PRECAST VOLUME ONE ISSUE 3 • JUNE 2008
• Resevoir built with precast hollow-core slabs • The benefits and design of permeable paving • The use of precast concrete on Gautrain
contents 2
Message from the president
4
New plants will meet rising demand for precast concrete products
8
Echo Prestress opts for Sika ViscoCrete-20HE
8
Civil contractor growing its fleet of Manitous
34
Concrete pipelines boost capacity in Tshwane’s Pienaars River outfall sewer system
36
Inadequate specifications on CRB walling lead to failures
38
South Africa’s first permeable paving contract completed
AGE T S R E LAT A T A ED G N A H 3 Concrete organisations -C 10 E B L L I what they do and who they serve THIS W 40
9
World expert to present at CMA paving seminar
Member details
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
12 20
Why concrete paving blocks discolour
Litigation on failed pipelines looms North American expert
24
Concete roof tiles - the most economical and best looking roofing material
27
Precast concrete delivers on social upliftment
32
Hollow-core slabs offer versatility across numerous applications
e-mail: main.cma@gmail.com
website: www.cma.org.za
Editor: David Beer Tel: +27 11 478 0239, Fax: +27 11 678 0254 email: bigsky@ibi.co.za Advertising: John Cairns Tel: +27 11 805 6742 email: main.cma@gmail.com Design, layout and production: Isikhova Publishing & Communications (Pty) Ltd, PO Box 651793, Benmore, 2010 Tel: +27 11 883 4627 email: communications@isikhova.co.za The views and statements expressed in this publication are not necessarily those of the editor and neither he 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.
2 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
to do. But this approach has proved costly, both environmentally and financially, and things are now changing. Preventing water infiltration places a huge burden on stormwater drainage and in regions of heavy rainfall such as Western Europe, it has contributed to the flooding of major rivers. An answer to the problem was found in permeable paving which, as its name implies, promotes water infiltration. It first saw light of day in Germany some 20 years ago, and today its use is fairly widespread in many parts of the world. The Germans view its implementation very seriously, levying taxes on conventionally paved surfaces. Permeable paving using solid paving blocks was introduced in South Africa last year. I see it playing an increasingly important role in replenishing water tables and removing pollutants (up to 90%) from the water at source. It also makes great economic sense as it obviates the need for building expensive and disruptive storm water drainage systems in established urban areas. Two articles are devoted to the subject in this issue. The first covers new design software, PERMPAVE, which is being introduced to this country later this year by the CMA. It was developed by Australia’s Dr Brian Shackel in collaboration with the University of South Australia and the South African version will use local stormwater data. The second is an extension of the first, having been culled
Message from the president
from a paper delivered by Dr Shackel at this year’s ICCX conference. It examines the finer points of permeable paving design, providing the design engineer with an in-depth understanding of permeable paving design requirements. This year’s ICCX conference, of which the CMA was a co-sponsor, has contributed further material to this issue. It includes an article on the use of precast concrete segments on a section of the Gautrain Rapid Rail Link and another on new testing methods for
The days of indiscriminant resource exploitation are numbered. The
the performance of concrete block pavers. We also run an interview
only ‘commodity’ we appear not to be short of is people.
with ICCX’s international conference organizers.
It is now common cause that everything we do has an effect on
Non-ICCX related material includes: an update on the Virginia
our fragile environment. Understanding the concept, however, is
experimental sewer, the only undertaking of this kind in the world; a
only the first step; the nettle will have to be grasped if meaningful
comparative piece in which the properties and performance of fibre
progress in sustainable life-styles is to be made.
reinforced piping (FRC) and concrete pipes are examined; an article
This will entail measuring all our activities in terms of their
on the extensive use of concrete reinforced block (CRB) walling at
environmental impact or life-cost. In other words man must become
the futuristic Wesbank development in Fairland, Johannesburg; the
adept at eco-costing, so that the environmental as well as financial
use of concrete roof tiles on a major low-cost housing development
costs are weighed up in our day-to-day activities.
in Gauteng; and, in another first for industry, an article covering
Those of us in the construction industry will have to establish the eco-cost of materials and building processes, and once our
the use of hollow-core precast concrete slabs in the construction of a reservoir.
structures are completed, the eco-running expenses. Already
Finally, as this issue goes to press, all entries for the CMA’s
one finds that, if correctly designed, a new building can achieve
Awards for Excellence competition will have been submitted. The
reductions of up to 70% in the consumption of power, water and
judging is taking place in June and the presentation of the national
utilities, and could be eco-rated on those savings.
awards is to be held at The Theatre on The Track on October 11. I’d
Obviously the use of recycled materials is to be encouraged and, in our last issue, we covered a Western Cape-based CMA member who
like to end off by wishing the very best of luck to all participants – may the best teams win.
is using crushed demolition waste to produce concrete bricks. Concrete block paving, one of the pivotal sectors within the CMA, can play a meaningful role in sustainable development. CMA Paving Division members are still primarily focused on producing paving blocks which prevent water from infiltrating into the sub-base layer. It was, and to an extent still is, what our design engineers are taught
Garth Gregory, CMA President
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4 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Obituary - Nick Doulgeris The concrete industry lost a very special person when Nick Doulgeris died on 25 January 2008. Remembered by all as a man of principle and integrity, he had an extensive knowledge of concrete technology backed by a preciseness and thoroughness that made his opinion one to be trusted without question. Commenting on his passing, Garth Gregory,
on mixes. “That was typical of Nick”, he
remarkable and it always surprised me
president of the Concrete Manufacturers
said, “work and his clients were always a
how quickly he was able to produce an
Association (CMA), said: “He is a great
priority for him.”
authoritative report. It was a pleasure
loss to the industry – CMA members
Louis Marais, South Africa’s original
to be associated with him. He was a man
will remember that it was Nick who did
“Mr Concrete Roads”, said: “Nick was one
of honesty and integrity, both personally
a great deal of research on the abrasion
of the smartest concrete technologists
and professionally and I will miss him
resistance of concrete pavers and who
I ever knew. His investigative ability was
immensely.”
developed the steel brush abrasion test.
Graham Grieve, until recently MD of
He also served on the committee convened
the C&CI, echoed these sentiments and
to work on the revision of SABS 1058
added: “You could ask Nick any question. He
where his contribution was substantial
would head straight for his files and would
and significant. He conducted all the
always be able to give you an authoritative
comparative testing of crushing strength in
answer based on his past research. He
relation to tensile strength for the revision,
had a dedication and thoroughness that’s
and his work was, as always, meticulous.”
hard to find.”
Ex-Zimbabwean and past CMA director,
A confirmed bachelor and a very private
John Lane, knew Nick for over 40 years
person, Nick was passionate about motor
and it was he who brought Nick into the
cycles and especially off-road scramblers.
Portland Cement Institute (now Cement
He was very involved with the sport,
and Concrete Instiute) where he did much
helping young riders tune and maintain
of the work for which he is remembered.
their machines, and was instrumental in
Lane explained that Nick grew up in
the establishment of a scrambler track
Zimbabwe and worked for the Ministry of
near Kempton Park. Garth Gregory recalls
Roads in the Central Roads Laboratory.
the many truckloads of soil he delivered
Here he was noted for his in-depth work
to the site to help Nick establish the
on soils and bitumen. When Nick came
sharp undulations characteristic of these
to South Africa in the early 1980s, Lane
tracks.
arranged that he join the PCI laboratory
One of Nick’s protégés delivered a moving
team. “Nick was a man who always gave
tribute at the funeral when he described
120%. He was technically very sound and
how, along with teaching him about bikes,
was forthright in his quiet way in giving his
Nick taught him about life, about honesty
opinion. He would not hesitate to disagree
and decency. “On one occasion I had bought
if he believed that his view was correct –
some spares for my bike and some time
which it often was.”
later I discovered that I had under-paid
At PCI he became known for his dedication
the dealer. Nick insisted that I go back
and diligence, for his willingness to go the
and pay the difference. This was the kind
extra mile even if it involved coming to work
of person he was – absolutely straight,
before dawn or late at night to ensure that
absolutely honest and an inspiration to
his clients got the right answer – and got
who knew him.”
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it on time. John Goodman, an engineer at the C&CI and an erstwhile manager of the PCI laboratory, remembers that while the rest of the lab staff attended a company lunch-time braai, Nick remained in the laboratory to complete work he was doing
Nick was a man who always gave 120%. He was technically very sound and was forthright in his quiet way in giving his opinion.
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6 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Strong demand for infraset’s roof tiles Following its entry into the concrete roof tile market towards
INFRASET’s roof tiles are being produced in a state-of-the-art
t h e e n d o f l a s t y e ar, INF R A SE T B uil ding P r o du c t s h a s
multi-million rand at Rossway, Midrand. The plant, which is initially
experienced surprisingly buoyant demand for its new range of
serving the Gauteng roofing market, is producing two roofing
concrete roof tiles.
profiles, Sunset, a bold roll tile, and Horizon, a flat shingle tile,
Some major housing projects are already being supplied by
and both types are in great demand on the local market. They are
INFRASET. These include: Heritage Heights in Krugersdorp where
manufactured in a range of five through-colours and a selection
100 houses are being supplied with Sunset Multi-Blend tiles;
of vintage multi-colour options.
Finsbury Housing project on the West Rand where 900 houses are
Pre-launch research indicated that roofing contractors,
being roofed with Sunset Slate and Red tiles; some middle income
specifiers and builders were especially enthusiastic about the
townhouse projects in Springs where Sunset Multi-Blend tiles are
introduction of the Horizon flat shingle tile. This was due to
being used; and a Stocks & Stocks project in Rosslyn, Pretoria,
the fact that half tiles are no longer necessary when using the
where 400 houses are being roofed with Sunset Amber tiles.
Horizon, and because of this, it can be installed like any other roof
Marketing manager of INFRASET Building Products, Grant
tile in a straight line as opposed to stretcher bond.
Uys, observes that these early sale successes are extremely
Moreover, INFRASET has overcome certain weaknesses in the
encouraging and demonstrate the market’s willingness to use
design of traditional flat roof tiles by re-inforcing the transversal
fresh products and adopt alternative suppliers.
ribs on the Horizon for extra strength. This makes for better on-site handling and reduces breakages. Roo f ing contr ac tor s ha v e also welcomed INFR A SE T ’s introduction of a modern packaging system in which five tiles are strapped together, thereby reducing breakages during transportation. The five-tile pack is also of great convenience to contractors during offloading, but more especially when the tiles are stacked on trusses and rafters prior to laying. Uys notes that the roof tile plant is setting a high quality standard, one which exceeds requirements set by the South African Bureau of Standards (SABS).
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(Left): Heritage Heights in Krugersdorp where 100 houses are being roofed with INFRASET’s Sunset Multi-Blend tiles.
Gill Owens retires after nearly 30 years with c&ci Well-known construction industry person-
support function, including: the promotion
ality, Gill Owens, retired recently after
of the information centre; production of
close on three decades of service at the
publications, newsletters, and monthly
Cement & Concrete Institute (C&CI).
reports; public relations and maintaining
Gill joined C&CI as librarian in 1978 when
the C&CI website. She also edited Concrete
the Institute was known as the Portland
Trends, the C&CI’s quarterly journal which
Cement Institute, and based in Richmond,
received a 2007 “Highly Commended” Sappi
Johannesburg.
PICA Award.
“In those days we still used typewriters
In her retirement, she will run Gill Owens
and operated with manual indexing and
Editing Services, and will continue to edit
cataloguing,” said Dr Graham Grieve, MD
Concrete Trends. She is currently also
of C&CI, at Gill’s farewell function.
engaged in the latest revision of C&CI’s
Mar ke ting the libr ar y, w hich was computerized in 1989, was very important
definitive reference publication, Fulton’s Concrete Technology.
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to Gill and, as chief librarian, she started the concept of open days in 1992. Af ter her appointment as C& CI marketing services manager in 1999, Gill assumed responsibility for the marketing
(Right): Gill Owens, who recently retired after nearly 30 years at the Cement & Concrete Institute, is pictured with C&CI MD, Dr Graham Grieve, after C&CI officially said farewell to her.
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 7
Gautrain sleeper delivery on track INFRASET Infrastructure Products is on schedule with the supply
turnout and B70 sleepers already supplied, they will include 1 in
of Gautrain’s concrete sleepers to the Gautrain Sleeper Joint
12 and 1 in 18.5 turnout sleepers.
