CMA Precast June 2008

Page 1

PRECAST VOLUME TWO ISSUE 1 • JUNE 2008

• Reservoir built with precast hollow-core slabs • The benefits and design of permeable paving • The use of precast segments on Gautrain



contents 36

The use of precast concrete tunnel segments on Gautrain

40

Marley roofing system used on a sustainable and integrated housing development

Gill Owens retires

42

Massive retaining wall project at FNB/Wesbank development

7

Gautrain sleeper delivery on track

44 CMA Membership list

8

Building a pool between a rock and a hard place

8

Sikaquick 2500 quick fix

9

CMA publishes leaflet on D.I.Y. CRB wall construction

2

Message from the president

4

Obituary – Nick Doulgeris

6

Strong demand for Infraset’s roof tiles

6

The storage yard at Southern Pipeline Contractors (SPC), where precast concrete ring segments await delivery to the Rosebank tunnel after manufacture at SPC. Due to exceptionally challenging soil conditions, a high water table and shallow cover, a three kilometer section of the 11km Gautrain tunnel between Rosebank and Shaft E2 near The Wilds, is being lined with these segments. They are being installed within the tail shield of the tunnel boring machine (EPB TBM).

PRECAST VOLUME TWO ISSUE 1 • JUNE 2008

Mapei launches SADC initiative 10 at ICCX conference

12 CMA introduces block masons’ site manual Concor Technicrete permeable pavers

12 used in Durban

Chryso SA establishes production

13 facility in KZN

• Reservoir built with precast hollow-core slabs • The benefits and design of permeable paving • The use of precast segments on Gautrain

The segments are 300mm thick, and once in place, the inner tunnel diameter measures 5.860m and the outer diameter 6.460m. All normal ring sections are identical and are 1.50m long, as measured along the axis of the tunnel.

PRECAST is the official journal of the Concrete Manufacturers Association (CMA). Block D, Lone Creek, Waterfall Office Park, Bekker Road, Midrand.

Cellulose fibre reinforced cement fails 14 University of Pretoria strength tests as a gravity piping material

18

Water reservoir built with hollow core precast concrete slabs – a South African first The benefits and design of permeable

20 interlocking concrete paving 28

The Virginia Sewer Experiment – contributing to sewer design

32

ICCX offers real advancement potential to local construction industry

PO Box 168 Halfway House 1685 Tel: +27 11 805 6742, Fax: +27 86 524 9216 e-mail: main.cma@gmail.com

website: www.cma.org.za

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

It was, and to an extent still is, what our design engineers are taught 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 storm-water data. The second is an extension of the first, having

Message from the president The days of indiscriminant resource exploitation are numbered. The only ‘commodity’ we appear not to be short of is people. It is now common cause that everything we do has an effect on our fragile environment. Understanding the concept, however, is only the first step; the nettle will have to be grasped if meaningful progress in sustainable life-styles is to be made. This will entail measuring all our activities in terms of their environmental impact or life-cost. In other words man must become adept at eco-costing, so that the environmental as well as financial costs are weighed up in our day-to-day activities. Those of us in the construction industry will have to establish the eco-cost of materials and building processes, and once our structures are completed, the eco-running expenses. Already one finds that, if correctly designed, a new building can achieve reductions of up to 70% in the consumption of power, water and utilities, and could be eco-rated on those savings. Obviously the use of recycled materials is to be encouraged and, in our last issue, we covered a Western Cape-based CMA member who

been culled from a paper delivered by Dr Shackel at this year’s ICCX conference. It examines some of 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 an interview with ICCX’s international conference organizers. Non-ICCX related material includes: an update on the Virginia Experimental Sewer, the only undertaking of this kind in the world; a comparative piece in which the properties and performance of fibre reinforced piping (FRC) and concrete pipes are examined; an article on the extensive use of concrete reinforced block (CRB) walling at the futuristic Wesbank development in Fairland, Johannesburg; the use of concrete roof tiles on a major low-cost housing development in Gauteng; and, in another first for industry, an article covering the use of hollow-core precast concrete slabs in the construction of a reservoir. Finally, as this issue goes to press, all entries for the CMA’s Awards for Excellence competition will have been submitted. The judging is taking place in June and the presentation of the national awards is to be held at The Theatre on The Track on October 11. I’d 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.

