 CONCRETE SOLUTIONS FOR
UNDERGROUND CONSTRUCTION PROJECTS
26 NEW SUPER-SEALANT FROM MAPEI
8
CONCRETE TECHNOLOGISTS
NEEDED URGENTLY
11 PAVING STANDARD AMENDED 11 BIRKENMAYER APPOINTMENT
TECHNICAL NOTES 14 NEW CONCRETE BLOCK PAVING
STANDARD AMENDED
ARTICLES 12 EXTENSIVE RETAINING-WALL PROJECT
FOR NEW SHOPPING CENTRE
17 CONCRETE PIPING SPECIFIED
FOR INFRASTRUCTURE PROJECT
20 UK FLOOD ALLEVIATION SCHEME OPTS
FOR PRECAST CONCRETE ELEMENTS
APPLICATIONS 22 CONCRETE BLOCK RETAINING WALLS
PROTECT BURGERSFORT WAREHOUSE
22 PPC CEMENT USED FOR DE HOOP DAM
Our front cover shows a pipelaying operation at Waterfall City, Midrand, where close on 5 000m of precast concrete stormwater piping forms a major part of the site’s civil work. The pipes were specified by the Johannesburg Roads Agency (JRA) for what is seen as one of Gauteng’s largest infrastructure projects to date. Trench depths vary between 1.5m and 5.5m and with natural gradients as high as 1 in 20 in some places, 17 drop boxes are being built to reduce water velocities. See article on page 17.
PRECAST is the official journal of the Concrete Manufacturers Association (CMA) Block D, Lone Creek, Waterfall Office Park, Bekker Road, Midrand PO Box 168, Halfway House, 1685 Tel: +27 11 805 6742, Fax: +27 86 524 9216 E-mail: main.cma@gmail.com, Website: www.cma.org.za Publishers Isikhova Publishing & Communications PO Box 651793, Benmore, 2010, South Africa Tel: +27 11 883 4627, Fax: +27 11 883 4627 Website: www.isikhova.co.za Publisher: Andrew Meyer Tel: +27 11 883 4627, Cell 082 456 5175 E-mail: andrewm@isikhova.co.za Editor: David Beer Tel: +27 11 478 0239, Fax: +27 11 678 0254 E-mail: bigsky@ibi.co.za Advertising: Rui Chirindja Tel: +27 11 883 4627, Cell: 082 717 2851, E-mail: communications@isikhova.co.za Design, layout and production: Joanne Brook The views and statements expressed in this publication are not necessarily those of the editor or the publishers and neither he/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.
PRECAST VOLUME 6 • ISSUE 1 • 2012
TECHNICRETE GEARED FOR RISING DEMAND Production-line efficiencies combined with new quality levels mean that building-products manufacturer, Technicrete, is well placed to meet the demand from Government’s proposed spending on infrastructure. “The multi-billion rand “shopping list” announced in President Zuma’s State of the Nation address, and echoed in the 2012 Budget, is good news for the construction industry,” says Technicrete MD, Albert Weber. Technicrete is a member of the Murray & Roberts Building Products group and is one of the country’s largest producers of concrete building products, with eight strategically located manufacturing plants in Gauteng, Free State, Mpumalanga, Limpopo and North West Province. It produces an extensive range of concrete paving blocks and kerbing for heavy and light-duty roads, pedestrian routes, retaining wall systems, roof tiles, advanced erosion-protection systems, as well as mining products. Weber says Technicrete already has an impressive record in infrastructural growth, having contributed significantly to improving the quality of life for many thousands of people in rural areas. “In recent years, we have manufactured tens of thousands of paving blocks and kerbing in projects to upgrade hundreds of kilometers of roads and pedestrian routes - in some cases where no decent roads previously existed.” A feature of Technicrete’s operations - especially in rural areas – is its close collaboration with emerging construction companies, he adds. “These growing companies are benefiting greatly from Technicrete’s experience, technical know-how and training backup. We like to think of ourselves as partners in these upgrading projects, and our responsibility does not end with delivering the goods.” Discussing the Government’s latest infrastructural spending blueprint, Weber adds, “We are encouraged to hope that the Government will really make it work, and that the building and construction industry will see money flowing in to create more jobs.”
Infrastructure in action: roads ugrade at Alldays Township near Polokwane generates work for local labour.
CMA HOUSE PLANS NOW AVAILABLE ON CAD Architectural plans for the 40m² CMA
dimension is accounted for and avoids the
House are now available on CAD. CAD-
time-consuming and wasteful process of
based plans can be down-loaded off the
chopping blocks to fit; if applied correctly,
Concrete Manufacturers Association
the process can generate substantial cost
(CMA) website at no charge.
and quality benefits.
Isia Ortner, the architect who designed
“Preparing plans for proper modular
the CMA House, says that placing the
masonr y is time consuming bu t the
plans into CAD software means that they
extra ef for t is definitely wor thwhile.
can be easily modified and will therefore
As most subsidy housing developments
have much broader appeal.
involve the construction of +- 50 if not
“There is no such thing as a totally
hundreds of houses, the additional costs
standard house even at the subsidised
that detailed modular-masonry plans
h o u si n g l e v e l . E a c h d e v e l o p m e n t i s
entail, are rendered insignificant through
different, if only minimally, and CMA House
amortisation. Moreover, when the savings
plans can now be easily adapted to suit
that accrue from modular masonry are
specific developments.
realised, the preparation of detailed plans
“For example, CAD allows for easy
becomes even more compelling.
orientation and makes future extensions
“This poses the question as to why
much easier. It also facilitates mirror
all subsidy housing developments are
imaging as well as the adjustment of
not built using modular masonry? The
internal layouts,” comments Ortner.
sad truth is that most subsidy housing
Unlike most subsidy housing plans
developers are too focused on securing
which are basic, the CMA House plans are
architectural plans at the lowest
fully detailed, down to the last concrete
possible cost, and in so doing, miss out
block in fact. Central to the whole CMA
on the cost savings and improved quality
House concept is modular masonry which
aspects that detailed plans for modular
requires that each and every block and
masonry entail.”
CMA House plans designed with the 290 solid block.
4
NEWS
MAPEI APPOINTS NEW PERSONNEL Mapei South Africa has made four new appointments. L aur ence Gopane joined Mapei on 9 Januar y 2012 as senior technical consultant for its grinding-aids division. Gopane holds a BSc (Ed) degree and has over 13 years experience as a quality-
Johan Venter has been appointed as
merce degree in marketing, and has worked
a sales consultant f or Mapei’s Cape
in the construction chemicals industry for
Town region.
four years.
Previously employed as sales & technical
Martin Olivier joined Mapei on 1 May
consultant before taking the role of sales
2012 as a national specification consul-
manager, Ven ter has o v er 10 y ear s
tant. Martin has a national diploma in
experience in the construction industry.
building science and began his career
assurance chemist, cement and concrete
Tanya Duvenage joined Mapei on 24 April
in housing. Prior to joining Mapei
laboratory supervisor, production and
2012 as a senior technical consultant for
he worked on cellular-tower construc-
quality superintendent, and as a technical
its extensive building range.
tion as a senior pr oject planner and
Duvenhage holds a Bachelor of Com-
consultant.
Laurence Gopane
Johan Venter
Tanya Duvenage
quantity surveyor.