Venture. These include B70 sleepers for the ballast track as well
The standard gauge 2.5 metre B70, which is designed for
as sleepers for the 1 in 9 turnouts. Moreover, all the sleepers
high-speed lines, is used widely in Europe where over 40 million
for the Marlboro depot have been delivered.
have been installed to date.
INFRASET, which won the contract to supply both track
Kobus Burger, general manager railway products at INFRASET,
and turnout sleepers against stiff international competition,
says the turnout sleepers are also being manufactured to European
is supplying a total of 190 000 sleepers manufactured to the
specifications and standards for high-speed passenger lines.
Bombela Consortium’s requirements. In addition to the 1 in 9
“We received the coordinates for the turnout sleepers from VAE South Africa during September last year and delivered the initial sets during the first week of December. VAE South Africa sets extremely high standards and specified that the sleepers be manufactured to tolerances of .25 mm.” Burger observed that two notable milestones are integral to the railway line on this project. “It is the first time that swingnose crossings have been used on 1 in 9 turnouts in South Africa and it is also the first time that rail cant is being deployed on 1 in 12 and 1 in 18.5 turnouts.”
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(Left): The first 1 in 9 turnout set manufactured by VAE South Africa for the Gautrain Rapid Rail Link project shortly before delivery to the Gautrain Sleeper Joint Venture. The set was assembled using highly specialised concrete sleepers manufactured to a tolerance of .25mm by INFRASET Infrastructure Products.
Quality CONCRETE
PAVING PRODUCTS
Postal Address: P.O. Box 418, Halfway House, Midrand, 1685, South Africa Physical Address: 38 Spanner Road, Clayville, Ext. 11, Midrand Tel: +27 11 316 2375 | Fax: +27 11 316 2394 E-mail: castind@mweb.co.za
8 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Building a pool between a rock and a hard place A good example of a CRB (Concrete Retaining Block) system
The supporting structure consists of a level foundation which
flexible enough to handle the challenges of a demanding site in an
was built on an outcrop of sloping and uneven granite. It involved
attractive and creative way is to be found at an upmarket guest
some core drilling and epoxy grouting of Y16 starter bars.
house in Sunset Close, Llandudno, Western Cape Peninsula.
Thereafter a reinforced concrete foundation was cast in steps
The project entailed building a CRB supporting wall using
which matched the height of the Terraforce blocks.
Terraforce’s L12 blocks. It provides support to a swimming pool
The first three metres of the wall was built using a concrete-
which is situated on an outcrop of granite. The pool was built by
filled double skin with steel reinforcing in the inner skin. The
Cape Town-based Suburban Pools, one of the top award-winning
subsequent two to three metres were built with a concrete-filled
NSPI pool companies, and the wall was completed by Decorton,
single skin. Because the wall was higher than 1.2m an engineer,
a Cape Town-based specialist contractor for segmental retaining
Fred Laker, designed and supervised the installation.
wall installations.
Reinforcing geogrids were locked into the blocks, embedded in a four percent cement stabilised backfill and tied again to sand bags filled with a specified cement-sand mix. These sandbags were effectively used to shape the pool. Once the pool was completed local contractor Philip Goode, from Timber Tech, added an IPE (Brazilian walnut) contemporary deck in Brazilian walnut. The Terraforce CBR system is also often used to create additional backyard space, for example, for swimming pools. Photo 2 shows an installation using Terraforce L11 Rockface blocks. By using the blocks, builders were able to provide a level, spacious platform that is about three metres above road level and surrounds a house that was built on a steeply sloping property. Flower beds and steps were used in the design to soften the walls. A four metre wall at the back (the cut section) of the property was constructed to provide a large backyard area where a swimming pool was built by Pleasure Pools. The wall behind the swimming pool was embellished with an artificial rock waterfall, along with more plantable space to soften the hardness of the very high rock-face wall. The round curves and landscaping in and around the house ensures that this retaining installation provides both a practical and attractive end product.
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(Above left): Terraforce L11 Rockface blocks were used here to create a level platform for a swimming pool. (Left): This CRB wall, built using Terraforce L11 blocks, is situated in Llandudno, Western Cape Peninsula.
Sikaquick–2500 - quick fix now a durable fix SikaQuick–2500 is now available from Sika South
surface preparation, the product is mixed into
Africa. A single component cementitious patching
the required amount of water using a slow speed
material for concrete, it sets very rapidly and
mixer to prevent air entrapment. Due to its rapid
attains a high and early strength. These features
setting capabilities, the product pot life is 15
make it ideal for use on highway overlays, structural
minutes. Standard concrete curing practice is
repairs for concrete roadways, parking structures,
recommended after which the repair mortar can
bridges, ramps and dams as well as for repairs to
be over-coated with either a protective coating,
industrial floors where down-time is critical.
surface levelling compound, epoxy or a wide range
SikaQuick-2500 allows foot traf fic over the r epair ed ar ea af ter 45 minutes and vehicular traffic after an hour at 25ºC. Following thorough
of other products. For further information on Sika products and systems, visit www.sika.co.za.
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PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 9
Cma publishes leaflet on D.I.Y. crb wall construction GENERAL INSTALLATION GUIDELINES FOR GARDEN WALLS (LESS THAN 1,2M HIGH)
The CMA (Concrete Manufactur-
world, because of their relatively low cost and their ease and
ers Association) has published a
speed of construction. An ability to conform to any contour and
step-by-step instruction leaflet
their suitability to the growth of shrubs, plants and flowers are
on how to build concrete retain-
additional factors responsible for their widespread use.
ing block (CRB) walls correctly.
procedures are followed to ensure that walls provide many
at CRB contractors and DI Y
years of trouble-free service. All too often we hear of and
people who would like to shore
witness cases where the correct procedures have not been
up or create space in gardens
followed with the result that these walls are prone to structural
and other areas with retaining
failure during the rainy season.”
walls no higher than 1.2m. The leaflet begins with the laying of foundations, covering trenching Block D, Lone Creek, BlockWaterfall D, Lone Office Creek,Park, Waterfall Bekker Office Road, Park, Midrand Bekker Road, Midrand PO Box 168 Halfway PO Box House 168 1685 Halfway House 1685 Tel +27 11 805 6742, Tel +27 Fax 11+27 80586 6742, 524 Fax 9216 +27 86 524 9216 e-mail: main.cma@gmail.com e-mail: main.cma@gmail.com website: www.cma.org.za website: www.cma.org.za
“H o w e v e r, i t is cr u ci al th a t th e c o r r e c t d e sign an d
The two-sided leaflet is aimed
and foundation material. Instructions are also given on
laying the first course of blocks and subsequent layers.
The leaflet also lists the CMA producer and contractor membership lists with telephone numbers. Cairns says walls higher than 1.2m require an engineer’s design and on-site supervision, and a manual and audio visual on CD covering the construction of these structures is also available from the CMA at no charge.
Six illustrations come with the leaflet. These include: a typical
The CMA promotes the proper installation of CRB walls on
section through a CRB wall; a closed-face configuration; an open-
an ongoing basis both through the material discussed above
faced configuration; the installation of a base layer; the installation
as well as through seminars, which it holds countrywide on a
of an additional layer; and a completed retaining wall.
regular basis.
CMA director, John Cairns, says CRB walls provide an economical and attractive earth retaining system. “CRB walls are becoming increasingly popular throughout the
Anyone interested in any aspect of CRB wall installation should contact Pam Zukor at the CMA on (011) 805 6742 or on main.cma@gmail.com.
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10 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Following an announcement last year that it would be servicing the SADC region, multinational construction chemicals group, Mapei, held its official launch during ICCX (International Concrete Conference
Mapei launches sadc initiative at iccx conference
and Exhibition) at Sun City in February. With annual global revenues in excess of R16 billion, Mapei highlighted its intention of becoming a major player in the region when eight senior executives came to South Africa to participate in the launch. Meeting and networking with construction prof essionals at the ICCX, the highpowered delegation included Mapei’s CEO, Dr Giorgio Squinzi, operational marketing & communication director, Dr Adriana Spazzoli, strategic planning director, Veronica Squinzi, strategic marketing director, Walter Nussbaumer and export area manager Derk Borneman. Mapei’s innovative and comprehensive r ange o f au x iliar y and enhanc emen t materials for the construction industry attracted wide interest from conference delegates and visitors.
applies to all the other countries. ECS is
(Above): Seen here (from left) at the official Mapei launch at the ICCX are: Dr Giorgio Squinzi, Mapei’s CEO; Pieter Aucamp, ECS; Dr Adriana Spazzoli, Mapei’s operational marketing & communication director; Derk Borneman, Mapei’s export area manager; Christo van der Merwe, general manager, ECS; Giulio Morandini, Mapei; Gianni Sicuro, Mapei; Antony Offenberg, ECS.
In an address to conference delegates,
staffed by local people well versed in the
Dr Squinzi noted that Mapei was involved
requirements and idiosyncrasies of the
in the huge wave of construction growth
local construction industry. Products
currently underway in eastern European
currently being supplied locally include
c oun tr ies such as P oland, Hungar y,
admixtures for concrete, products for
Rumania, C z e ch R epublic, and mor e
construction, and cementitious and resin
of the group has been founded on three
especially Russia, where the growth in
floor coatings.
pillars, namely, specialisation, a strong
demand for Mapei’s substantial product
“Our entry into the southern African
range, is the world’s highest. The group
market means that we have extended our
currently operates through 50 associate
global reach. Worldwide we deliver 16 000
“Five percent of the group’s turnover
companies with 47 production facilities
tons of product to 40 000 customers
is spent on research and development
across 33 countries worldwide.
daily,” Dr Squinzi observed.
in cooperation with many of the world’s
international presence, and research and development.
Dr Squinzi was introduced to a large
During his address Dr Squinzi announced
major universities and we were the first
gathering of conference delegates by
that Mapei would be building a local
to introduce PCE admixtures to the global
Aveng Group CEO, Carl Grim, who spoke
manufacturing facility in line with Mapei’s
market. We have also introduced new
briefly about Mapei’s joint venture with
policy of manufacturing in the countries
products to many other countries, and
Aveng. Dr Squinzi noted that there is huge
it serves. The local plant will be Mapei’s
our Norwegian operation was the first to
growth potential in the local construction
47th, and like all its other factories, it will
introduce several new products in that
industry and that he wanted Mapei to
comply with ISO 9001 standards.
part of Scandinavia,” said Dr Squinzi.
participate in and contribute to it.
“We believe in situating our factories
Seven Mapei R&D laboratories are
“We have signed a local distribution
close to our customers so that they
operated worldwide, two in Italy, and one
agreement with the Aveng Group and a
can be provided with the lowest possible
each in France, Germany, Norway, Canada
comprehensive range of enhancement
costs and the quickest possible delivery
and the United States. Of the group’s
products for the construction industry is
times.”
5 300 employees 12% work in R&D.
already being distributed by its subsidiary, Engineered Concrete Systems (ECS).
Mapei has grown from a small family-
Mapei is also a generous patron of
run business f ounded in 1937 by Dr
cultural and sporting events. It sponsored
“Mapei operates on a local expertise
Squinzi’s father, into a major multi-national
two social events at ICCX, a bush braai and
and management system and therefore
concern. However, despite its size it is still
the main gala dinner, and more notable is its
we are South African in South Africa, as
controlled by the Squinzi family.
sponsorship of Italy’s national soccer team,
we are Italian in Italy. The same principle
Dr Squinzi observed that the success
which won the World Cup in 2006.
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12 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Cma introduces block masons’ site manual The Concrete Manufacturers
The next section cov-
Thereafter, the manual covers serv-
A sso cia ti on ( C M A ) h as
ers modular planning, block
ices in block work, roof and floor fixing,
published a ‘Block Masons’
types and their modular
partition walls, under-floor slabs, trusses
Site Manual’. Over 80 pages
dimensions, as well as the
and rafters, the 140mm modular wall-
of practical information, its
design of a modular 40m²
ing system, and exterior/interior skim
chief objective is to improve
house. Several bonding pat-
plaster. The penultimate section, headed
the understanding of modular
terns are demonstrated,
‘Key technical information’ covers build-
masonry construction and
including stretcher bond,
ing hints, lime in masonry construction,
to pr omote its corr ect
stack bond, quarter bond
and characteristic compressive strength
implementation thr ough
and others. Wall sections
information.
good building practice.
with modular dimensions
The final three pages are devoted to
and wall pier options are
55 definitions and these cover all aspects
also illustrated here.
of the technical terminology covered in
Compiled and co-edited by masonr y consultant, Günter Koch, the manual
Footings and foundations
the preceding pages.
is aimed at both skilled and unskilled brick
are covered in the third section, and layout
Koch says one of the recurring problems
layers, providing guidance in building to
and detailing in the next. Layout and
in South African modular masonry is to
specified standards.
detailing is broken down into the following
be found in making the proper selection of
Koch says much of the detail provided
headings:
mortar and plaster aggregates, as these
in the manual is based on internationally
• Corners
differ from region to region.
accepted modular masonry standards.