Garth Gregory, CMA President

P



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.

Dr 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, especially off-road scramblers. He

Portland Cement Institute (now Cement

was very involved with the sport, helping

and Concrete Institute) where he did much

young riders tune and maintain their

of the work for which he is remembered.

machines, and was instrumental in the

Lane explained that Nick grew up in

establishment of a scrambler track near

Zimbabwe and worked for the Ministry of

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

team. “Nick was a man who always gave

moving tribute at the funeral when he

120%. He was technically very sound and

described how, along with teaching him

in his quiet way, was forthright in giving his

about bikes, Nick taught him about life,

opinion. He would not hesitate to disagree

honesty and decency. “On one occasion I

if he believed that his view was correct –

had bought some spares for my bike and

which it often was.”

some time later I discovered that I had

A t P C I h e b e c am e k n o w n f o r h i s

under-paid the dealer. Nick insisted that I

dedication and diligence, for his willingness

go back and pay the difference. This was the

to go the extra mile, even if it involved

kind of person he was – absolutely straight,

coming to work before dawn or leaving late

absolutely honest and an inspiration to who

at night, to ensure that his clients got the

knew him.”

P

right answer – and got 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 in his quiet way, was forthright in giving his opinion.


Concrete Block Paving THE LOW-MAINTENANCE ALTERNATIVE TO PAVEMENT SURFACING Rugged beauty, dependability, not to mention an extremely frugal maintenance requirement, are qualities which define concrete block paving. Covering millions of square kilometres worldwide, it is a surfacing material suited to numerous and diverse applications such as roads, industrial yards, town squares, domestic driveways, patios and paths.

In a southern African context it makes even more sense: creating jobs, transferring skills and empowering communities.

Block D, Lone Creek, Waterfall Office Park, Bekker Road, Midrand. PO Box 168 Halfway House 1685 Tel +27 11 805 6742, Fax +27 86 524 9216 e-mail: main.cma@gmail.com

website: www.cma.org.za


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 factory at Rossway, Midrand. The plant, which

experienced surprisingly buoyant demand for its new range of

is initially serving the Gauteng roofing market, is producing two

concrete roof tiles.

roofing profiles, Sunset, a bold roll tile, and Horizon, a flat shingle

Some major housing projects are already being supplied by

tile, and both types are in great demand on the local market.

INFRASET. These include: Heritage Heights in Krugersdorp where

They are manufactured in a range of five through-colours and a

100 houses are being supplied with Sunset Multi-Blend tiles;

selection 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).

P

(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 computerised in 1989, was very important

definitive reference publication, Fulton’s Concrete Technology.

P

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 .25mm.” 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.”

P

(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.


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 of 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. The lower photo shows such 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 ensure that this retaining installation provides both a practical and attractive end product.

P

(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.

P


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.

“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

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 and foundation material. Instructions are also given on laying the first course of blocks and subsequent layers.

The leaflet also lists CMA producer and contractor membership details 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.

P


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, the Czech Republic, and more

construction, and cementitious and resin

pillars, namely, specialisation, a strong

especially Russia, where the growth in

floor coatings.

international presence, and research and

demand for Mapei’s substantial product

“Our entry into the southern African

range, is believed to be the world’s highest.

market means that we have extended

“Five percent of the group’s turnover

The group currently operates through 50

our global reach. Worldwide we deliver

is spent on research and development

associate companies with 47 production

16 000 tons o f pr oduc t to 4 0 000

in cooperation with many of the world’s

facilities across 33 countries worldwide.

customers daily,” Dr Squinzi observed.

major universities and we were the first

development.