Martin Olivier
EASIER NAVIGATION ON REVAMPED TERRAFORCE WEBSITE Terraforce, a Cape Town-based precast concrete licensor, specialising in modular, hollow-core concrete blocks, has announced a redesigned website. Terraforce marketing manager, Karin Johns, says the new site provides a more cohesive web presence for its licensee network, and has improved the overall user experience for all other visitors to the site. “Considerable thought has gone into our Web presence and we are delighted with the new design. Besides easier navigation, the site provides our clients and prospective clients with a practical access point where they can find important in f orma tion on our pr ecast modular concrete blocks, quickly and easily. The site also includes a comprehensive Q&A section, a PDF downloads page for technical manuals, bill of quantities, recommended specifications and detailed submission sheets, and an easy subscription to a monthly newsletter,” says Johns.
Terraforce takes pride in sustainable and attractive retaining wall design.
Terraforce’s licensees can now also be contacted through several Web-based platforms, as each licensee has been allocated a separate page. These pages allow Web users to contact licensees via email and they provide Google maps of each Terraforce associated business. A completely new feature of the site is its social-media connectivity. “Visitors can share content or follow Terraforce on LinkedIn, Facebook and Twitter. This makes the site considerably more interactive and turns it into a hub of information on the retaining wall industry in general,” comments Johns. Johan van Wyk, MD of Cape Retaining Systems, a Terraforce block supplier added: “Many of our customers’ first contact with us is via the Terraforce website, as Terraforce is a household name in retaining walls. We are very excited as the new website will make it easier for potential clients to reach us. Social media, which is used increasingly by the IT generation, is a vital adjunct to those who want to share information, specifically in a dynamic
A sampler page of Terraforce’s website which can be accessed via www.terraforce.com.
environment such as the retaining-wall industry.”
CMA ADOPTS FRESH APPROACH ON AWARDS FOR EXCELLENCE Coinciding with its 40th anniversar y
Commenting further, Laing says that an
celebrations, the Concrete Manufacturers
awards entry book won’t be published this
Association (CMA) has announced that its
year. Instead all entries will be posted on
2012 Awards for Excellence competition will
the CMA’s website and on Facebook. As
be run on an entirely new basis.
in previous years a winners’ book will be
Unlike in the past when competition
published and distributed immediately after
categories were product-based, this year
the Awards which will be staged jointly
the emphasis is on the core values and
with the Association’s 40th anniversary
standards on which precast concrete
celebrations on November 3rd at the Indaba
products and applications are measured,
Hotel in Johannesburg.
and the new award categories reflect this. These are as follows:
“The event presents an outstanding opportunity for all professionals involved
• Aesthetics
in the manufacture and application of
• Sustainability
precast concrete to establish themselves
• Community involvement
as trendsetters in their specific disciplines
• Technical excellence
C and to gain national recognition for their
• Innovation
achievements,” concludes Laing.
• Vintage Besides the new categories, the number
M
The deadline for entry submission is Y
June 29th and judging by constructionCM
of awards has been halved from 36 to
related professionals will take place in
18. Moreover, the thee-tiered structure
MY August. Award entry forms together with
comprising regional awards and ceremonies,
the competition rules can be downloaded CY
national awards and five trophy awards has
from www.cma.org.za .
been dropped. It is being replaced by a single streamlined ceremony in which trophies are awarded to the overall winner of each category; in addition three commendation awards per category will be made. CMA director, Hamish Laing, says each category is open to entries from any construction project providing one or more precast concrete product manufactured by a CMA member has been used in its implementation. “Entries will be judged on the contribution that precast concrete elements make in one or more of the competition’s categories. In other words the same project could be entered for more than one competition category. For example, a township paving project could be entered into several if not all six categories.” Laing says the standards on which the award entries will be judged this year will be as high if not higher than they always were, and awards will only be made if the quality of entries meet competition criteria. In instances where standards are not sufficiently high, awards will be withheld,” says Laing.
CMY
K
8
NEWS
CONCRETE TECHNOLOGISTS NEEDED URGENTLY The biggest threat to the economic growth
Technology every two years under the
concrete, mining and also the cement,
of South Africa is the shortage of technical
auspices of the Institute of Concrete
aggregate, admixture, and ready-mixed
sk ills in engineering and technology,
Technology (ICT) in the UK.
concrete industries. Successful candi-
according to Bryan Perrie, managing
Delegates are drawn from qualified
dates will qualify for free membership of
dir ec tor o f the C emen t & C oncr e te
civil engineers, cement chemists, concrete
the Concrete Society of Southern Africa
Institute (C&CI).
technologists and technicians involved
while studying. The Society has officially
in the building, construction, precast
endorsed the course.
Speaking at a breakfast function in Midrand to mark the start of the C&CI School of Concrete Technology’s 2012 Advanced Concrete Technology ( AC T ) training course, Perrie said the shortage of qualified concrete technologists was a major component of the shortage of materials engineers in this country. “The ACT course will, this year, expose delegates to a wide range of concrete disciplines and insights that could provide a competitive advantage to both delegates and their companies,” Perrie stated. The globally-recognised ACT course is presented by the School of Concrete
The 21 delegates for the C&CI 2012 ACT class pictured with SCT lecturer, John Roxburgh (back row, extreme left).
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www.cma.org.za
For more information call our toll-free line on 0800 023 470 or visit www.ppc.co.za
amount of regular 32,5 N general-purpose cement. Imagine how much further your vision could go with 15% extra.
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TJDR 51988
Dynamon NRG & Dynamon SP Solutions specially designed for the precast concrete industry
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To solve specific problems encountered in the precast concrete industry and to strongly contribute to the development of this sector, Mapei has developed the DYNAMON NRG and DYNAMON SP product ranges. These products are specifically intended for this type of application and are especially suitable for manufacturing self compacting concrete.
Facilities Management Exhibition Visit us at the
29 - 30 May 2012
stand B3
Sandton City Convention Centre
www.mapei.co.za
Contact us: +27 11 552 8476 or info@mapei.co.za ADHESIVES • SEALANTS • CHEMICAL PRODUCTS FOR BUILDING PRECAST VOLUME 6 • ISSUE 1 • 2012
NEWS
11
PAVING STANDARD AMENDED The new standard for the manufacture
majority of manufacturers which weren’t
of concrete block pavers (CBP) SANS
able to comply with the new standard
1058:2010 was of ficially amended by
consistently, even though a few had been
the South African Bureau of Standards
able to do so.
(SABS) on February 8, 2012 and is now known as SANS 1058:2012. The upshot for CBP manufacturers is that Edition 2.0, which was f ir st
CMA director, Hamish L aing, says although the per formance criteria of Edition 2.1 are lower than Edition 2.0, they are only so marginally.
announc e d in Mar ch 2010 as S A NS
“Edition 2.1 of SANS 1058:2012 still
1058:2010 and then officially introduced
sets a higher quality benchmark and is
in September 2011, has been replaced by
considerably more comprehensive than
Edition 2.1 as SANS 1058:2012.
SANS 1058:2006,” says Laing.
The requirements for two of the three
In addition to the amendments, the
performance measurement techniques in
standard’s two strength ratings were
the new standard, tensile splitting and
renamed for greater clarity. These are
abrasion testing, have been lowered, and
Class 30/2.0, officially rated at 2.0.MPa
the third, a water absorption test, has
(tensile strength), and Class 40/2.6, rated
been placed on a voluntary footing.
at 2.6MPa (tensile strength).