• Wall dimensions
The first section illustrates block laying
“This requires local knowledge and
• Intersecting walls
ex p er ienc e in sele c ting the c or r e c t
technique using 51 photographs. These
• Lintels and reveals
proportioning and mixing procedures, as
cover all aspects of block laying technique,
• Coping and piers
well as in curing properties and correct
including block module spacing, the posi-
• Closing cavities
application.”
tioning of first corner blocks, and align-
• Fire protection of steel columns
ment, among others. Jointing and various
• Control joints
contact Pam Zukor on (011) 805 6742 or
plastering techniques are also covered.
• Reinforcing of block work
via email on main.cma@gmail.com.
For a free copy of the publication P
Concor Technicrete permeable pavers used in Durban Concor Technicrete Aqua Trojan permeable
Project manager, Wayne Jordaan of Key
commercial and industrial purposes, with
paving blocks were used in the construction
Projects, said the local municipality had
the result that there is now much more
of a permeable paving surface for a 480m²
imposed flow restrictions on the municipal
storm-water run-off.”
pedestrian pr ecinct and car park at
storm-water network and had specified
Kensington Boulevard in Durban North.
attenuated storage for the site.
The sub-base below the paved surface
“However, there was very little land
acts as a reservoir and during heavy rain
available for storage of sufficient capacity,
at least 60% of run-off surface water is
and a permeable paving alternative was
captured.
recommended by the engineers.”
The sub-base comprises a foundation
The benefits of this Aquaflow system
layer of compacted 63/10mm stone and
extend well beyond the sub-base reservoir.
above that there is a mesh lining, a 100mm
It also receives run-off from other parts of
layer of 20/4mm compacted stone, a geo-
the site, entering through the side of the
fabric liner, 50mm of compacted 6mm
reservoir and being distributed over its
clean stone, and finally, the paving blocks
length via a perforated pipe.
themselves.
Detailed environmental impact research
Tony Bezuidenhout, managing director of
w en t in t o th e p r oj e c t a c c or ding t o
the main conctractor, Model Contracting,
Alistair Avern-Taplin, a director of civil and
said soon after the project was completed
construction engineers Arup.
the system proved itself during some exceptionally heavy and prolonged rain.
“Many former residential areas, such as this particular site, have been rezoned for
P
(Below): Kensington Boulevard, Durban North, where Concor Technicrete’s Aqua Trojan paving blocks were used for a permeable paving system.
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 13
Chryso S.A. establishes production facility in kzn Leading admixture producer, Chryso SA, has invested in a production facility in Durban to augment its manufacturing capacities in Johannesburg and Cape Town. Chryso SA managing director, Norman Seymore, says KZN production will be on stream in Durban at the end of the first quarter of 2008.
“Soaring demand for Chryso admixtures in K ZN f r om major inf rastructural developments, such as the many Durban harbour expansion projects, and the 2010 Soccer World Cup stadium, has made local production in KZN essential. The new production facility will also reduce supply pressure on our head office in Jet Park,” Seymore says. “The elimination of much of the road transportation of admixtures between Jet Park and Durban will also play a positive environmental role by reducing Chryso’s carbon footprint on the busy highway between Gauteng and KZN.” Chryso SA had earlier this year already started investing in an improved service to its KZN customers through the increase of its provincial sales force and the acquisition of a new tanker for bulk deliveries. “The new Durban production capacity will be equivalent to that of Cape Town,” Seymore states. Chryso SA – a subsidiary of the Materis
Group in France - is currently in its 11th year of operations, but French investment in South Africa began as far back as the 1980s when a Chryso distribution licence was awarded to Chemrite SA. Chryso later awarded the distribution of its products to Contech – a company subsequently acquired by Chryso. In 1999, Chryso acquired the admixture operations of Fosroc, a move that ultimately established Chryso as a leader in admixture supply in southern Africa. In addition to three production facilities (once the KZN plant starts manufacture), Chryso SA also has a branch office in Port Elizabeth, which has been the major supplier of admix tur es to the Coega harbour project. P
(Left): Work in progress on the new 2010 Soccer World Cup stadium in Durban. The multi-million rand project is just one of many for which Chryso S.A. has supplied admixtures for the concrete formulation.
14 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Cellulose fibre reinforced cement fails University of Pretoria strength tests as a gravity piping material Tests conducted by the University of Pretoria’s Civil Engineering Department, reveal that the crushing strength of cellulose fibre reinforced cement (FRC) as a gravity piping material fails to meet several requirements laid down by SANS 819:2001 (Edition 3.2) for this type of gravity conduit. The P.I.P.E.S Division (Pipes, Infrastructure Products, and Engineering Solutions) of the Concrete Manufacturers Association (CMA) believes FRC pipe has several other shortcomings referred to in this article, which cast doubt as to its role as a gravity piping material and has submitted related comments to the South African Burea of Standards (SABS). Furthermore, the CMA’s P.I.P.E.S Division is of the opinion that some of the claims about the performance of FRC gravity pipes appear to be at odds with some reputable information sources.
minimum crushing strength required for Series 4 pipes with a nominal diameter of 300mm is 7.0kN (36kN/m) and only one of the four sections tested met this standard. Table 1 below gives the measured properties of the pipes used for testing purposes. Table 1: Measured properties of pipes.
Sample
OD (mm)
ID (mm)
Length (mm)
Wall (mm)
Dry Weight (kg/section)
Wet Weight (kg/section)
Moisture absorption (%)
A1
677
603
300
36.4
37.8
41.8
10.6
A2
678
603
305
36.2
37.1
41.6
12.3
A3
676
603
293
36.6
37.1
41.2
11.0
A4
677
603
303
36.3
37.8
41.8
10.7
B1
501
450
298
24.3
20.0
21.2
6.2
B2
501
450
298
24.5
20.0
21.4
7.2
B3
501
450
300
24.5
20.1
21.4
6.5
B4
501
450
301
24.3
20.2
21.5
6.5
C1
346
301
196
21.2
7.2
8.2
13.2
C2
346
302
198
21.2
7.3
8.2
12.9
C3
346
301
197
21.2
7.2
8.2
13.9
C4
345
301
199
21.4
7.5
8.4
12.1
D1
236
200
195
17.8
4.0
4.6
14.9
D2
236
200
200
17.7
4.2
4.7
13.7
D3
236
200
202
17.5
4.1
4.7
14.4
D4
237
200
200
17.6
4.1
4.7
14.5
These claims
are discussed herein. FRC was first introduced in the 1980s to manufacture asbestos-free flat sheets and has subsequently been applied to gravity pipes and other products previously manufactured with asbestos. Semi-rigid FRC piping was recently introduced with wall thicknesses up to 20% thinner than gravity piping made of steel reinforced concrete. The tests conducted at the University of Pretoria centered on the crushing strength of 24 FRC pipe samples using SANS 819 (Edition 3.2) as the standard. Conducted in September 2005, the tests used sample material which included 200mm long pipe sections with nominal diameters up to and including 300mm, and 300mm long sections with diameters in excess of 300mm. Table 1 of SANS 819 (Edition 3.2) gives the required crushing strengths for the standard Series 1, 2, 3 and 4 as 40, 60, 90 and 120 kN/m2 respectively, when they have been in water for at least 48 hours. It should be noted that these are ultimate requirements and not proof load requirements, as given by the standard D-Load requirements for steel reinforced concrete pipes. When the ratio of ultimate to proof load of 1.5, as recommended in the Nutec
Sixteen pipe sections were tested wet and these tests
literature, is taken into account the equivalent D-Load values are
indicated quite clearly that FRC pipes are significantly weaker
27, 40, 60 and 80kN//m2 respectively .
when wet. They were able to support a crushing load in excess of
Based on the SANS 819 standard, a pipe with a 600mm nominal
15kN/m but were unable to achieve anywhere near the requisite
diameter should take a load of at least 7kN (24kN/m) for Series 1
crushing strength standard of 45MPa. These tests were repeated
and 11kN (36kN/m) for Series 2 pipes and only one of the 600mm
on dry pipes, none of which had the requisite strength of 50MPa.
FRC Series 2 pipes tested met the crushing requirement. The
In fact the best result achieved was 41.8MPa.
16 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
For the wet and dry test results refer to Tables 2 and 3 below.
None of the pipes tested had a strength as high as 50 MPa and the highest strength calculated for the pipes that were tested
Table 2: Strength of pipes tested wet.
dry was 41.8 MPa. These results do however clearly indicate that
Sample
ID (mm)
Length (mm)
Wall (mm)
Failure load (N)
Strenght (MPa)
A1
603
300
36.4
10800
16.23
A2
603
305
36.2
10400
15.53
A3
603
293
36.6
10600
16.18
A4
603
303
36.3
12000
17.95
B1
450
298
24.3
10700
26.95
B2
450
298
24.5
10200
25.29
B3
450
300
24.5
10900
26.84
B4
450
301
24.3
10700
26.58
C1
301
196
21.2
6100
21.06
C2
302
198
21.2
6500
22.18
C3
301
197
21.2
6800
23.25
C4
301
199
21.4
7200
23.94
D1
200
195
17.8
7650
25.59
D2
200
200
17.7
8100
26.84
D3
200
202
17.5
7600
25.34
D4
200
200
17.6
7500
24.99
the pipes are significantly stronger when tested dry than when tested wet. The dry behaviour is significantly more brittle as can be seen from the comparative graph in Figure 1 below.
Figure 1: Crushing of wet and dry pipes.
It is often assumed that, because FRC piping is lighter it can be installed faster. This is not necessarily the case. According to the CMA’s P.I.P.E.S Division, FRC pipes can often take far longer to install, especially if the installation takes place in poorly bedded installations or unstable soils. Unlike concrete pipes which are largely self-supporting, FRC pipes require support from the surrounding soil. Furthermore, FRC pipes are made in five metre sections and weigh essentially the same as the 2.5m sections in which concrete pipes are manufactured. This means that the same equipment is required for the installation of both types of piping. Other claims made about FRC pipes are that they offer
Table 3: Strength of pipes tested dry.
Sample
ID (mm)
Length (mm)
Wall (mm)
Failure load (N)
Strenght (MPa)
A5
603
302
34.6
14400
23.7
A6
603
300
34.4
14200
23.7
A7
603
300
34.0
12100
20.7
B5
450
301
24.6
12900
31.3
B6
450
301
24.6
12700
30.9
superior chemical and abrasion resistance, better hydraulic characteristics and design parameters. In fact, according to the CMA, FRC piping absorbs much more water than reinforced concrete (RC) piping and is therefore more likely to be vulnerable to penetration and attack by aggressive chemicals. Tests conducted by the University of Texas at Arlington, USA, in which actual service conditions were simulated, indicate that FRC pipes lose up to 4.8 times more wall thickness than RC pipes. The CMA’s P.I.P.E.S Division says that because FRC pipe is usually 20% thinner than an RC pipe, any decrease in wall thickness
B7
450
301
24.4
12800
31.5
C5
301
202
21.3
9300
30.6
C6
302
200
21.3
9000
30.2
C7
301
200
21.6
12800
41.8
D5
200
198
17.8
11300
37.2
D6
200
197
17.6
11000
37.1
D7
200
199
17.5
10800
36.6
is liable to have a far more damaging effect on structural strength properties. Moreover, the Division notes that excessive abrasion at the entrance to storm water systems will also have a detrimental effect on hydraulic capacity. Abrasion resistance, wall thickness, strength specification and a factor of safety on FRC piping are all elements which should be, but are not clearly spelt out by FRC manufacturers. It is said that FRC piping has a low manning value of n = 0.011 and that this ensures vastly improved hydraulic characteristics over RC piping. In reality the manning ‘n’ value for RC pipe is
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 17
also 0.011. However, due to the fact that designers must take
reinforced of pipes up to 1 000mm diameters. There is no standard
the difference between laboratory testing and actual installed
for larger diameter fibre reinforced pipes.
conditions into account, ‘n’ values of 0.012 and of 0.013 are usually specified for actual designs using both materials. A safety factor of 1.5 is claimed for FRC pipes thereby offering “the specifier a safe, proven alternative which will perform under
Reinforced concrete pipes have a proven life of 100+ years and the structural performance is not influenced negatively by wet conditions. On the contrary, concrete strengths improve in wet and moist conditions.