Dr Squinzi was introduced to a large

During his address Dr Squinzi announced

to introduce PCE admixtures to the global

gathering of conference delegates by Aveng

that Mapei would be building a local

market. We have also introduced new

Group CEO, Carl Grim, who spoke briefly

manufacturing facility in line with Mapei’s

products to many other countries, and

about Mapei’s joint venture with Aveng.

policy of manufacturing in the countries it

our Norwegian operation was the first to

Dr Squinzi noted that there was huge

serves. The local plant will be Mapei’s 47th,

introduce several new products in that

growth potential in the local construction

and like all its other factories, it will comply

part of Scandinavia,” said Dr Squinzi.

industry and that he wanted Mapei to

with ISO 9001 standards.

participate in and contribute to it.

Seven Mapei R&D laboratories are

“We believe in situating our factories

operated worldwide, two in Italy, and one

“We have signed a local distribution

close to our customers so that they can be

each in France, Germany, Norway, Canada

agreement with the Aveng Group and a

provided with the lowest possible costs and

and the United States. Of the group’s

comprehensive range of enhancement

the quickest possible delivery times.”

5 300 employees 12% work in R&D.

products for the construction industry is

Mapei has grown from a small family-

Mapei is also a generous patron of

already being distributed by its subsidiary,

run business f ounded in 1937 by Dr

cultural and sporting events. It sponsored

Engineered Concrete Systems (ECS).

Squinzi’s father, into a major multi-national

two social events at ICCX, a bush braai

concern. However, despite its size it is still

and the main gala dinner, and even more

controlled by the Squinzi family.

notable was its sponsorship of Italy’s

“Mapei operates on a local expertise and management system and therefore we are South African in South Africa, as

Dr Squinzi observed that the success

we are Italian in Italy. The same principle

of the group has been founded on three

national soccer team, which won the World Cup in 2006.

P



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 55

and wall pier options are

definitions and these cover all aspects of

also illustrated here.

the technical terminology covered in the

Compiled and co-edited by masonr y consultant, Günter Koch, the manual

Footings and f ounda-

preceding pages.

is aimed at both skilled and unskilled brick

tions are covered in the third section,

Koch says one of the recurring prob-

layers, providing guidance in building to

and layout and detailing in the next. The

lems in South African modular masonry

specified standards.

latter is broken down into the following

is the proper selection of mortar and

Koch says much of the detail provided

headings:

plaster aggregates, as these differ from

in the manual is based on internationally

• Corners

region to region.

accepted modular masonry standards.

• Wall dimensions

The first section illustrates block laying

“This requires local knowledge and

• Intersecting walls

e x p er i en c e in ch o o sing th e c o r 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

imposed flow restrictions on the municipal

“Many former residential areas, such as

paving blocks were used in the construction

storm-water network and had specified

this particular site, have been rezoned for

of a permeable paving surface for a 480m²

attenuated storage for the site.

commercial and industrial purposes, with the

pedestrian pr ecinct and car park on

“However, there was very little land

Kensington Boulevard, Durban North. The

available for storage of sufficient capacity,

sub-base acts as a reservoir and during

and a permeable paving alternative was

heavy rain at least 60% of run-off surface

recommended by the engineers.”

water is captured.

The benefits of this Aquaflow system

The sub-base comprises a foundation

extend well beyond the sub-base reservoir.

layer of compacted 63/10mm stone and

It also receives run-off from other parts of

above that there is a mesh lining, a 100mm

the site, entering through the side of the

layer of 20/4mm compacted stone, a geo-

reservoir and being distributed over its

fabric liner and 50mm of compacted 6mm

length via a perforated pipe.

clean stone.

Detailed environmental impact research

Tony Bezuidenhout, managing director of

w en t in t o the pr oje c t ac 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. Project manager, Wayne Jordaan of Key Projects, said the local municipality had

(Right): Kensington Boulevard, Durban North, where Concor Technicrete’s Aqua Trojan paving blocks were used for a permeable paving system.

result that there is now much more stormwater run-off.”