BIRKENMAYER APPOINTMENT
Initiated by the Concrete Manufacturers
A n o f f i cial t e chni c al n o t e o n th e
Mr. Anthony Makgale has been appointed
Association (CM A ), the amendments
amendment is a v ailable on the CM A
as sales engineer at Birkenmayer in
wer e in tr o duc e d t o ac c ommo da t e a
website and page 14 of this issue.
Johannesburg.
12
ARTICLE
EXTENSIVE RETAINING-WALL PROJECT FOR NEW SHOPPING CENTRE One of the largest retaining wall projects ever undertaken in South Africa is currently under construction at Cradlestone Mall, a new shopping centre in Muldersdrift, which is being constructed for the Sasol Pension Fund and Retail Africa by Aveng Grinaker-LTA. Designed as gravity retaining walls by
built, including a perimeter wall around
and temporary 70º slopes have and are
the entire site and several walls within
being created in the dolerite sections prior
the site itself.
to erecting retaining walls. Excavated
Sloping ground has necessitated ter-
dolerite, which conforms to a G6 material
racing with cut-to-fill earthworks and is the
standar d, is being used f or the bulk
main reason why retaining walls are playing
earthworks fill.
such an important role in this project.
Before Diesel Power moved on site,
The Cradlestone Mall walls are being
geotechnical testing involving pits and
built by CMA contractor member, Friction
augered holes indicated no observable
Retaining Structures, working as a sub-
seepage. Despite this it was recom-
contractor for earthworks contractor,
mended that the retaining walls and the
Diesel Power.
fill behind them be rendered waterproof
Silvio Ferraris, CEO of concrete retaining
Site material consists predominantly
blo ck ( C RB ) m anu f a c tur er an d C M A
of residual dolerites and dolerites as
Drainage is being installed above the
member, ReMaCon Products, the walls are
well as some potentially collapsing soils.
finished levels directly against the cut
being built on a site situated between the
However, the latter are not expected to
faces. It consists of perforated 110mm
N14 highway and Hendrik Potgieter Drive.
be problematic. The dolerite constitutes
Just under 2 000m of walls are being
an acceptably stable founding material
PRECAST VOLUME 6 • ISSUE 1 • 2012
with good drainage.
Completed retaining wall sections at Cradlestone Mall.
ARTICLE
13
piping which is covered with 19mm stone.
sustained loading and it has a 27kN long-
contractor is essential to any successful
Both the stone and the piping are being
term design strength rated at 5% strain.
CRB wall project.
wrapped with A2 bidim to prevent soil
This means that in the unlikely event
“This prevents problems from
fines from clogging the stone. Bidim is
of any soil movement, the fabric will be
developing and solving those that do
also being laid against the cut faces to
sufficiently resilient to ensure that the
promptly and inexpensively. This aspect
prevent the possibility of any sub-surface
stretch factor won’t be greater than 5%
is working extremely well at Cradlestone
water from percolating through the soils
at maximum permissible strain.”
Mall,” concludes Ferraris.
and destabilising the walls. Any seepage
Commenting further, Ferraris said that
will be transmitted through geofabric into
in opting for CRB walls rather than vertical
the drains and this will prevent phreatic
in situ walls at Cradlestone Mall, at least
pressure from developing behind the walls.
50% was saved on costs and an additional
Varying in height between 1m and
60% on time.
10m, the walls are being built either as
“A v e r t i c a l w a l l r e q u i r e s a h u g e
cut-face or as bulk reinforced structures,
f oundation with steel r einf or cement
the latter using fill material and geofabric
and steel starter bars. It also involves
reinforcement supplied by Kaytech. All the
shuttering on both sides of the wall,
walls are being constructed at an angle
the pouring of wet concrete, waiting for
of 65º using 8 000m² of Terraforce L11
the concrete to set and stripping the
blocks, manufactured under license by
shutters. Then one still has to compact
ReMaCon. The same blocks are being used
the ma ter ial f ill behind the wall. B y
for the base courses, but in instances
contrast CRB walls are simpler and quicker
where the walls are higher than seven
to erect, and more attractive, especially
metres, the blocks are supplied in greater
when filled with plants.
strength ratings.
Risidual dolerties and dolerites at Cradlestone Mall are cut and excavated prior to reinforcing with concrete block retaining walls
“However, one has to weigh up the
Ferraris comments that flatter walls
additional cost of vertical walls versus
are less imposing and more attractive
the space they save. When space is at a
and that walls steeper than 70º require
premium and the cost of land extremely
considerably more engineering.
high, the additional cost of vertial walls
He says that geofabric reinforcement is
P
can sometimes be justified.”
being used on walls six metres and higher.
Ferraris advises that communication
“Minimum geofabric depths begin at
and cooperation between the earthworks
three metres and vertical spacing varies
contractor and the retaining-wall block
Partially completed earth-works and retaining wall sections seen here at Cradlestone Mall.
from 450mm to 900mm, depending on wall heights. Up to 15 layers are being used on the highest walls. “Because the terraces are soil-filled, geofabric is installed to intersect soil planes and the designer must ensure that the combined force of the geofabric is greater than that exerted by the soil. The type and depth of fabric is determined by the wall angles. SANS 207 states that if the angle is less than 70º, geofabric with a 5% strain can be used. In such instances the geofabric is allowed to stretch by 5%, which at Cradlestone Mall means that the angles of the walls can steepen from 65º to 68,2º. However, this is unlikely to happen due to the good quality of on-site fill material and the shear interaction between the soil and geofabric. “The geofabric specified for Cradlestone Mall is Kaytape woven polypropylene S270 with a short-term rating of 50kN. It is designed to stretch and creep under
One of several retaining walls which follow the contours on the cut-to-fill earthworks project at Cradlestone Mall.
PRECAST VOLUME 6 • ISSUE 1 • 2012
TECHNICAL NOTES
NEW CONCRETE BLOCK PAVING STANDARD AMENDED The official standard for the manufacture of concrete block pavers (CBP) SANS 1058:2012 has been amended.
COMPARISON OF OLD AND NEW SPECIFICATIONS
With effect from February 2012, Edition 2.1 replaced Edition 2.0, which was first announced in March 2010 and became official in September 2011. This was the 18-month window period for manufacturers to alter their mix designs and production processes in compliance with the new standard. Initiated by the Concrete Manufacturers Association (CMA ), the amendment was made to accommodate a majority of manufacturers which weren’t able to comply with the new standard consistently, even though a few were able to do so. The performance criteria of Edition 2.1 ar e ther ef or e lower, albeit only marginally. Edition 2.1 of SANS 1058:2012 still sets a higher quality benchmark and is considerably more comprehensive than the standard it replaces. In addition to the amendments, the standard’s two strength ratings were renamed for greater clarity.
However, to help the industry better understand the new per formance measurements, SANS1058:2012 still refers to the old compression standard, even though it does not form part of the new standard.
Unlike the old standard, SANS1058-2006, which relied on a single, compression based measurement, SANS1058:2012 includes two new performance measurement techniques: tensile splitting and abrasion testing.
The CMA made a conscious decision to increase the performance requirement of quality concrete block pavers in drafting the new standards in collaboration with SABS and to this end, two upgraded strength ratings were added.