P
high loading conditions”. The CMA’s P.I.P.E.S division says much of this safety margin is required to compensate for the fact that the safety factor is only based on a proof load as opposed to an ultimate load. Furthermore, it says it is well documented that FRC pipes lose strength when wet and suffer long-term strength loss under sustained loading. S A NS 819:2001 r equir ements call for strength loss to be no greater than 5%. In Australia FRC piping manufacturers indicate a loss of 50% when their piping is immersed in water and subjected to sustained loads. According to the CMA no specification exists for the types or quality of fibre used in the manufacture of local FRC piping. The reinforcement of the piping is therefore not specified at all. By contrast all the constituent materials, for example, sand, stone, reinforcement and cement, are specified in reinforced concrete pipes. Another concern is that SANS 819:2006 only applies to fibre
(Above): A typical concrete pipe installation.
Lindley, a small town in the eastern Free State, is where South Africa’s first complete reservoir (wall & roof ) was erected using precast hollowcore concrete slabs. A skills shortage, especially of concrete specialists and shuttering expertise, led to a decision to extend precast slab technology, which has already been successfully used on reservoir roofs, to the walls. Besides negating the skills shortage, opting for the precast route meant substantial cost and time savings, while simultaneously guaranteeing consistency in the quality and requisite properties of the walls.
outer ring beam 400mm wide x 500mm deep and projected 300mm above the concrete floor to provide adequate shear resistance to the reservoir walls. The 150mm thick reinforced concrete floor was cast in four strips and the joints were sealed with horizontally positioned rubber water stops. Wall slabs were supplied by a CMA member company, Bloemfontein-based Stabilan. Based on hollow-core prestressed
The Lindley reservoir forms part of the
equipped and had access to the necessary
technology, each wall slab measures 1.2m
Government’s programme of bringing water
sk ills. A s things stood at L indley it
x 4.5m x 250mm thick and is rated at a
and water-borne sanitation to all South
would have taken much longer as neither
compressive strength of 50MPa. However,
African communities. At a capacity of
condition applied.
unlike traditional slabs which are fully
1.2 mega litres, it will supply 950 housing
“Being the first of its kind, this project
hollow-core, the lower 1.2 metre section
units due to be erected on the outskirts of
involved a learning curve for all participants.
of each slab was cast in solid concrete to
Lindley during the course of 2008/9.
Even so, the entire project took only seven
provide additional shear strength. Once
Johann Steyn of MVDxariep Consulting
weeks to complete. And, provided all
installed, the joints between the slabs
Engineers, the company responsible for the
the precast material is to hand, future
were grouted and a horizontally positioned
design and project management said the
reservoir projects using precast slab
steel strap measuring 90 x 8mm was
walls took a mere three days to erect.
technology on the walls, columns, beams
fastened 1 200mm from the top of the
“Had we opted for traditional shuttering
and roofs should take no more than 10
wall to provide ring tension to the upper
it would have required four 1.2m lif t
days to complete once the in situ floor has
section of the wall panels. The inside of the
se c tions, e ach o f w hich w ould ha v e
been constructed” said Steyn.
wall was then lined with 30mm thick gunite
taken about seven days to complete. On
The in situ concrete floor at the Lindley
this basis the whole project would have
reservoir took three weeks to construct.
stretched over six weeks had we been well
I t c ompr ise d a r ein f or c e d c oncr e t e
and painted with a waterproof sealant from Multi Chemical Construction. A n additional ver tically positioned
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 19
circumference as well as two beams
erected in close proximity to the reservoir.
which divide the reser voir into three
The tower, which comprises a galvanised
sections. Each beam is in turn supported
steel tank on a steel frame, rises to nine
by three columns. Measuring 330mm x
meters at its apex. It was installed to feed
330mm and 330mm wide x 1 200mm
the surrounding high-lying areas, which
deep respectively, the columns and beams
due to a lack of water pressure, cannot
were constructed from masonry with in-
be adequately supplied by the reservoir.
fill concrete to utilise local bricklayers.
Both the reservoir and the water tower
T h e b e am s a n d c o l um n s c o ul d h a v e
are supplied by electronically controlled
been replaced by precast components
pumps which in turn feeds all the other
manufactured by Stabilan.
reservoirs in Lindley.
After being placed in position, the roof
Following a path of least resistance
slabs were grouted and covered with a
the pump fills the concrete reservoir
cement screed 100mm thick at the centre
first. However, an over-riding system of
and 50mm thick at its perimeter thereby
electronically controlled valves has been
creating a 50mm drainage slope.
installed to ensure that when necessary,
Steyn commented further that the quality contr ol of concr ete in water
water can be pumped into the water tower before the reservoir.
retaining structures is all important. “On-
CMA director, John Cairns comments
site concrete mixing requires a full-rime
that the Lindley reser voir project is
supervisor to ensure that the correct
further evidence of the versatility of
and consistency and this certainly applied
precast hollow-core slab technology.
at Lindley.”
“Precast concrete is still under-utilised
S tey n f or esees many mor e such
in the country, but engineers are becoming
reser voirs being constructed as the
increasingly attuned to its advantages
G o v er nm en t’s w a t er an d s ani t a ti on
as this project clearly demonstrates,”
programme gains momentum.
says Cairns.
rubber water stop was installed along
“I believe precast slab technology will
the bottom of the inner slab wall. It was
come into its own, especially in small
covered with gunite, half of which was
tow ns and r ur al cen tr es w her e the
imbedded into the floor to prevent leaking
expertise for shutter work is simply not
through the bottom of the wall panels.
available. A different situation applies in
Precast roof slabs, in various lengths
the cities where each project should be
measuring 1.2m wide and 160mm thick,
evaluated on the basis of available skills
were also supplied by Stabilan to cover
and equipment at any given time.”
the 17m diameter reservoir. They are
In addition to the new Lindley reservoir,
supported by the precast walls on the
a 150kl sectional steel pressure tower was
P
(Top left): The completed 1.2 mega litre Lindley Reservoir, with a 150kl sectional steel pressure tower positioned behind it. (Below left): South Africa’s first reservoir under construction using precast hollow-core concrete slabs. (Below right): Stoffel Botha, marketing director of Stabilan, John Cairns, CMA director, and Johann Steyn, senior partner of MVDXariep Consulting Engineers, seen here at the Lindley Reservoir shortly after its completion earlier this year.
20 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Dr Brian Shackel, Visiting Professor, School of Civil and Environmental Engineering, University of New South Wales, Sydney, Australia
This is an edited version of a paper delivered by Dr Shackel at the ICCX Conference held at Sun City in February this year. In it he sketches the history and research background of permeable interlocking concrete paving (PICP) and discusses its environmental and economic advantages. These topics are not fully covered here, nor are the types of PICP pavers, bedding and jointing materials, nor the applications of PICP. They can be studied in the full text of Dr Shackel’s paper which is obtainable from the CMA. This article focuses on the design of PICP and outlines the development of a computerbased mechanistic analysis and design software program, PERMPAVE, which integrates with modern concepts of sustainability and water-sensitive urban design. The design aspect was chosen for this article because it dovetails with another editorial tract in this issue covering the specifics of PERMPAVE software, due to be launched locally in November.
To meet such requirements, best management practices (BMP) include controls for reducing or managing pollutants, procedures for the proper disposal of waste, and
The benefits of permeable paving include
drainage apertures. Where necessary,
the use of flood management procedures
not only stormwater management, pollution
polluted material can therefore be easily
which assess impact on water quality.
contr ol and water r e-use, but o f f er
and economically removed and replaced.
economic advantages by minimising the
However, it is worth noting that, as yet,
when:
costs of surface drainage works, thereby
no special maintenance requirements have
• Stormwater and sewer systems are
reducing the demands on stormwater
materialised. Several European installations
sewerage, and optimising land use. Recent
have been in service for 15 years or longer
• There are limitations on the extent of
studies in the UK have shown that PICP
with only routine maintenance, such as
yields significantly lower initial and whole-
car and bus parking areas at the Prater
• There is insufficient space for both
of-life costs than asphalt or cast-in-
Football Stadium in Vienna.
place concrete surfaces. Initial concerns
Typical regulations for new urban paving
Permeable paving should be considered
close to capacity impermeable cover vehicle use and attenuation ponds
• Water quality and pollution control are
about the long-term maintenance cost
developments may include:
of permeable paving due to clogging have
• Limits on the extent of
largely been allayed through tests in
Europe, North America and Australia.
• On-site retention of rainwater
However, it has also been successful in
• Control of the discharge rate
heavily trafficked applications such as
paving can achieve a service life in excess
• Control of the discharged water quality
container yards.
of 25 years without maintenance, and more
• Measures to reduce sedimentation
importantly, that pollutants accumulate
mainl y in the upper 25 to 50mm o f
• Measures for harvesting and
the aggregate used to fill the joints or
These tests indicate that permeable
impermeable areas
primary design objectives. For these reasons, PICP provides an
option especially relevant to urban roads.
and/or pollution, and, increasingly, re-using rainfall
(Top and above): A close up view of the laid permeable paving stones at a new car park at the University of the Witwatersrand.
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 21
DESIGN OF PERMEABLE PAVING
permeable paving involves two parallel
LOCKPAVE and PERMPAVE provide an inte-
Several distinct engineering requirements
design requirements: structural design and
grated approach to PICP design which can
must be addressed in designing permeable
stormwater management. Each of these is
handle most generic types of paver.
paving. Ideally the methodology should
likely to require a different paving thickness.
embrace the following objectives:
Clearly, the designer must opt for the
1. What is the design life of the pavement?
• Flood mitigation by retention or
greater thickness.
2. How fast can pavement accept
detention (i.e. water quantity)
The principal design questions are:
Software for structural design is already
rainfall? This depends on the paver
• Water quality improvement by filtra-
available as the LOCKPAVE program. A new
type, the crossfall, the bedding and
program, PERMPAVE, was commissioned
drainage materials, and the type of
• Water conservation by collection and
for the hydraulic design by the Concrete
base and sub-base.
Masonry Association of Australia in 2006. It
3. How fast will the pavement drain?
tion or retention (i.e. water quality) re-use (i.e. water harvesting)
• The ability to carry traffic
has been developed by the School of Natural
This is related to the type of base and
An overview of permeable paving design
and Built Environments at the University of
sub-base, the type of subgrade and
is given in Figure 1. This figure shows
South Australia in conjunction with the au-
the position of the water table.
that, in contrast to conventional paving,
thor, the developer of LOCKPAVE. Together,
4. How much water can the pavement
retain and for how long? This will
depend on the thickness and
permeability of the pavement layers.
5. How thick should the pavement be
to carry traffic? Here the resilient
properties of the permeable pavement
materials are paramount.
DESIGN LIFE A major advantage of PICP is that it can trap around 90% of total suspended solid (TSS) pollutants, i.e. particulates. Research shows that particulates gradually accumulate in the pavement, clogging it, albeit slowly. Experimental work conducted at the University of South Australia (UniSA) has established that an effective lifespan of between 15 and 25 years is feasible and it therefore appears reasonable to adopt a 20 year maximum design life for PICP. The remaining questions are addressed through cross section, storm water management Figure 1. Methodology of permeable pavement design.
and structural design.
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24 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
CROSS-SECTION SELECTION
are likely to adopt this approach in the
As shown in Figure 1, the first step in
future. Therefore PERMPAVE does not
PICP design is to determine how the water
currently utilise continuous simulation.
will be controlled and managed within
Rather, the program uses the design storm
the pavement system, and this entails
approach. In time, however, it is expected
choosing the right cross-section and
to move to continuous simulation as local
pavement materials. Broadly three cases
practice changes.
need to be considered:
T he design storm approach meets
1. Where the water is allowed to flow into
curr ent standar ds specif ied by local
the sub-grade and water table. Although
councils. Such procedures are not
sub-surface drains can sometimes be
generally suitable for infiltration system
omitted, they are only feasible on
design. However, research by the South
permeable sandy soils and some
Australian Cooperative Research Centre
local authorities won’t allow them to
for Water Quality and Treatment (CWSS)
be omitted.
has developed simple methods derived
2. Wher e the PICP is f ounded on an
from continuous modelling which can
impermeable clay, subgrade provision
be incorporated into standard design
must be made to drain the water from
procedures.
the site using drainage pipes. Moreover,
Briefly, the design storm approach
a filter fabric must be used to prevent
involves the use of local average storm
clay fines contaminating the base and
intensity bursts for a particular average
sub-base.
recurrence interval (ARI). A storm temporal
3. Where there are contaminated flows
pattern can be applied to the average
or issues of soil salinity. Here an
storm intensity to pr ovide a rainf all
A su r v e y c o n d u c t e d am o n g l o c a l
impermeable liner must be placed
distribution pattern over time. The rainfall
go v er nment engineer s showed tha t,
between the PICP and the sub-grade,
distribution pattern is peculiar to specific
to be adopted, the software needs to
and drainage pipes are required to
geographic zones.
address a number of issues in stormwater
remove infiltration.
