Precast Magazine June 2006

Page 1

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.


ADVERT


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…

talk to C&CI

Our team of technical, information and education specialists is on hand to answer your questions and train your staff

Let our expertise work for you!

2193

Tel (011) 315 0300 - Fax (011) 315 0584 E-mail info@cnci.org.za - Website www.cnci.org.za


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


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