Class 30/2.0, officially rated at 2.0MPa (t ensile s tr eng th ), is indic a ti v e o f a c o m p r e s si v e s t r e n g t h r a t in g o f around 30MPa, and Class 40/2.6, rated at 2.6MPa (tensile strength), approximates a compressive strength rating of about 40MPa. Unfortunately there is not a direct correlation between the tensile and compression strength of a concrete block paver. This relationship varies depending on aggregate type, shape and grading and the amount of vibration available during manufacture. For specification purposes, Class 30/2.0 replaces the old class 25 of SANS10582006, which was based on a compressive strength rating of 25MPa, and Class 40/2.6 replaces the old Class 35 based on a compressive strength rating of 35MPa.
A set of paving blocks after a run on the abrasion testing machine.
Tensile splitting is a far more appropriate performance measure than compressive testing because it measures resistance to cracking and break-ups as opposed to resistance to crushing. Research has shown that paving blocks are hardly ever crushed under load whereas cracking and break-up as well as abrasion are the main causes of paving failure. The tensile-split test involves applying line loads to the top and bottom of the blocks using two steel bars, each with a diameter of 150mm. Plywood strips are inserted between the bars and the blocks to ensure an even load distribution. More importantly, the test takes the thickness of the block into account whereas thickness was not a factor in compression testing. It is known that paving blocks with good strength ratings do not necessarily provide good abrasion resistance, which is why a surface-wear test has been included in the new standard. Abrasion is specific to the quality, density, shape and particle distribution of the aggregates used in the topping layer
and the percentage binder. For example, a paving block with a high strength rating can have low abrasion resistance. Conversely, a block with a low strength r ating can have excellent sur f acewear properties. Most South African paving producers manufacture pavers with two layers. The bottom and thicker sections provide the required strength. The top layers, w hich ar e a t le ast as str ong, ar e coloured with pigments for enhanced aesthetic appeal. Now that the new standard measures abrasion r esistance, these topping layers are being designed with excellent surface-wear properties. Even lowergrade blocks with a good topping layer can of fer high abrasion resistance, providing the topping layers do more than offer colour variation. It is important to note that pedestrian traffic is highly abrasive, more so than most other forms of traffic. As part of its research for the new standard, the CMA investigated all forms
Abrasion testing machine.
of abrasion resistance, testing various systems around the world. In the end, it opted for the Australian/New Zealand model, which proved to be suited to in-situ performance conditions. The amendments to SANS1058:2012 restrict the average mass loss per block to 15g after being pounded by 600 16g ball bearings for 60 minutes in a rotating steel box. A water absorption test had been included in the original SANS1058:2010 because CBP with low absorption rates tend to offer better durability but the test has been dropped in the amended standard. The denser a block the lower its water absorption rate and a block with good density will almost invariably pass the tensile-splitting test. The absorption test was first introduced in Europe to prevent blocks from shattering when frozen. Although the requirement has been left out of the amended SANS1058:2012, it remains an informative and voluntary part of the standard. It is strongly recommended that both private and public specifiers adopt the revised standard as soon as possible and that block users check compliance with the new standard prior to ordering.
A tensile spilt test underway.
FOR MORE INFORMATION, CONTACT THE CONCRETE MANUFACTURERS ASSOCIATION (CMA) Block D, Lone Creek, Waterfall Office Park, Bekker Road, Midrand • PO Box 168 Halfway House 1685 Tel: +27 11 805 6742 • Fax: +27 86 524 9216 • E-mail: main.cma@gmail.com • Website: www.cma.org.za
ARTICLE
Recently laid 650mm concrete piping prior to being connected by an in situ built manhole.
Sections of 650mm concrete pipe are aligned with laser beams prior to joining and sealing.
17
Two 1 650mm stormwater concrete pipes prior to being connected by an in situ-constructed drop box.
CONCRETE PIPING SPECIFIED FOR INFRASTRUCTURE PROJECT Just under 5 000m of precast concrete stormwater piping is what it will take to drain Waterfall City, currently under construction and earmarked to become Midrand’s new central business district. The concrete pipes were specified by the Johannesburg Roads Agency ( JRA) for what is seen as one of Gauteng’s largest infrastructure projects to date. Driven by Atterbury Property Developers, the initial development will comprise 800 000m² of letable space when completed in 2018.
supplied by two Concrete Manufacturers Association (CMA) members, Rocla and Southern Pipeline Contractors. Infrastructural work began in 2009 when aerial sur veys established land gradients. Labucon moved on site in 2011 where it will remain until the completion of all infrastructure work in August 2013. This includes the construction of some six kilometres of roads and the laying of
Spanning 125 hectares, the site forms
A section of 650mm concrete piping is covered with soil after laying and joining. A layer of bidem sheeting which is installed to prevent excess water from penetrating beneath the road surface can be clearly seen on the right.
4 985m of concrete stormwater piping.
part of a 565 hectare estate (formerly
The stormwater piping project began in
owned by the Mia family) bordered by
November 2011 and will be completed in
Allandale Road , the Johannesburg/Pretoria
November 2012. The pipes, in diameters
highway, Woodmead and a mushroom farm.
from 450mm to 1 950mm, will drain
Infrastructural planning and project
the site and discharge into three water
management is being undertaken by C-Plan
channels which will ultimately feed into the
Consulting Engineers. Earthworks, road
Jukskei River to the south.
infrastructure and the installation of
Trench depths vary between 1.5m and
stormwater, fresh water, and sewerage
5,5m, and with natural gradients as high
piping falls to Labucon Resources, while
as 1 in 20 in some places, 17 drop boxes
the concrete stormwater pipes are being
are being built at T junctions and at bends
PRECAST VOLUME 6 • ISSUE 1 • 2012
18
ARTICLE
Trenching and stormwater pipe laying at Waterfall City.
One of the infrastructure plans for Waterfall City.
to reduce water velocities. In addition
providing additional founding stability for
manholes are being constructed in all
the pipes and blasting is breaking up the
other places where there is a change of
rock which is then crushed and used as
pipe direction.
dump material for a road-building project
A c c o r din g K C O o ij k a a s o f C - P l a n
Sias Swart, contracts manager, says
being built to Johannesburg Roads Agency
the stone bedding pr events any soil
( JR A ) standar ds f or which concr ete
movement from exerting excessive stress
stormwater piping is mandatory.
on the pipe joints.
“Precast concrete is the best material
“We are also using a laser-beam system
for stormwater drainage, which is why
to ensure that the pipes are properly
it forms part of the JRA road-building
aligned,” says Swart.
specifications,” says Ooijkaas.
Two 1 950mm pipe sections prior to being connected by an in situ-built manhole.
on an adjacent site.
Consulting Engineers, all the roads are
The pipes are connected with ogee
Besides fairly steep gradients, other
joints. These are rendered water-proof
engineering challenges included outcrops of
through the application of a water-based
rock and a high-water table. Stone bedding
damp seal to the joints and on 20mm of
comprising 19mm imported aggregate is
piping surface on either side of the joints. This area is then covered with A4 bidem sheeting and a second coating of damp seal. Bidem sheeting is also being installed on the land embankments which rise above the pipes so that excess ground water is prevented from penetrating beneath the road surface material, in this instance bitumen. Instead, water will be trapped by the bidem and channelled into perforated 160mm PVC pipes, which run parallel to the stormwater pipes, before discharging their contents into the manholes. To prevent them from being clogged with soil, the PVC pipes are covered with 19mm stone and wrapped in bidem. Wingwalls are being installed where the pipes discharge into the water channels to prevent soil ereosion. However, the
An aerial view of the Waterfall City site.