Several general methods using
management. Hitherto, most analyses of
Suitable cross-sections and design
nomogr aphs ha v e b een published to
permeable pavements had concentrated
details for achieving these objectives are
design PICP for water management, and
on analysing retention and/or detention
available.
software based on the US Environmental
of stormwater within the boundaries of
Protection Agency stormwater manage-
a PICP site. However, detention must
WATER INFILTRATION AND TREATMENT
ment programme, SWMM, exists for one
be integrated with overall catchment
Three issues must be considered in the
proprietary permeable paver. However,
management in terms of run-of f and
design of pavements. These are:
pollution control and water re-use also need
water quality. In other words, permeable
1. Stormwater management: how much
to be considered to achieve an effective
pavements should not be considered as
water can infiltrate the pavement over
outcome. This is best achieved by specially
stand-alone projects but should form part
a given time and where will it go?
written software such as PERMPAVE.
of managing the whole catchment. Catchments can be lar ge; f or
2. Pollution control: what is the quality of
3. Water harvesting. How much water can
be stored and re-used?
S T OR M WATER M A N AG E M E N T A N D FLOOD MITIGATION There are two methods for designing permeable pavements for flood control: 1. The design storm approach 2. Continuous simulation using historical
ex ample, embr acing en tir e subur bs.
the effluent leaving the pavement?
rainfall data. Designing flood mitigation systems
which use continuous simulation is complex and does not yet f orm par t of local government r equir ements any wher e. However, some countries such as Australia
Designing flood mitigation systems which use continuous simulation is complex and does not yet form part of local government requirements anywhere.
Critical locations, where local authorities regulate flows and/or water quality, are normally found some distance from PICP installations. Therefore, the critical factor is how PICPs impact on catchments beyond and downstream of their immediate locality. This means that stormwater management sof tware must calculate retention and detention, predict outflows and/or drainage times (emptying), and must also provide data to model the permeable pavements as nodes in existing catchment management procedures and software. Similarly, the software must be capable of working with water quality
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 25
Monthly demand characteristics are the main consideration for water harvesting (re-use). Water Management Outputs The range of water management outputs offered by PERMPAVE include: 1. Storage size requirement to achieve
specified performance targets
2. Peak flow rate for selected storm
events at the site
3. Site critical storm duration 4. Average annual reduction in
pollutant load
5. Average annual harvesting/
re-use capability
STRUCTURAL DESIGN A s m e n ti o n e d ab o v e, th e p a v em e n t thicknesses required for stormwater management normally differ from those needed to carry traffic. This means that in addition to water management, traffic flows and loading must be considered in software programs if municipal engineers
• Temporal zone
the structural design. World-wide, PICP
are to adopt it.
• Average storm intensity
has already been successfully used in
• Antecedent condition (e.g. part-full
projects ranging from car parks to roads,
ports and container yards. Accordingly,
To d a t e, m o s t P I C P s t o r m w a t e r management installations have used the
with stormwater?)
design storm approach based on historical
any structural design procedure should be
rainfall records. Arbitrary assumptions
Water Quality, Harvesting
capable of handling a wide range of traffic
about the state of storage in the pavement
and Re-use
conditions while utilising the full range of
– for example, whether they are to be
Water quality and har vesting /r e-use
new materials which are available for the
empty or half-full at the commencement
analysis can be undertaken using a simplified
construction of PICPs.
of a design storm – must be made. The
approach. Hydrological ef f ectiveness
alternative is to use the modified design
curves developed by Argue and Pezzaniti
alr ead y ex ists to achie ve this.
storm method which considers drainage
at UniSA have been incorporated into the
ex ample, L O CK PAV E, use d f or many
time, emptying by either infiltration /
software code. These apply to specified
years in Australia, South Africa and many
percolation or via drainage pipes.
geographical locations such as major cities.
other countries, can model permeable
A simple pollutant removal algorithm is
pavers and permeable base and sub-base
included in PERMPAVE.
materials. Resilient modulus data, such
Therefore the following inputs need to be considered for the pavement: • Effective area ‘connected’ to the
Mechanistic pavement design software For
Two approaches to controlling water
as those summarised above for base
quality can be identified. The first of
materials, can be used by LOCKPAVE
• Proposed area of the permeable
these is to filter the stormwater and
for the design of PICP. This mechanistic
then release it into the local government
methodology therefore complements the
• Impervious area not draining into the
drainage system. The second is to filter
water management methods which are
and r e t ain the stor mwa ter on-si te,
modelled in PERMPAVE.
permeable paving system paving system permeable paving
• Pervious area not draining into the
allowing it to slowly percolate into the
One problem facing the designer of PICPs
underlying soil. Factors that must be
is choosing the moisture content of the
• Permeable paving storage
considered here include:
base and sub-base materials, because this
• Pavement material porosity
• Pollutant input concentration
• Soil saturated hydraulic conductivity
• Drainage outlet discharge
• Pollutant removal efficiency
characteristics
Storm data must include:
• Historical rainfall data
permeable paving
characteristics characteristics
• Average recurrence interval (ARI)
• ‘First flush’ pollutant characteristics
• Critical storm duration
• Build up/wash off of pollutants
(Above): A new car park at the University of the Witwatersrand, which is being paved with a permeable paving system. The picture shows the various layers which make up a permeable paving system, including the sub-base layer of aggregate, a layer of membrane, a layer of fine aggregate, and finally the paving stones, which in this instance were supplied by Concor Technicrete.
26 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
affects the stiffness (Resilient Modulus or,
to some increase in base or sub-base
technique for achieving water-sensitive
Mr) of the materials. The modulus falls with
thicknesses for PICP compared to CSP.
urban design. There is now sufficient data
any increase in saturation, yet most studies
However, as noted above, the final design
to allow the design of PICP for all types of
of Mr have been carried out under relatively
thickness for PICPs is determined by the
applications to proceed with confidence.
dry conditions close to optimum moisture
greater of the two thickness requirements,
The design engineer needs to identif y
content (OMC). General relationships
which is either based on stormwater
retention and detention requirements,
between Mr and moisture content for
management or traf fic loading. In the
pr edict outf lows to the surr ounding
base and sub-base materials, published
author’s experience the thickness needed
catchment, integrate the project as a
by the author in Australia, show that Mr
for water management is often greater than
node in existing catchment management
values at high moisture contents may be
that needed for traffic. This means that
procedures and software, and ensure it is
only 50% or 60% of those customarily
there is usually no economic disadvantage
compatible with water quality monitoring
used in mechanistic pavement design for
in the use of thicker PICP pavers compared
programs. All these factors are rated very
materials meeting current base or drainage
to conventional CBPs, because stormwater
important by municipal engineers for whom
layer specifications. Similar reductions in
considerations often determine the final
water-sensitive urban design is a basic
Mr are found when using scalped granular
thickness. However, it would be unwise
requirement. PERMPAVE is intended to help
base materials. In the absence of Mr
to assume that this will always be the
PICP reach its full potential by embracing
values which have been measured at high
case, especially where heavy traffic must
stormwater management, water quality
saturation levels, choosing Mr values only
be carried. Accordingly, the stormwater
and water harvesting. At the same time
about half those routinely adopted would
design should always be accompanied by a
the software is designed to co-exist with
be prudent.
structural analysis.
the catchment management and water
The use of lower Mr values than are
quality software that is already widely used
commonly selected for the structural
CONCLUSION
in countries which apply the principles of
design of conventional pavements leads
Permeable paving, PICP, is an important
sustainable urban design.
P
ADVERT
28 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
The Virginia Sewer experiment: contributing to sewer design Alaster Goyns – Piping Consultant
Nineteen years ago a 65 metre experimental sewer section was commissioned in Virginia, Free State. It comprised three sets of 900mm diameter concrete pipe, each of which contained nine different types of cementitious materials. During the intervening period valuable information has been obtained by monitoring the performance of these materials, and this information has now been combined with the predictive theory, developed in the United States and known as the Life Factor Model (LFM), to produce a sewer design manual. It will be published later this year by the P.I.P.E.S. Division of the Concrete Manufacturers Association (CMA).
of concretes made with dolomitic
• The pure, or mineral acid attack in the
(DOL) and siliceous (SIL) aggregate
laboratory, showed little correlation
The Virginia sewer operates under very
could be clearly seen. On the former
with the biogenic attack in the
aggressive conditions and is the only such
both the binder and aggregate were
experimental sewer.
experiment ever to have been undertaken
corroded whereas on the latter it was
anywhere under such conditions. At the
the binder only.
outset, predictive theory indicated that
• Concrete made with calcium aluminate
between the performance of the materials
a standard concrete would corrode at
cement (CAC) appeared to be performing
was now more marked. The most significant
a rate of ±6.5 mm per annum whereas
more effectively than concrete made
findings on the unprotected pipes were:
a dolomitic aggr egate concr ete, the
using Portland Cement (PC).
• The PC/SIL concrete was performing
traditional solution for sewer pipes, would
• Although the asbestos fiber rein-
corrode at a rate of ±1.3 mm per annum.
forced (AC) pipes had corroded, the
• The PC/DOL concrete was performing
This meant that the traditional solution,
corroded material did not break off.
better than the PC/SIL concrete
which had pr oved e f f ec ti ve on most
Instead it remained intact but swollen,
but not quite as well as had been
sewers, would not be suitable for a sewer
owing to fibers in the pipe wall which
predicted. This was due to varying
with a life expectancy of at least 40 to 50
held the corroded material together.
rates of corrosion between the
years under such aggressive conditions.
• All the protected pipes performed
aggregate on the one hand and the
Therefore, the project specification called
satisfactorily except where the
binder on the other. Some aggregate
for either a lined concrete or a coated
coatings were damaged.
fallout was also observed.
Alaster Goyns – Piping Consultant
The five-year inspection confirmed the two year findings, but the differences
as predicted.
fiber cement pipe. A by-pass section was
• The CAC pipes were performing better
also constructed so that effluent could be
than the other unprotected pipes and
diverted around the experimental section
certainly much better than predicted.
during inspections.
• The unprotected AC pipes were
performing close to what had been
ROUTINE INSPECTIONS -
predicted providing the depth of the
The First Decade
soft corroded products was deducted
Regular inspections, during which material
from the wall thickness.
losses were measured and gas readings
These findings led a pipe supplier and a
taken, took place. Initially sections of the
CAC supplier to investigate the feasibility
pipes were also subjected to pure acid
of making pipes with a CAC/DOL concrete.
tests in the BOUTEK laboratory at the
T his proved too costly, so a method
CSIR in an endeavor to obtain correlation
of incorporating a CAC/DOL corrosion
be t ween a labor a tor y test and si te
control layer on a host pipe made of PC/
conditions. After two years some clear trends could be identified: • The difference between the performance
(Left): Kassie Botha, who is looking after the project on behalf of Pipes cc, removes the lid of a sample pipe before weighing and checking it for corrosion.
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 29
SIL concrete was developed. This approach has subsequently been applied to many South African sewers since 1997 and their anticipated life is several times greater than those sewers manufactured with the traditional dolomitic aggregate concrete. Based on inf ormation available at that time it was assumed that CAC/ DOL concrete would corrode ten times slower than PC/SIL concrete.
Samples
of CAC/DOL plus other materials were placed in the sewer and their masses were checked regularly as a means of predicting their corrosion rates. It should be noted, however, that mass loss is only an indication of corrosion rate, and should be used in conjunction with the relative corrosion rates of aggregates and binders.