PRECAST VOLUME 6 • ISSUE 1 • 2012
Waterfall City project is setting a prec-
ARTICLE
19
edent in that two of its wingwall outlets
CM A dir ector, Hamish L aing says
are not being constructed on site. Rather
that besides its durability and long life-
when working in trenches. “There is a great deal of knowledge on
they have been factory-built in precast
span, concrete piping is far less depend-
concrete and its related performance, as
concrete by Rocla.
ent on embedment material than a flexible
opposed to new piping materials on which
Recently introduced to the local market
pipe. Because concrete piping is rigid,
field knowledge is scant. If you want value
by Rocla, and JRA approved, precast
contractors don’t incur the same sort
for your money, and aim to get it right
wingwalls offer several advantages such
of difficulties as they do with the proper
first time, concrete is the route to go.
as very much quicker installation, a lower
installation of flexible pipe products. These
We can’t afford to have reworks in South
material requirement, no formwork and
difficulties become even more pronounced
Africa,” concludes Laing.
no waste. They are installed by crane, and depending on gr ound conditions, take between 15 minutes and an hour to install. By contrast, in situ wingwalls take a minimum of two days to construct and seven days to cure and can also be adversely affected by rain shortly after construction. Craig Waterson, sales and marketing director of Rocla, says that in stormwater applications, wingwalls direct the water into a flow path that will result in the least amount of turbulence, thereby optimising the hydraulic capacity of the conduit. “P r e c a s t w i n g w a l l s c o m e w i t h a separate precast concrete toe which keys the entire unit to the ground and prevents any movement. The toe also reduces the risk of soil scouring below or to the side of the toe,” says Waterson.
A five-ton precast concrete wingwall and concrete toe prior to installation at Waterfall City.
P
20
ARTICLE
Precast wave wall being unloaded and ready to be placed.
Lifting the concrete ‘mattresses’.
UK FLOOD ALLEVIATION SCHEME OPTS FOR PRECAST CONCRETE ELEMENTS The north-east coastal town of Redcar lies on a naturally eroding coastline and has in recent years suffered from significant breaches in its sea wall. Flood modelling estimates show that 978 homes and 209 business premises are at risk of sea flooding. Without improvements to the sea defences a further 184 residential and 98 commercial properties would be at risk within the next 100 years. Brian Farrington of Birse Coastal reports.
the natural ‘Scar Rocks’ formation, which
Birse Coastal worked closely with the
of coast protection in order to meet the
Environment Agency, Redcar and Cleveland
required standard of protection against
Borough Council, designers, architects
flooding.
This article first was published in February by Concrete, a UK-based journal which covers various aspects of concrete usage.
also provides an important feeding ground for visiting birds. As a result, the finished works and also the method and timing of the work required close consultation and agreement with Natural England. The scheme is split into two distinct sections that require different methods
and suppliers during an extensive Early T he Redcar Flood Alleviation Scheme
Contractor Involvement (ECI) phase. The
Specially designed
involves protecting a 2.7km stretch of
ECI process is a key part of developing
The 1.5km esplanade will be protected by a
coastline from Coatham Boating Lake in the
high-quality sustainable solutions that can
specially designed precast stepped concrete
west, along the esplanade in the centre of
be constructed safely and with minimum
revetment with a precast reinforced
town and The Stray to the east.
disruption to the local community.
concrete curved wave return wall on the
For over three years prior to the
The site also sits within a Site of Special
scheme reaching construction stage
Scientific Interest (SSSI) area containing
PRECAST VOLUME 6 • ISSUE 1 • 2012
top and a steel pile or concrete beam at the toe, which provides scour protection.
ARTICLE
21
The precast units are being manufactured by Macrete at its facility in Ireland and shipped by road via Heysham. As the new sea defence is also an integral part of the regeneration of the promenade, not only was a high-quality finish required but also the curved wave walls use a buffcoloured concrete to complement the finishes on the promenade and match the natural beach colour. Re-landscaping the seafront
significant benefits to coastal schemes
As well as replacing the sea defence in this
through the use of its modern fleet of
section, Birse Coastal is working together
cranes and its expert operators.
with Redcar and Cleveland Borough Council to re-landscape the seafront, creating an
Technological development
enhanced visitor experience and amenity
One particular technological development
area for residents and tourists. This will
came through discussion on a previous
include leisure and entertainment spaces,
scheme with Blackpool Tower operators
water-play areas and quiet areas where
about materials and maintenance systems
the atmosphere and natural wildlife can be
they use in the tower lifts. As a result,
enjoyed. It also incorporates high-quality
BPH Equipment has increased its use
coloured precast concrete steps laid out to
of multi-core compacted wire rope on
give the impression of a long ‘wave’ effect.
cranes instead of the three-core wire
Placing wave wall and completed section in place.
T h e f ir s t a r e a o f t h e si t e t o b e
rope used traditionally. This, together
problem for cranes working for lengthy
constructed on the scheme invol ved
with a forensic inspection regime and the
periods in coastal environments.
placing some of the largest precast units
use of a high-specification rope lubricant,
The 1.2km Stray requires a slightly
ever installed by Birse Coastal. These were
has signif icantly r educed the risk of
reduced standard of protection due to
the 6m-high walls that surround the old
corrosion and associated maintenance
the natural sand dune system that forms
nightclub site, with the largest precast
costs, which had traditionally been a
a barrier between the roadside housing
units weighing in at an impressive 28 tons.
and the sea.
Detailed planning and sequencing of precast
This area will be protected by repairing
unit manufacture, delivery and storage with
the existing groynes, overlaying the current
supplier Macrete is required to ensure
sloping defence with a precast concrete
construction progresses smoothly. The
mattress, constructing a short section of
close working relationship with sister
flood defence wall beside the paddling pool
company BPH Equipment has provided
and creating a new promenade. Programme restraints T h e r e a r e signi f i c an t c h all e ng e s t o overcome while constructing the scheme, including programme constraints that limit both working areas and the times of year that par ticular areas can be accessed. For example, the town centre area needs to be kept free for tourists to use during the summer season and working hours are restricted at the west end of the scheme either side of high tide so as not to disturb visiting birds, which congregate in the boating pool area when the tide is in. The £21 million project started in January 2011 and should be complete and ready for residents and
Mattresses and revetments in place
visitors to enjoy in early 2013.
P
PRECAST VOLUME 6 • ISSUE 1 • 2012
22
APPLICATIONS
CONCRETE BLOCK RETAINING WALLS PROTECT BURGERSFORT WAREHOUSE
Small said that during construction, high-tenacity, polyester-coated woven reinforcing grids were installed at every third block and that the tieback length of the grid was equivalent to 80% of wall heights.
A 146m concrete block retaining (CRB)
was undertaken to create space for the
Moreover, soil compaction levels one
wall which reaches a maximum height of
geosynthetic reinforcement of the walls
metre in from the external wall face were
8,5m, has been built for Amidad Trading
and the excavated soil was stockpiled for
carefully monitored during construction
using Aveng Manufacturing Infraset’s
re-use as backfill material. There were also
to ensure that the blocks wouldn’t be
Ridgeblok® at new warehouse premises
outcrops of rock in some sections of the
pushed forward during the lifespan of the
in Burgersfort, Mpumalanga.
embankment and compressors were used
walls, as this would steepen the angle of
to break it up,” said Small.
the wall faces.
A second wall, three-metres high and 55m long, was built on the same site with
Actual construction began by laying
Small advises that a good drainage
Aveng Manufacturing Infraset’s Terrace
base blocks at 85º on top of the foundations
system is essential to the proper
Blok® TB300 and TB490 retaining blocks.
which were 100% level. This created a level
functioning of a retaining wall.
Designed by TMV Consulting and built by
base and the desired starting point five
Engineered Interlock Solutions, the walls
degrees off the vertical.
“Drainage of the Burgersfort walls was achieved through the installation
were erected to protect embankments
of perforated pipes covered with 19mm
adjacent to the warehouse.
s t o n e an d w r ap p e d w i th n o n -w o v e n
Brennan Small, Aveng Manufacturing
polyester sheeting. A needle-punched
In f r ase t: L andsc ape Pr oduc ts sales
geotextile fabric was laid against the back-
manager, comments that the walls were
face and drainage outlets were installed
erected at steep 85º angles in order to
at three-metre intervals. Furthermore,
free up as much space as possible for the
250 wick drains were installed against the
construction of the warehouse. “The site is situated on a fairly steep slope and a level platform was created by excavating into the slope. “Further cutting into the embankment
back-face to collect any sub-surface water Reaching 8,5m at its highest point and stabilising a 146m embankment, this concrete block retaining (CRB) wall was built for Amidad Trading using Aveng Manufacturing Infraset’s Ridgeblok® at new warehouse premises in Burgersfort, Mpumalanga.
behind the reinforced backfilled sections.” Small concluded by saying that the pr oject complied with all SA NS 207 requirements.
PPC CEMENT USED FOR DE HOOP DAM Southern Africa’s largest cement supplier,
been used, the latter having enhanced
PPC Cement, is supplying cement for the
cement yields by 15%.
construction of the De Hoop Dam in Lim-
“Owing to an overwhelmingly positive
popo. PPC will continue to do so over the
r esponse on OP C 52.5N cement we
duration of the four-year project which is be-
proposed its use for the De Hoop Dam to
ing run by the Department of Water Affairs.
the Department of Water Affairs and it has
Situated on the Steelpoort River, the
been used on the project since July 2011.
dam wall will be close on 85 metres high
“The enhanced OPC cement has been
and contain around 1.125 million cubic
formulated to enable end-users to produce
metres of concrete (700 000m³ when
cost-e f f ec ti ve concr ete and r elated
compacted) on completion in March 2013.
products, and through stringent quality
PPC had supplied 77 517 tons of cement
con tr ol me asur es, the new pr oduc t
at the time of writing.
ensures consistent performance.”
Marius Joubert, PPC area sales man-
Johan van Niekerk, Depar tment of
ager, says the project demonstrates PPC’s
Water Affairs site manager comments:
flexibility in meeting stringent deadlines
“We are extremely happy with the enhanced
and an ability to produce vast quantities
OPC product as it has been one of the
of cement.
contributing factors to the success of the
“Cement for the dam was supplied from
project. We have also received exceptional
our Dwaalboom factory in Limpopo and our
support from PPC’s technical specialists.”
Hercules plant in Pretoria. Both OPC 42.5N and the enhanced OPC 52.5N cement has
PRECAST VOLUME 6 • ISSUE 1 • 2012
The new De Hoop dam wall which is being built with PPC cement.
SIKA SUPPLIES ADMIXTURES FOR EARTH-CORE DAM Sika’s SikaPlast-V210 concrete admixture has been specified by MBB Consulting Engineers for the construction of the first phase of Ludeke Dam, in Mbizana, Eastern Cape. A multi-purpose water reducer and super plasticizer incorporating Sika’s ‘ViscoCrete’ polycarboxylate polymer technology, SikaPlast-V210 was used to construct the intake towers and the spillways. Selected for its versatility, good slump retention and optimised mix design, the product contains no formaldehyde, calcium chloride or any other chlorides, and as such will not initiate or promote the corrosion of steel in the concrete. Due to substantial steel reinforcement, 580m³ of concrete had to be poured continuously into the base of the intake towers, a process which took 27 hours, far longer than any standard concrete pour. The dam, pump station and rising main form the rawwater components of the Mbizana Bulk Water Supply Scheme initiated by Umgeni Water. The wall is 240m long and almost 40m high and the dam’s maximum storage capacity is in excess of 14.5 million cubic metres, providing much needed supply to 266 000 people in surrounding communities. Budgeted to cost R218 million, this is one of a very few earth-core dams in the country. The dam wall comprises a clay-cored rock-fill embankment with a concrete-lined side-channel spillway. The pump station will supply water through a 13.9km steel pipeline to an existing water treatment works. The estimated earthworks volume is approximately 600 000m3. An unseasonably high winter rainfall has posed additional challenges for the contractor, Rumdel Cape, which had to waste valuable construction time draining excess water. The project is scheduled for completion in September this year and Sika will be supplying many more litres of SikaPlast V210 as well as several of its other high performance products.
The Ludeke Dam wall under construction.
24
APPLICATIONS
CONCRETE BLOCK PAVERS – THE PEOPLE’S CHOICE IN HEIDELBERG The use of concrete block paving (CBP) as a road-paving material in townships is widespread, certainly much more so than most realise. The Concrete Manufacturers Associa-
One of the CBP roads laid by community members in Ratanda, a township in Heidelberg (Lesedi).
tion (CMA) has done some research into CBP township sites scattered across
aspects were other considerations which
he was initially responsible for designing
the country in diverse locations such as
influenced our CBP decision and our tender
the roads himself, but that as from 1996,
Rustenburg, George, Stilfontein, and Dur-
process ensures that all concrete paving
the volume of work meant that external
ban. Long-term and ongoing, most of them
blocks and concrete kerbing materials are
consultants were required, and since then
were initiated after 1994, and besides pro-
SABS approved.”
consulting engineers have been appointed
viding low-maintenance and highly durable
An interesting aspect of Heildeberg’s
road surfaces, are creating much needed
CBP initiative is that in addition to the
Much of the recent civil work has been
work for and the transfer of skills to local
township projects some suburban roads
handled by Century Civils, a specialist
communities.
have been surfaced with CBP as well. These
earthworks company, whereas local sub-
include upmarket Jordaan Park and middle-
contractors employing local community
income Heidelberg Ext 9.
members have laid the paving and installed
One initiative about which very little had been heard until recently is situated in
each year.
Heidelberg (Lesedi), Gauteng, where some
“Besides features such as exceptional
the kerbing. Training is given to new
90km of township roads have been paved
durability and labour intensity, CBP’s
recruits and refresher training courses
and kerbed over the past 17 years.
superior aesthetics is what swayed our
are also given by various accredited service
For example, all the roads in Ratanda
decision for suburban use,” said Aufmkolk.
providers when required.