The comparative rates of
mass loss tend to be somewhat lower than actual corrosion rates. As the application of the CAC/DOL layer was a wet-on-wet process and this corrosion control layer was compacted into the host pipe, there was an affective
(Above): A series of 250mm long pipe samples which were placed in a manhole during 2005.
bond and an aggregate interlock between
(Left): A CAC/SIL sample pipe with +- 30mm lost due to corrosion. It was located next to a coated FC pipe with a wall that had swollen from its original thickness of 30mm to 150mm.
the two layers. For many sewers with moderate to severe corrosion the use of this concept of the CAC/DOL corrosion control layer made for a more costeffective solution than either the inert cast
layer its durability requirements, and
in-lining or the traditional dolomitic lining.
providing that operating conditions and
Providing conditions are not excessively
effluent composition have been established,
aggressive, this solution is applicable to
appropriate pipe choices can now be made
pipe diameters of 300 to 1 200mm.
to provide the most cost-effective sewer piping solutions for the requirements of a
The Second Decade
particular sewer. The CMA’s sewer design
After 12 years the deterioration of the
manual will describe how this is achieved.
three siliceous aggregate pipes was so severe that they were on the point of
THE FUTURE - Extending the use of
collapse. To prevent this from happening
the experimental facilities The information obtained to date is limited
sewage was diverted through the bypass section until the necessary remedial work
1.0 for a PC/SIL concrete were:
to a few of the possible materials that
had been done. As had been anticipated, the
• 0.4 for PC/DOL.
could have been used as corrosion control
84mm walls had disappeared completely in
• 0.25 for CAC/SIL.
measures and there is still considerable
some sections, indicating a corrosion rate
• 0.32 for FC.
scope for further refinement. With this in
in excess of 7mm per annum.
• and an estimated 0.09 for CAC/DOL.
mind new 250mm long pipe samples have
The three badly deteriorated pipes
These values can now be used in the
been placed in the manholes that were
plus sections of pipes on either side of
predictive equations of the LFM, developed
constructed in the gaps left by the pipes
them were removed and replaced with
in the US and based on a PC concrete,
that were removed. Placing these pipe
manholes. Detailed measurements were
by adding a material factor equivalent to
samples in manholes introduces a significant
then taken to ascer tain the relative
the relative corrosion rates given in the
change to the way in which inspections are
corrosion rates of the different materials.
preceding paragraph. Given that the host
done as it is no longer necessary to divert
The measured relative corrosion rates for
pipe can meet the structural requirements
the flow through the bypass section. The
the unprotected materials, using a value of
of a sewer and the corrosion control
pipe samples have removable top sections
30 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
(Right): New samples, which were placed in the sewer during 2005, showing signs that corrosion has begun.
inspected and then assessed on a regular basis so that economical rehabilitation can take place and costly emergency replacements avoided. The development of the LFM some 30 years ago provided a tool which is used to predict corrosion potential in a sewer operating under a given set of conditions. The development of better materials, based on the performance of the samples in the Virginia experimental sewer, means that concrete pipes which can handle the conditions in almost any sewer, are now available. Depending on these conditions, in very broad terms this means that in
The development of the LFM some 30 years ago provided a tool which is used to predict corrosion potential in a sewer operating under a given set of conditions.
South Africa: • Traditional PC/DOL pipes with a
sacrificial layer are applicable to 60
to 70 % of sewers up to 1 200mm
in diameter
• Pipes with a CAC/DOL corrosion
control layer are applicable to about
which can be measured and weighed. Such
section of live sewer has been set aside to
30% of the sewers up to 1 200mm
an exercise took place earlier this year and
test the performance of materials under
diameters
indications are that the corrosion loss will
very aggressive conditions. International
• Pipes with cast-in HDPE linings are
be measurable later this year, three years
CAC suppliers have shown considerable
applicable to a very small percentage
after the pipes were installed.
interest in the new manholes and they
of pipes less than 900mm in diameter
The additional samples placed in the
have co-sponsored the construction of a
where conditions are very aggressive
new manholes all consist of unprotected
fourth manhole completed at the end of
and will compete with the other
concrete in three categories, namely:
2007. When used in the LFM, the data
solutions on a project by project basis
• Concrete made using PC cement
gleaned from this project will also be ap-
with pipes from 900 to 1 200mm
plicable to other countries, in particular
in diameter.
• CAC linings integrally cast into the
those with developing economies. Many
• For pipes larger than 1 200mm in
with extenders host pipes
of these are located in warmer climates
diameter most sewers should probably
• and mortar-lined pipes using both PC
where sewer conditions are similar to or
be specified with a cast-in HDPE lining.
and CAC.
even more severe than those experienced
There are two advantages in using
These additional samples are intended
in South Africa.
an HDPE lining on these pipe sizes. The
smoother bore offers greater hydraulic efficiency, hence a smaller diameter can
to yield more accurate information than was the case during the first decade
ADDITIONAL CONSIDERATIONS
o f measur ements. In par ticular, the
Until quite recently sewers were designed
be used, and the cost of the lining
per f ormance of the CAC linings with
for a 40 year lifespan (one generation). This
relative to that of the host pipe
dif f erent aggregates and dif f erent
shortsighted approach, especially when
decreases as the diameter increases.
proportions will be assessed, as will the
applied to sewers and other buried pipelines,
influence of various extenders on the
is highlighted every time a sewer fails.
performance of PC.
T h e S o u th A f r i c an c on cr e t e p ip e industry now supplies a full range of
Current thinking maintains that a sewer
sewer pipes, offering sewer owners and
should be designed for a much longer service
designers the most cost-effective solution
International applicability
life, at the end of which rehabilitation rather
to meet the design life requirements for
of developments
than replacement should be the preferred
any sewer, no matter how aggressive the
Although there has been considerable re-
route. This means that outfall sewers
conditions. They will be further assisted in
search on sewer corrosion internationally,
should not simply be installed and forgotten
making the right pipe choices when CMA’s
South Africa is the only country where a
about. After a certain age they need to be
sewer design manual is published.
P
32 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
For two years running, South Africa has played host to the international construction community by staging two ICCX (International Concrete Conference Exhibition) events, the first in Cape Town last year, and the second at Sun City during February this year. Hosting one, let alone two such events, is something worth crowing about as it emphasises the importance the international construction fraternity attaches to South Africa’s construction boom. Last year’s event attracted 450 delegates and exhibitors and this year the figure rose to 600 of whom close on 80 were exhibitors. More than half the delegates and presenters came from over 15 overseas countries. ICCX is the initiative of CPI Worldwide, one of three international concrete-related trade journals published by ad-media GmbH in Germany. PRECAST’s editor, David Beer, took the opportunity of meeting with and interviewing three senior CPI executives at ICCX. They were: the editor in chief, Dr Holger Karutz; the publisher, Gerhard Klöckner; and CPI’s southern African editor, Dr HansDieter Beushausen, who is based at the University of Cape Town.
Besides the status of hosting an internationally prestigious event and introducing the local construction industry to a new set of influential and affluent professionals, staging ICCX in South Africa means that many more local engineers, architects, contractors and producers have had an opportunity of exposure to the collective wisdom and experience of the global construction industry than would otherwise have been the case. ICCX conferences are held in different parts of the world. For instance, the first Russian ICCX, ICCX St. Petersburg, was held in 2005. Russia, like South Africa, is also undergoing a construction boom. “We started with 45 exhibitors in St Petersburg and this grew to 55 in 2006 and 95 in December last year,” said
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 33
Dr Karutz, “and this December will see 120 companies exhibiting in St Petersburg. Berlin was another venue and in March next year ICCX will be held in Sydney. Staged in 2006, the Berlin conference was a huge success attracting 1,100 visitors, most of them from foreign countries. We had good turnouts at Cape
The major aim of the conference therefore is to expose local concrete manufacturers, architects and engineers to the huge advances in concrete and precast concrete technology.
Town and Sun City and it seems more than likely that another conference will take
South Africa last year by Lafarge. We are
“Precast concrete technology is not
place in South Africa during the second
even further behind in the application of
taught at South African universities and
half of next year.”
precast concrete technology.
there is a huge need in this country for
Dr Beushausen responded to a ques-
“Forty years ago precast concrete
precast framed structures. It will certain-
tion as to how much of the technology,
was used in South Africa for large frame
ly help in addressing the housing shortage
both through papers delivered and the
structures and then it was dropped. By
and will provide less expensive and quicker
exhibition was applicable to South Africa.
way of contrast in countries such as the
methods of erecting structures.
Having been based in South Africa for the
US, Italy and Sweden, precast technology
“For example, in Europe and America
past nine years, where, through UCT he
plays an important role in housing and
parking garages can be built to five star
has been involved in the concrete and more
other structures. South African engi-
designs within six months. T hey ar e
especially the precast concrete industry,
neers tend to be more conservative and
aesthetically pleasing, economical to
Dr Beushausen was more than qualified
like to convince themselves that a new
construct and durable. By contrast a
to comment.
technology will work before they use it.
parking garage on Cape Town’s water front
“Much of the technology on show at
Many of the technologies on show at Sun
has been in the making for the past two
ICCX, especially precast concrete, is ap-
City are new to South Africa, for example
years and we have no doubt it is going to
plicable to South Africa although some of it
self-cleaning concrete, but seeing them
be considerably more expensive than a
is not being used to its full potential owing
exhibited and being discussed in an inter-
precast equivalent would have been,” said
mainly to the mindset of some engineers
national forum may well act as a catalyst
Beushausen.
and architects who perhaps don’t fully
to their introduction here.”
Dr Karutz commented that ICCX is
appreciate its benefits. The major aim
He commented further that South
mainly dedicated to concrete producers
of the conference therefore is to expose
Af rica could benef it immensely f r om
but that a pre-conference one-day course
local concrete manufacturers, architects
precast framed structures for houses
had been held for architects and engineers
and engineers to the huge advances in
and parking garages.
at Sun City.
concrete and precast concrete technology and it was with this in mind that we tried to make the conference as interesting as possible to the local industry. We collaborated closely with the Cement and Concrete Institute (C&CI) and the Concrete Society of Southern Africa in choosing topics which would be of interest to a local audience. “Having said that there are some areas, for instance, concrete durability, where South Africa leads the world, but in general terms we tend to lag behind the rest of the world in the application of new concrete technology by about five or six years. For example, self-compacting concrete was introduced to Europe five years ago and it was only introduced to
(Above left): As this pictures clearly demonstrates, ICCX Sun City was very well attended. (Right): The CMA exhibition stand at ICCX Sun City. The CMA was a co-sponsor of ICCX
34 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
“It didn’t make sense to run a combined
if engineers are reluctant to specify them.
technology. It first appeared at ICCX /
exhibition for producers on the one hand
Therefore engineers, architects and pro-
Berlin and a second version which
and engineers and architects on the
ducers need to get together and discuss
addresses sustainability, has just been
other. Producers essentially want to view
the possibilities,” he said.
published. The first book has been a best
machinery whereas the professionals are
Dr Karutz observed that precast con-
seller and has been translated into several
interested in processes and systems. The
crete has made huge advances during the
languages. Both books can be viewed on
course was run in conjunction with Federale
past 10 years.
the web via the British Precast Associa-
Internationale du Beton (FIB) and focused
“One of the great advantages of precast
on precast concrete framed structures.
concrete is that it makes quality control a
It was attended by 75 delegates most of
much easier process. For example, modern
Ad-media publishes three journals: the
whom comprised engineers and architects
production plants are producing precast
CPI journal which is published bi-monthly
although five delegates from local precast
panelling up to 10 metres to accuracies of
and is aimed at concrete producers; AI
manufacturing companies also attended. A
1mm. Because it is made under conditions
Aggregates International deals with the
similar course was run at ICCX in Cape Town
which are more easy to control precast
quarrying, processing and transportation
where 100 delegates participated. Despite
concrete is generally of a higher quality and
of raw materials for the construction
tion on www.britishprecast.org,” noted Dr Karutz.
being a mature technology in the developed world, precast frame structures are new to South Africa and there is considerable interest in the technology. Our intention is for people who attend these courses to help grow the
industry; and an architectural
One of the great advantages of precast concrete is that it makes quality control a much easier process.
demand for precast concrete.
j o u r n a l; t h e l a t t e r a i m s a t gener ating new ideas in the uses of concrete. This is the only architectural journal which specialises in concrete. CPI is translated into eight different languages and 30 000
“Another technology with relevance for
is more durable than its insitu counterpart.
South Africa is high performance concrete
Precast structures should last longer and
and a paper was devoted to it at the con-
require less maintenance.
copies are circulated worldwide. In closing Dr Karutz and his colleagues noted that South Africa’s ICCX events
ference. It is still new to this country and
“One of yesterday’s speakers, Arnold
had been a resounding success, both in
companies are learning how to mix it and
van Acker, spoke about a 37 storey sky-
exposing local professionals to the exciting
how the mixing affects performance.
scraper in Brussels which was originally
potential of modern concrete technology
“South Africa only has a handful of
designed in steel but which was finally built
and by demonstrating the growth potential
large precast manufacturers and there
as a 40 storey building using precast
of the South African construction industry
is huge potential for the growth of the
concrete. Moerover, it was built three
to foreign companies.
existing range of precast products and
months quicker than the steel design would
the introduction of new technologies. This
have taken.
cannot be done in a haphazard fashion and
“Anyone interested in the benefits of
the industry must work together on this.
precast concrete should get hold of a copy
There is no point in building a new factory to
of Martin Clarke’s ‘Little Book of Concrete’
manufacture precast beams and columns
which lists 100 advantages of using the
P
(Above): CPI’s Dr Holger Karutz (left), Dr Hans-Dieter Beushausen and Gerhard Klöckner seen here during an interview at the ICCX Sun City conference with PRECAST’s editor, David Beer.
MAPAI
36 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
The use of precast concrete on the Gautrain rapid rail link This article is an edited extract of a paper covering the role of precast concrete elements on the Gautrain Rapid Rail Link project. The paper was co-authored by Ian Thoms, CEO of the Bombela Consortium, and Oliver Gerstmann, a civil construction engineer working on the project, and delivered by Thoms at the ICCX Conference in February. The paper covered the tunnel segments used between Rosebank Station and Shaft E2, viaduct segments and M-beam segments. The focus here is exclusively on the tunnel segments. The viaduct segments and M-beam segments could be covered in later issues.
11km Gautrain tunnel is being bored with an earth pressure balanced tunnel boring machine (EPB TBM) (Figure 2). This tunnel will connect Rosebank Station with Shaft E2, close to The Wilds, approximately two thirds of the way between Rosebank and Park Stations. This portion of the tunnel is being lined with precast concrete segments, installed within the protection of the tail shield of the TBM. The inner tunnel diameter is
The total volume of concrete needed for the
of construction, environmental friendliness,
5.860m, the outer covers 6.460m, and the
Gautrain Project is 750,000m3, of which
quality assurance and enhanced durability
segmental lining itself measures 300mm.
some 105,000m 3 will take the form of
are particularly pertinent.
precast elements. The benefits of precast
Due to exceptionally challenging soil
concrete are well recognised and in the
conditions, a high water table and shallow
context of Gautrain, cost, efficiency, speed
cover, a three kilometer section of the
(Top): Southern Pipeline Contractors ring segment production facility where mould covers have been opened to allow for surface finishing and the application of an approved curing compound.
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 37
All normal ring sections are identical and are 1.50m long, as measured along the axis of the tunnel. Excavation takes place at an average rate of 10m per day, i.e. seven rings. Each ring section consists of six segments, namely: • Three standard segments (S1, S2, S3) • Two counter-key segments (S4, S5) and • One key segment (S6). To accommodate curves in the tunnel, both horizontal and vertical, the ring segments are tapered and vary in length. Segmental length, as measured along the tunnel axis, varies between 1.490m for key segments and 1.510m for standard segments, S1, which are situated directly opposite each other. T his allows the segmented rings to follow precisely any curvature made by the tunnel within a theoretical radius of 750m, and is achieved
conditions and by live loads during operation
by rotating the rings in accordance with
must be made. Since much of the tunnel is
the geometry of the tunnel.
located beneath the groundwater table, a
To ensure that the tunnel lining is
stringent quality control system is being
water tight, a compressive gasket is
implemented to ensure that the completed
installed around the entire perimeter of
tunnel lining is watertight.
each segment, in a specially formed groove. The segments are installed using a vacuum
THE FACTORY
lifting device situated in the tail of the TBM
The precast concrete segments are being
and temporary bolts are used to stabilise
manufactured by CMA member company,
the newly installed segments against
Southern Pipeline Contractors (SPC).
the previously erected ring section. The
Concrete is produced at SPC’s batching
segments incorporate box-outs and built-in
plant which has a production capacity of
plastic sockets to facilitate the bolting.
18 m3 per hour. Forty two sets of segment
The space between the extrados of
formwork (constituting seven rings with
the ring and the rock face is injected
six segments each) have been supplied by
with mortar, thereby bonding the ring
the French tunnel engineering group CBE,
to the rock face. This limits settlement
a world leader in the highly specialised
and ensures an even load distribution on
market of steel moulds for tunnel concrete
the ring.
segments. Each mould is equipped with pneumatic vibrators and can produce
DESIGN CRITERIA
concrete segments to the very tight
The segment reinforcement design is based
tolerances of +/-1.0mm. The dimensional
on maximum ring loads, allowing the use of
tolerances of the moulds themselves are
identical rings throughout the full length
+/- 0.3mm and these are checked regularly
of the tunnel. The reinforcement design is
with appropriate templates.
based on two loading requirements, the first occurring during the construction phase, catering for loading during manufacture
(Top):??????
to the final placement of segments. The
(Left from top to bottom): The earth pressure balanced tunnel boring machine (EPB TBM) which is being used for boring a tunnel between Rosebank Station and Shaft E2, close to The Wilds, approximately two thirds of the way between Rosebank and Park Stations; the entrance to the Gautrain tunnel at Rosbank Station. Oliver Gerstmann, a civil construction engineer who works on the project, stands in the foreground]; a ring segment section comes off the production line at Southern Pipeline Contractors.
loading is also designed to handle the forces (4000t) exerted by the thrust jacks on the ring wall as the TBM advances. The second load scenario takes place during the permanent phase, when allowance for all loads created by the geological ground
38 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
are moved to the next production station where gasket fixing takes place.However, bef ore gaskets and guiding rods are placed, the purpose formed rebates are dusted and glue is applied to them using an airless spray gun. Guiding rods are then fixed to each segment so that they mate with the corresponding receiving recesses of the adjacent segment, thus assisting the accurate placement of ring segments inside the tunnel. Once in place, pressure is applied to the neoprene gaskets, so that proper bonding is achieved. Thereafter a curing compound is applied to the exposed concrete surface before a further quality contr ol check is under taken. T he production cycle is designed f or a production output of one segment (Top right): A completed section of the tunnel between Rosebank Station and shaft E2, in which the individual segments which make up the tunnel lining can be clearly seen. (Right): A segment section is manoeuvred into position inside the TBM by a segment feeder shortly before it is vacuum lifted and placed into position.
compound to the extrados. To prevent
every 10 minutes, thereby achieving 42
dehydration of the fresh concrete the
segments per working day.
mould is covered with a tarpaulin (Figure 5) for 24 hours after casting, and, provided
MATERIALS
that an early-age strength of 15MPa has
The concrete mix consists of cement
been reached, de-moulding of segments
CEM I 42.5N (350kg/m³), blast furnace
can then take place.
slag (100kg/ m³), fly ash (100kg/ m³),
The segments are then transported
aggregates (19mm max size), water and
The production cycle commences with the
to a temporary storage area for quality
plasticiser. Workability calls for 60mm
preparation of the moulds, including their
checking. This includes an inspection of
slump concrete and the maximum water/
cleaning, assembly and the application of
the gasket recess, minimum cover of
cement ratio is set at 0.45. Each segment
a releasing agent (Figure 3). Concrete is
reinforcement, extrados surface finishing,
includes 95kg of steel rebar per m³ which
poured into the moulds, and to prevent
and the finishing of arises. Should it be
is accurately assembled with the help of
segregation, each mould is vibrated for
necessary, permissible concrete repairs
specialised jigs.
no longer than 300 seconds. Fif teen
are carried out, according to approved
The minimum concrete cover to the
minutes af ter the concrete has been
segment repair methods. Moreover, at this
reinforcement is 30mm. In order to achieve
poured and compacted, the mould covers
stage each segment receives an individual
the production of one segment per mould
are opened to allow for surface finishing
identification mark. They are then rotated
per 24 hour cycle the segments require
and the application of an approved curing
180° so that the intrados face up, and
an early-age strength of at least 15MPa
PRODUCTION CYCLE
after 20 hours and they should attain
is comprised of 1.585m³ of concrete
rail wagons. They are then forwarded to
a compressive cube strength (150mm x
weighing 4.1t (concrete density 2.55t/m³),
the point of installation on a segment
150mm) of at least 50MPa after 28 days.
and one key element consists of 0.787m3
feeder and installed by the TBM’s vacuum
Before they are finally installed in the
of concrete weighing 2.0t.
segment erector.
rating of 55MPa. To ensure this, three
STORAGE / TRANSPORT / INSTALLATION
CHALLENGES / SOLUTIONS
test cubes are cast for each batch of
Four thousand segments can be stored
A huge advantage in the production of
segments and tested after 56 days.
at SPC’s factory at any one time and 50
the TBM segments has been the civil
rings (300 segments) can be stored on site
contractor’s prudent selection of an
QUANTITIES
next to the tunnel portal. The segments
established precast factory, run by an
A total of 12,000 segments, consisting
are transported from the precast factory
ex per ienced management team w i th
of 17,420m³ of concrete and 1,437t of
to the tunnel site on special road trailers
significant T BM segment experience.
reinforcement steel are being used to line
(one ring of six segments per trailer). From
The greatest challenges have related to
the three kilometer tunnel. The reinforced
the site storage area the segments are
developing the necessary standards of
concrete volume of one ring is 8.71m³.
lowered into the shaft by a tower crane
workmanship and quality assurance to
One standard or counter key segment
and transported in pairs to the TBM on
match the specification requirements.
tunnel, segments must attain a strength
This has been successfully achieved by
The greatest challenges have related to developing the necessary standards of workmanship and quality assurance to match the specification requirements.
ECHO GROUP
breaking down the production cycle into manageable elements under the control of designated supervisors, and implementing strict quality control procedures at each stage in the process. The resultant quality of the product is self-evident.
P
40 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Marley roofing system used in a sustainable and integrated housing development Marley Roofing’s EKONOROOF STEEL system is being used for the roofing of close on 3 000 houses at Olievenhoutbos Ext 36, an integrated housing development off the R55 north of Sandton. When completed at the end of 2008, some 1 410 000 Marley Double Roman Plus concrete roof tiles in a variety of through-colours will have been installed. An ABSA Development Company (DevCo) development, the Olievenhoutbos housing project was undertaken in conjunction with the City of Tshwane and the National Department of Housing. Jimmy Gif ford, Marley’s regional sales manager, says Marley’s Ekonoroof system was chosen for the project because it is ideally suited to large housing developments. “Increasing use is being made of concrete roof tiles for entry-level housing projects. Research conducted by the CMA has shown that concrete tiles are the most costeffective material on roofs built with trusses. Moreover, they offer other advantages such as excellent aesthetics, low maintenance and good insulation properties.” Gifford notes further that most roofing materials start deteriorating as soon as they are exposed to the weather.
subsidiary of MiTek in the USA and has been operating in South Africa since 1993, initially to produce metal connectors for timber roof trusses and since 2000, to manufacture complete steel trusses for various sectors of the roofing market, which besides housing, also includes commercial and industrial bulldozers. MiTek’s ULTRA-SPAN system has been successfully exported to other parts of (Above): MiTek’s One of the free-standing houses at Olievenhoutbos Ext 36, where some 1 410 000 Marley Double Roman Plus concrete roof tiles were used for the roofing of close on 3 000 houses.
Africa. Three licensees operate in Nigeria and the system has also done well in Angola and Botswana. It was used to roof some 900 houses at Angola’s Nova Vida housing
“By contrast, concrete grows stronger
complex in 2001 and a shopping centre in
with age and exposure to the elements.
Kwaneng near Gaborone is currently being
This important factor contributes toward
roofed using Mitek trusses.
making quality concrete roof tiles the most
Of the 2 981 houses which make up the
successful, cost-effective long term roofing
Olievenhoutbos Breaking New Ground (BNG)
material for affordable housing.”
units (former RDP houses), 544 comprise
EKONOROOF STEEL is a custom designed
duplex (row-house) units of 44m² built in
roofing solution which incorporates the
blocks of three or four units per block. In
MiTek ULTRA-SPAN truss system.
addition 1 417 semi-detached and 1 020
Richard Bailey, general manager of MiTek
free-standing houses are being erected,
ULTRA-SPAN, says that the system uses a
with an average size of 38 m 2 and 36
special galvanised steel, and was developed
m² respectively. The units have individual
jointly with Marley.
service connections and pine floors are
“These trusses have excellent strength
being installed on the double-storey units.