Ext 7 and Heidelberg Ext 23 have been
Commenting further Aufmkolk said that
Most of the roads are five metres wide,
surfaced with CBP, and these projects
although some span 7.4m and wider. The
are due to be completed in 2012/13. A
material composition of most of the roads
more recent project, Jameson Park, was
comprise: a compacted sub-grade (in situ
completed in January. Currently, CBP road
material); a sub-base of stabilised gravel;
work is taking place at Impumelelo and
and the paving blocks.
paving will begin in other townships as and
“Collapsing soils and water presented
when funds become available.
problems on some of the roads and in these
Peter Aufmkolk, paving project manager
instances soil up to a depth of two metres
for the Lesedi Local Municipality, says the
was excavated. We replaced the soil with
main motivation behind the CBP project was to create jobs for the town’s local
A road surfaced with concrete block paving in Ratanda Ext 8, a Heidelberg (Lesedi) township.
communities.
stone and layers of gravel 150mm deep,” said Aufmkolk. CMA director, Hamish Laing, says that
“Municipalities are under tremendous
one of the advantages of CBP, as opposed
pressure to create work and the labour-
to asphalt road surfaces, is that the paving
intensive nature of CBP not only addresses
block forms part of the structural layer.
this challenge but fits in with Government’s
This means that the sub-base layer doesn’t
E x p a n d e d P u b li c Wo r k s P r o g r amm e
have to be as thick.
(EPWP). There is massive unemployment
Aufmkolk says Heidelberg’s CBP project
in this area and although paving projects
will continue until close on 100% of its
create work for a limited number of people
township roads are paved with CBP.
over short periods, it is highly valued by community members. “The low-maintenance and high-durability
PRECAST VOLUME 6 • ISSUE 1 • 2012
“It’s a win-win situation for the comOne of several CBP roads in Jordaan Park, an upmarket suburb in Heidelberg (Lesedi).
munity and the Lesedi Local Municipality,’ concludes Aufmkolk.
CONCRETE SOLUTIONS FOR UNDERGROUND CONSTRUCTION PROJECTS Underground mining operations in South Africa can undertake numerous construction projects swiftly and cost-effectively, by making use of a range of concrete-placer pumps manufactured locally by SEM Concrete Pumps, which forms part of the PMSA group of companies. SEM general manager, Sarika Lutchman, points out that SEM specialises in the manufacture of concrete-placer pumps that are specifically designed for use in underground mining applications. “SEM concrete placer-pumps are air-operated, making them ideal for underground mining applications.” Lutchman notes that SEM concrete-placer pumps are used in underground mines for several applications, which include shaftsinking and lining, the construction of ore passes, dam walls or settlers, foundations and support structures. SEM concrete placer-pumps include the wheel-guided SEM 100 with a 100l per-batch capacity, a maximum output of 6m³ per hour and a maximum pumping distance of 100m horizontal or 18m vertical. “With a headspace of 140cm and a weight of just 235kg, the SEM 100 is easily transportable, even in the most restricted areas. The SEM 100’s impressive production output, combined with its compactness and ease-of-use, has proven particularly popular among the largest names in the mining industry,” notes Lutchman. The second model in the SEM concrete placer pump range is the SEM 250, which has a 250 litre capacity-per-batch, a maximum output of 19m³ per hour and a maximum pumping distance of 150m horizontal or 18m vertical. “The SEM 250 is generally used where relatively large outputs are required, but where headroom or access is restricted underground. The SEM 250 is supplied either on a fixed stand or on a two-wheel site trailer,” Lutchman advises. For further information contact Quintin Booysen on 086 100 7672 or on quintin@panmixers.co.za. Web: www.pmsa.com
Underground concrete pumping.
26
APPLICATIONS
NEW SUPER-SEALANT FROM MAPEI
Mapeflex Blackfill is not recommended for use in areas that carry pedestrian or vehicle traffic, nor for compressive, tensile, continuous or snap-shear stresses.
Mapei, an industry leader in construction
construction features on flat and
and concrete technology, has introduced
sloping roofs, including flues,
Mapef lex Black f ill, a one-component,
skylights, aerials and guttering
flexible, bituminous sealant, to the local
• Collaring around pipe-work
solid and free of dust, loose particles, oil,
building and construction market.
• Filling joints, cracks and gaps of
grease, wax, and old paintwork.
This innovative sealant is manufactured
any size.
For the best results with Mapeflex Blackfill, surfaces should preferably be dry,
“If the product is applied to damp or wet
from polymers with a sof t solvent
The product is not prone to leaching
substrates, any stagnant water should be
consistency and is ideal for quick sealing
and does not dissolve in water, allowing
removed and the product must be applied
and repair applications for most surfaces.
immediate exposure to rain after application
by pressing it sufficiently. Moreover it
“Due to its soft consistency, Mapeflex
and does not run or drip, even when applied
should not be used in temperatures below
in wide sloping or vertical joints.
5°C,” says Nieuwoudt.
Blackfill forms a plastic mass that is easily extruded and shaped. The product bonds to most substrates, such as cementitious material, wood, bricks, metals and a number of plastics,” says Paul Nieuwoudt, product manager for Building Systems, Mapei South Africa. Applications of Mapeflex Blackfill include: • Localising seals on old bitumen
membranes without the laborious task
of getting specialised heating
equipment and gas on site
• Overlapping and filleting-in bitumen membranes • Sealing air vents • Immediately sealing gaps between
Mapei’s innovative bitumen sealant, Mapeflex Blackfill.
APPLICATIONS
27
‘FUNDAMENTALS OF CONCRETE’ UPDATED The updated, second edition of the Cement
architecture and other practitioners who
fresh and hardened concrete, mix design
& Concrete Institute’s acclaimed reference
require a working knowledge of the subject.
and proportioning, quality control and sta-
book, Fundamentals of Concrete, is now
The new 308-page edition - which con-
tistics, formwork, reinforcement, manufac-
tains many full-colour illustrations - has
ture and handling of concrete, sand-cement
First published in 1998, the book is
been updated and extensively expanded,
mixes, appearance of concrete and special
intended for students of engineering,
and now covers sustainability, concrete’s
concretes. For more information and or-
building management, quantity surveying,
constituent materials, the properties of
ders, contact publications@cnci.org.za.
available from the Institute.
FOXING EFFLORESCENCE Roof-tile manufacturer Coverland, the South
CHRYSO®Pareflo 20 reduces efflores-
African brand of the global Monier Roofing
cence and does not affect the strength of
corporation, is using CHRYSO®Pareflo 20,
the concrete. It is a long-lasting solution
a water-repellent efflorescence reducing-
that is ideally suited to precast applica-
agent, manufactured by Chryso.
tions such as roof tiles. The admixture
Efflorescence is an aesthetic problem
reacts with the cement matrix, creating
which presents as a white, chalky deposit
a polymer network that fills the capillar-
on concrete. It is caused by the migration
ies with concrete thereby preventing the
of soluble salts (capillary action) to the
migration of soluble salts to the surface.
surface where it crystalises to form an unsightly sediment.
“A cid w ashing is th e tr a di tion al approach to preventing efflorescence in
“Although ef florescence causes no
the precast industry. However, it is not
structural damage and is often removed
ideal because of potential health, safety
by the natural process of weathering (like
and environmental issues. Sustainability is
rainwater washing over tiles), Coverland
fundamental to Coverland and we respect
is taking taken every possible step to
the environment in our manufacturing
counteract it. We pride ourselves on our
pr ocesses. CHR Y SO®Par ef lo 20 has
quality and our roof tiles must be flawless.
assisted us in adhering to this principle.
Ef florescence occurs most commonly
“In addition to possible health and envi-
during the first week after production,
ronmental threats, acid washing also slows
the period when they are usually delivered
the production process. By contrast, by
to our customers,” explains Willem Grove,
using a minimal amount of CHRYSO®Pareflo
marketing manager of Monier South Africa.
20, the production process is faster and
Willem Grove, marketing manager of Monier South Africa.
safer. There is also a significant cost benefit involved,” says Grove. Another impor tant function of CHRYSO®Pareflo 20 is that it acts as a water repellent because it reduces capillary absorption. Coverland’s rain test involves
running water for two hours
over16 roof tiles. With tiles produced using CHRYSO®Pareflo 20, there is a noticeable water-beading effect and this helps to ensure that water penetration is kept to minimum acceptable standards. An
Coverland’s ‘Rain Roof Test’.
added
benefit
of
using
The tile on the left was manufactured without CHRYSO®Pareflo 20 and the tile on the right was manufactured with CHRYSO®Pareflo 20.
CHRYSO®Pareflo 20 is that tiles have a
always strives to create products with
much richer colour.
the lowest environmental footprint and
“A s the oldest concr ete r oo f tile
the highest quality. CHRYSO®Pareflo 20
manufacturer in South Africa, Coverland
is a way to achieve this,” concludes Grove.
PRECAST VOLUME 6 • ISSUE 1 • 2012
28
CMA MEMBERS
PRODUCER MEMBERS M = Masonry
COMPANY NAME
P = Paving
Pi = Pipes
TELEPHONE
ARW Concrete Holdings
(082) 850 3512
A Fick Cement Works Bafokeng Concor Technicrete Baybrick Beta Tiles
R = Retaining Blocks
PRODUCT
S = Floor Slabs
COMPANY NAME
T = Roof Tiles TELEPHONE
PRODUCT
R
Mobicast Mossel Bay
(044) 874 2268
P
(022) 913 1921
M
MVA
(012) 386 0050
P
(014) 538 0818
MPRT
Monier Roofing South Africa (H.O.)
(011) 222 7300
T
(035) 792 5218
P
Monier Roofing South Africa
(016) 430 8000
T
002634 2925303
T
Monier Roofing South Africa (Free State)
(051) 432 5089
T
Boland Concrete
(021) 875 5365
M
Monier Roofing South Africa (North West)
(012) 250 2218
T
Bosun Brick Brits
(012) 250 1711
P
Monier South Africa (Cape Town)
(021) 534 1441
T
Bosun Brick Midrand
(011) 310 1176
MPR
Monier Roofing South Africa (DBN)
(031) 565 1312
T
Brickcast Industries
(031) 507 5525
MPR
Monier Roofing South Africa (ELN)
(043) 743 2191
T
Brickbuild T/A Panda
Monier Roofing South Africa (George)
(044) 878 1325
T
Monier Roofing South Africa (PE)
(041) 463 2629
T
(046) 624 3377
MPRS
(00267) 244 2106
MP
Cape Brick
(021) 511 2006
MPR
C.E.L. Paving Products
(021) 905 5998
P
Neat Contech
Cast Industries
(011) 316 2375
P
ReMaCon Products
(011) 393 5504
R
Columbia DBL
(021) 905 1665
MPR
Reya Pele Bricks
(016) 363 0340
P
Concrete Units
(021) 386 1923
Pi
Rocla
(011) 670 7600
Pi
Conframat
0861 33 5599
P
Salberg Concrete Products
(011) 357 7600
Pi
Corobrik
(031) 560 3111
PR
Southern Pipeline Contractors
(011) 914 8500
Pi
Deranco Blocks
(041) 463 3338
MR
Shukuma Flooring System
(041) 372 1933
S
Deranco Paving
(041) 933 2755
P
Stanger Brick & Tile
(032) 457 0237
MP
Deranco Precast
(041) 463 3338
S
Stone Age Concepts
(012) 802 1496
P
Eagle Roof Tiles
(044) 874 0290
T
Technicrete
(011) 674 6900
MPRT
Echo Prestress
(011) 589 8800
S
Technicrete (Mpumalanga)
(013) 758 1203
MPRT
(00263) 448 6620
Pi
Technicrete (Mpumalanga)
(017) 689 2100
MPR
Fort Concrete Inca Concrete Products
(021) 904 1620
MP
Technicrete (Mpumalanga)
(013) 696 1153
MPR
Inca Masonry Products
(043) 745 1215
MPRT
Technicrete (Free State)
(057) 391 4200
MPR
Infraset
(011) 876 5500
Pi
Technicrete (North West)
(018) 790 4380
MPR
Infraset
(012) 652 0000
MPR
Technicrete (Limpopo)
(015) 293 8083
MPRT
Infraset
(031) 569 6900
PR
Technicrete (Gauteng)
(011) 203 7700
MPR
(00267) 392 2850
MP
Technicrete (North West)
(018) 484 6234
MPR
(021) 875 5151
R
Technicrete (E.Cape)
(041) 372 2230
MP
(00267) 393 2850
Pi
Topfloor
(021) 951 7700
S
Lategans Cement Works
(021) 873 1154
M
Vanstone Precast
(012) 541 2056
PR
Marley Roofing
(011) 316 2121
T
Vibro Bricks
(012) 374 0205
P
Marley Roofing
(013) 933 3351
T
Western Granite Bricks
(021) 904 1620
M
Marley Roofing KZN
(032) 944 4155
T
West End Cement Bricks
(011) 851 1098
P
082 324 7277
T
Kwena Concrete Products Klapmuts Concrete & Cape Retaining Kwena Rocla
Marley Roofing Cape Town
PRECAST VOLUME 6 • ISSUE 1 • 2012
CMA MEMBERS
29
ASSOCIATE MEMBERS
COMPANY NAME
TELEPHONE
ARQ Consulting Engineers
(012) 348 6668
ILIFA Africa Engineers
(016) 981 0591
J C Paving Consultant
(011) 431 0727
Pipes
(012) 644 0043
Sekhukhune and Associates
(012) 993 4776
SNA Civil & Structural Engineers
(012) 842 0000
Terraforce
(021) 465 1907
Young & Satharia Structural Civil Engineers
(031) 207 7252
CONTRACTOR MEMBERS
COMPANY NAME
TELEPHONE
Cape Wall
(021) 856 3745
Daron Construction
(034) 955 1333
Decorton Retaining Systems
(021) 875 5155
Friction Retaining Structures
(011) 608 4321
Galaxy Paving
(011) 815 1175
Kalode Construction
(011) 781 3814
Mondo Paving & Retaining Walls
(011) 708 0800
PYW Paving
(031) 763 5771
Roadstone Civil & Paving
(011) 683 7080
SA Paving Gauteng
(011) 483 1350
Vesles Civils
(012) 662 3031
Valcal International
(011) 867 2471
NON-PRODUCER MEMBERS
COMPANY NAME
TELEPHONE
Abel Equipment
(044) 874 1876
Ash Resources
(011) 886 6200
Birkenmayer H
(011) 970 3880
BASF Construction Chemicals South Africa
(011) 203 2400
C&CI
(011) 315 0300
Chryso Southern Africa
(011) 395 9700
Dick King Lab Supplies
(011) 499 9400
Kaytech
(031) 717 2300
Kobra Moulds
(003) 111 356 2460
Manitou SA
(011) 975 7770
Mapei SA
(011) 522 8476
Pan Mixers SA
(011) 397 3754
Rampf Formen GmbH
(0049) 7391 5050 148
Sika South Africa
(031) 792 6500
Soillab
(021) 988 7410
Smartstone
(011) 310 1161
Techincal Finishes
(021) 535 4455
Techmatik SA
+48 48 3690811
PRECAST VOLUME 6 • ISSUE 1 • 2012