-to-weight properties and are quickly
Bigen Africa Ser vices, Road Crete
assembled and erected. They were delivered
A f rica and L e f ika Constr uction wer e
on site as knockdown kits and were then
responsible for infrastructure installation,
assembled in accordance with MiTek and
and Bigen Africa in conjunction with HAD
its specifications, by unemployed and
Services, designed and project-managed
unskilled people.
the construction of the houses. Sea Kay
“Four roof assembly teams were trained from scratch by Marley in all aspects of
Engineering Services is the main topstructure contractor.
roof construction. MiTek did the training
Concrete bricks were the other major
on the assembly of the trusses. Some of
precast element on this project. Sedibeng’s
the workers became so skilled that they
Maxi brick measuring 290 x 100 x 140mm
have been able to find similar employment
and produced to a strength of 10MPa is
on other construction sites.
being used. After brick laying, the walls
“Each team took 25 minutes to assemble
were bag-washed and painted.
P
eight trusses using jigs and power tools and then it took them a further one-and-a-half hours to complete a roof. This entailed erecting the trusses, under-tile membrane, battens and bracing, as well as laying the tiles,” he said. MiTek South Africa is a wholly-owned
(Above left): MiTek’s ULTRA-SPAN galvanised steel trusses shortly before being lifted into position at one of the houses in Olievenhoutbos Ext 36. (Left): A row of free-standing houses at Olievenhoutbos Ext 36, where some 1 410 000 Marley Double Roman Plus concrete roof tiles were used for the roofing of close on 3 000 houses.
Some of the workers became so skilled that they have been able to find similar employment on other construction sites.
42 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Massive retaining wall requirement at fnb/wesbank development The newly completed FNB/Wesbank administrative centre in Fairland, Johannesburg, is a development which has generated considerable interest among construction professionals and members of the public alike, owing primarily to some highly innovative architecture used in its design by Kim Fairbairn of Continuum Architects (Pty) Ltd. Having been built on a site with a considerable and varied slope, it is a development which required extensive retaining wall support. A total of eight retaining walls were built, some of which reached heights of 7.5m. These cover an area of some 3 000m² and used close on 30 000 concrete retaining blocks (CRB) in their construction. CRB walls are more cost-effective than conventional reinforced concrete walls and are considerably more attractive, facilitating as they do varying shapes and contours as well as the growth of plants in the soil-filled blocks. All the walls were built by Kalode Construction using INFRASET’s Terrace Block retaining system, the one exception being an internal wall in the Basement 3, which was built using Concor Technicrete’s Envirowall block system. This wall comprised a geogrid reinforced fill structure built at 85º and the Envirowall block is best suited to this type of application. The walls were built in two phases. Phase 1, which comprised the Basement 3 wall and the fire escape structured fill wall on the north side of the project, was designed by John Joubert of
development. A pure gravity structure, the wall is 60 metres end-
Foundation and Slope Stability Engineering, and Phase 2, which
to-end and reaches three metres at its highest point.
consisted of remainder of the walls, was designed by Herman Pietersen of Herman Pietersen and Associates.
Further evidence that retaining walls play a crucial role at this site becomes apparent at the gatehouse where 5 000 CRBs
Anyone visiting the site for the first time will be immediately
were used to create an attractive 80 metre wall. Once plants
confronted by a retaining wall at the Willson Street entrance.
and flowers are established on this section of wall it will form an
Although not part of the FNB/Wesbank development per se, it was
extremely attractive feature. The wall itself entailed a standard
also constructed by Kalode Construction on behalf of Brian Wescott
design and installation. It rests on a concrete strip footing 200mm
Construction. Completed in 2006, the wall was built on the southern
deep by 600mm wide, tops 4.5m at its apex, and for the most part,
slope of the feeder road which serves both the FNB/Wesbank
slopes at angle of 70º. Blasting was necessary on parts of this
development and Worldwear Shopping Centre adjacent to the FNB
section and the exposed rock face was covered with CRB blocks.
(Top right): This 70m x seven metre high retaining wall, built with INFRASET Terrace Blocks is situated on the northern side of the FNB/Wesbank development and supports a fire escape.
a wall was built to support a fire escape on the north-west side of
(Right): A 140m x 7.5m high retaining wall section was built with INFRASET Terrace Blocks and is situated on the southern side of the FNB/Wesbank development.
One of the more challenging CRB projects at the FNB site was the development. It is 70m long, seven metres high and is built at an angle of 70º. The fill in this wall is well compacted and reinforced with high strength polyester geogrids supplied by Kaytech. The fire
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 43
escape sits directly on the structural fills and applies loadings on
A composite wall, it was constructed with a double skin up to a
these fills of 150kPa.
height of four metres and a standard geogrid reinforced fill was
The wall built with Concor’s Envirowall blocks is a vertical
used above that to maintain the weight.
structure and is situated in the basement which houses the
Another wall section, the south western pod, was built around
building’s fire fighting equipment. Approximately 14 000 blocks
a staircase. It is also a composite structure in which cement
were used on this wall and Kalode were responsible for all the fills
stabilised soils and geogrids as well as plain geogrid reinforced fills
and the stabilising.
and terraced stepbacks were used to accommodate the staircase
This wall was offered as an alternative to the originally proposed
landings and to break the stark lines of a high CRB wall situated in
retaining wall as it was much more cost effective, by approximately
confined surroundings. It is 125m long, varies between three and
40%. Just on 100m long and reaching a height of 6.8m, the top half
eight metres in height, and has a 70º slope.
of the structure was reinforced with tensioned polyester geogrids
All structures were built with adequate subsoil drainage consisting
which extend into the backfill. The bottom 2.5m section of the wall
of clean stone wrapped in horizontally-laid Kaytape A2 . Wick drains
was constructed out of 5% cement stabalised fill reinforced with
250mm wide were laid on the face of the exposed embankment and
tensioned polyester grids.
these act as sub-soil cut-off and collector drains.
P
Kalode Construction managing director, Jan Pienaar, says Envirowall blocks were used on this wall as they are ideal for vertical structures that are heavily loaded . The bottom two metre section of the wall is a cement stabalised soil reinforced with stretched geogrids from Kaytech. The top 4.5m is a conventional stretched soil reinforced structure with the blocks acting more as a facing than a structural element. On the south eastern and south western section of the building
3 C&CI corporate ad FINAL 8/8/06 11:05 AM Page 1
a sunken wall 6.5m high and 93m long was built at a slope of 70º.
This wall was offered as an alternative to the originally proposed retaining wall as it was much more cost effective, by approximately 40%. C
M
Y
CM
MY
CY CMY
K
When it comes to concrete…
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44 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008
Membership June 2008 Company Name
Phone No
FAX
PRODUCT
ARW Concrete Holdings
011 460 0921
011 460 0924
R
A Fick Cement Works
022 913 1921
022 913 2370
M
Bafokeng Concor Technicrete
014 538 0818
014 538 0806
MPRT
Bamburi Special Products (Kenya)
00254 282 4478/9
n/a
P
*Baybrick
035 791 1238
035 791 1235
P
Boland Concrete
021 875 5365/021
n/a
M
Bosun Brick Midrand
011 310 1176
011 310 1178
P
Brick & Concrete Industries (Namibia)
00264 61 321 3009
00264 61 321 3041/2
MP
*Brickcast Industries
031 507 5525
031 507 7094
P
Brickbuild T/A Panda (Botswana)
00267 244 2106
00267 244 2110
MP
*Brikor
011 316 1200
011 316 1380
T
*Cape Brick
021 511 2006
021 511 2172
MPR
*Cast Industries
011 316 2375
011 316 2394
P
C.E.L. Paving Products
021 905 5998
021 905 5988
P
*Columbia DBL
021 905 1665
021 905 4049
MPR
Concor Technicrete
011 495 2200
011 495 2489
MPRT
*Concor Technicrete (Mpumalanga)
013 758 1203
n/a
MPRT
*Concor Technicrete (Mpumalanga)
017 689 2100
n/a
MPRT
*Concor Technicrete (Mpumalanga)
013 696 1153
n/a
MPRT
*Concor Technicrete (Free State)
057 391 4200
n/a
MPRT
*Concor Technicrete (Limpopo)
015 293 8083
n/a
MPRT
Concor Technicrete (Gauteng)
011 203 7700
n/a
MPRT
*Concor Technicrete (North West)
018 484 6234
n/a
MPRT
*Coastal Concor Technicrete
041 372 2230
041 372 2200
MPRT
*Concrete Units
021 386 1923
011 386 2514
Pi
*Consteen
012 374 9300
012 374 9301
P
*Corobrik
031 560 3911
031 560 3180
PR
Deranco Blocks
041 463 3338
041 463 2602
MR
Deranco Paving
041 933 2755
041 933 5910
MR
Deranco Precast
041 463 3338
041 933 2602
S
*Eagle Roof Tiles
044 874 0290
044 874 0282
T
Ecco-Euro Paving
011 786 3109
011 786 3161
P
Echo Floors
011 957 2033
086 667 2037
S
Echo Prestress
087 940 2060
086 514 7342
S
Echo Prestress KZN
031 569 6950
031 569 6974
S
Fastfloor Botswana
011 393 4655
011 393 4651
S
Fort Concrete
00263 448 6620
n/a
Pi
Inca Concrete Products
021 904 1620
021 904 6115
MP
*Inca Masonry Products
043 745 1215
043 745 1501
MPRT
PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 45
*Infraset
011 876 5500
011 872 1713
Pi
*Infraset
012 652 0000
012 652 0132
MPR
*Infraset
031 569 6900
031 569 6903
PR
Kwena Brickforce (Botswana)
00267 392 2850
00267 392 2840
P
Klapmuts Concrete & Cape Retaining
021 875 5151 5665
021 875 5151 5665
R
*Kopano/Altocrete
016 363 0340
016 363 0714
P
*KuluCrete South Coast
039 685 4165
039) 685 5166
MPR
Kwena Rocla
00267 392 2850
00267 392 2840
P
Lategans Cement Works
021 873 1154
021 873 4910
M
*Marley Roofing
011 316 2121
011 316 1498
T
*Marley Roofing
011 933 3351
n/a
T
*Marley Roofing
011 944 4155
n/a
T
Mobicast Mossel Bay
044 874 2268
044 873 3114
P
*Mimosa
012 374 9300
n/a
P
*MVA
012 386 0050
012 386 0073
P
*Monier South Africa (H.O.)
016 430 8000
016 430 8068
T
*Monier South Africa
011 914 4580
011 866 2462
T
*Monier South Africa (Free State)
051 432 5089
n/a
T
*Monier South Africa (North West)
012 250 2218
n/a
T
*Monier South Africa (Cape Town)
021 534 1441
021 534 7851
T
*Monier South Africa (DBN)
031 565 1312
031 565 2911
T
*Monier South Africa (ELN)
043 743 2191
n/a
T
*Monier South Africa (George)
044 878 1325
n/a
T
*Monier South Africa (PE)
041 463 2629
n/a
T
*Neat Contech
046 624 3377
n/a
MPRS
PRO Brick & Block
021 905 3362
021 905 4889
M
ReMaCon Products
011 393 5504
011 393 5502
R
*Rocla
011 670 7600
011 472 2141
Pi
*Salberg Concrete Products
011 357 7600
011 357 7635
Pi
*Southern Pipeline Contractors
011 914 8500
011 914 4524
Pi
Stabilan
051 434 2218
051 435 3925
S
*Stanger Brick & Tile
032 457 0237
n/a
MP
Shukuma Flooring System
041 372 1933
041 372 1944
S
Stone Age Concepts
012 802 1496
086 616 3734
P
Topfloor
021 552 3147
021 552 6892
S
*Van Dyk Steengroewe
022 713 1244
022 713 1500
M
Vanstone Precast
012 541 2056
012 541 1808
PR
*Vibro Bricks Pretoria
012 374 9300
012 374 9301
P
*Watson Concrete
011 740 0910
011 744 4472
MP
*Western Granite Bricks
021 904 1620
021 904 6114
M
White River Cement & Bricks
013 750 1271
013 750 0822
MPR
*Companies, which hold the SABS Mark P = Paving
M = Masonry
R = Retaining Blocks
T = Roof Tiles
S = Floor Slabs
Pi = Pipes
PRECAST VOL 1 JUNE 2007 25
PRECAST VOLUME ONE ISSUE 3 • JUNE 2008
• Resevoir built with precast hollow-core slabs • The benefits and design of permeable paving • The use of precast concrete on Gautrain