P


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 as 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 begun 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 operation, 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 manufacturing), 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

(Above 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) maintains FRC pipe has several other shortcomings, referred to in this article, which cast doubt as to its role as a gravity piping material, and it 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

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

at odds with some reputable information sources. 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 50MPa and the highest strength calculated for the pipes that were tested

Table 2: Strength of pipes tested wet.

dry was 41.8MPa. These results do however clearly indicate that

Sample

ID (mm)

Length (mm)

Wall (mm)

Failure load (N)

Strength (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)

Strength (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

Another concern is that SANS 819:2006 only applies to fibre

the difference between laboratory testing and actual installed

reinforced pipes of up to 1 000mm in diameter. There is no standard

conditions into account, ‘n’ values of 0.012 and of 0.013 are

for larger diameter fibre reinforced pipes.

usually specified for actual designs using both materials.

Reinforced concrete pipes have a proven life of 100+ years and

A safety factor of 1.5 is claimed for FRC pipes thereby offering

the structural performance is not influenced negatively by wet

“the specifier a safe, proven alternative which will perform under

conditions. On the contrary, concrete strengths improve in wet

high-loading conditions”.

and moist conditions.

P

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.

(Above): A typical concrete pipe installation.


18 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008

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

330mm and 330mm wide x 1 200mm

feed the surrounding high-lying area 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 create employment for

Both the reservoir and the water tower

local bricklayers. The beams and columns

are supplied by electronically controlled

could have been replaced by precast

pumps which in turn feed all the other

components 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 first.

retaining structures is all important.

CMA director, John Cairns comments

“On-site concr ete mixing r equir es a

that the Lindley reser voir project is

f ull-time super v isor to ensur e the

further evidence of the versatility of

correct consistency and this certainly

precast hollow-core slab technology.

applied 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.”

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 (left), 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 computer-based mechanistic analysis and design software programme, which intergrates with modern concepts of sustainability and water-sensitive urban design. The advantages of permeable paving include

However, it is worth noting that, as yet,

not only stormwater management, pollution

no special maintenance requirements have

contr ol and water r e-use, but o f f er

materialised. Several European installations

economic advantages by minimising the

have been in service for 15 years or longer

costs of surface drainage works, thereby

with only routine maintenance, such as

when:

reducing the demands on stormwater

car and bus parking areas at the Prater

• Stormwater and sewer systems are

sewerage, and optimising land use. Recent

Football Stadium in Vienna.

studies in the UK have shown that PICP

Typical regulations for new urban paving

yields significantly lower initial and whole-

developments may include:

of-life costs than asphalt or cast-in-

• Limits on the extent of

place concrete surfaces. Initial concerns

impermeable areas

about the long-term maintenance cost

• On-site retention of rainwater

of permeable paving due to clogging have

• Control of the discharge rate

largely been allayed through tests in

• Control of the discharged water quality

Europe, North America and Australia.

• Measures to reduce sedimentation

These tests indicate that permeable paving can achieve a service life in excess

and/or pollution, and, increasingly, • Measures for harvesting and

(Above): A close up view of the laid permeable paving stones at a new car park at the University of the Witwatersrand.

Permeable paving should be considered

close to capacity • There are limitations on the extent of impermeable cover • There is insufficient space for both vehicle use and attenuation ponds • Water quality and pollution control are primary design objectives. For these reasons, PICP provides an option especially relevant to urban roads. However, it has also been successful in heavily trafficked applications such as

of 25 years without maintenance, and more

re-using rainfall

importantly, that pollutants accumulate

To meet such requirements, best man-

mainl y in the upper 25 to 50mm o f

agement practices (BMP) include controls

DeSiGN Of PerMeaBLe PaViNG

the aggregate used to fill the joints or

for reducing or managing pollutants, proce-

Several distinct engineering requirements

drainage apertures. Where necessary,

dures for the proper disposal of waste, and

must be addressed in designing permeable

polluted material can therefore be easily

the use of flood management procedures

paving. Ideally the methodology should

and economically removed and replaced.

which assess impact on water quality.

embrace the following objectives:

container yards.


PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 21

• Flood mitigation by retention or detention (i.e. water quantity) • Water quality improvement by filtration or retention (i.e. water quality) • Water conservation by collection and re-use (i.e. water harvesting) • The ability to carry traffic

these is likely to require a different paving

integrated approach to PICP design which

thickness. Clearly, the designer must opt

can handle most generic types of paver.

for the greater thickness. Software for structural design is already available in the LOCKPAVE programme. A new

The principal design questions are: 1. What is the design life of the pavement? 2. How fast can pavement accept

programme, PERMPAVE, was commissioned

rainfall? This depends on the paver

for hydraulic design by the Concrete Masonry

type, the crossfall, the bedding and

A n o v er v i e w o f p er m e ab l e p a v ing

Association of Australia in 2006. It has been

drainage materials, and the type of

design is given in Figure 1. It shows

developed by the School of Natural and Built

base and sub-base.

that, in contrast to conventional paving,

Environments at the University of South

permeable paving involves two parallel

Australia in conjunction with the author,

This is related to the type of base and

design requirements: structural design

the developer of LOCKPAVE. Together,

sub-base, the type of subgrade and

and stormwater management. Each of

LOCKPAVE and PERMPAVE provide an

3. How fast will the pavement drain?

the position of the water table. 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.




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 programme uses the design

the pavement system, and this entails

storm approach. In time, however, it is

choosing the right cross-section and

expected to move to continuous simulation

pavement materials. Broadly three cases

as local 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

Several general methods using

management. Hitherto, most analyses of

Suitable cross-sections and design

nomogr aphs ha v e b een published t o

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.

remove infiltration.

Catchments can be large, for example,

2. Pollution control: what is the quality of

embracing entire suburbs. Critical loca-

the effluent leaving the pavement? 3. Water harvesting. How much water can be stored and re-used? S t Or M Wat e r 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 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.

tions, where local authorities regulate flows and/or water quality, are normally found some distance from PICP installations. T herefore, the critical factor is how PICPs impact on catchments beyond and dow nstr e am o f their immedia te 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 As mentioned above, the pavement thicknesses required for stormwater management normally differ from those needed to carry traffic. This means that in addition to water management, traffic flows and loadsoftware programs if municipal engineers

• Temporal zone

ing must be considered in the structural

are to adopt it.

• Average storm intensity

design. Worldwide, PICP has already been

• Antecedent condition (e.g. part-full

successfully used in projects ranging from

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

car parks to roads, ports and container yards. Accordingly, any structural design

rainfall records. Arbitrary assumptions

WAter QuAlItY, HArveStIng

procedure should be capable of handling a

about the state of storage in the pavement

aND re-USe

wide range of traffic conditions while utilis-

– for example, whether they are to be

Water quality and har vesting /r e-use

ing the full range of new materials which are

empty or half-full at the commencement

analysis can be undertaken using a simplified

available for the 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 permeable paving system • Proposed area of the permeable paving system • Impervious area not draining into the permeable paving • Pervious area not draining into 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

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

drainage system. The second is to filter

water management methods which are

and r e t ain the st or mwa t er on-si t e,

modelled in PERMPAVE.

allowing it to percolate slowly 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

permeable paving

• Soil saturated hydraulic conductivity • Drainage outlet discharge characteristics Storm data must include:

characteristics • Pollutant removal efficiency characteristics • Historical rainfall data

• 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

achieving water-sensitive urban design.

Mr) of the materials. The modulus falls with

thicknesses for PICP compared to CSP.

There is now sufficient data to allow the

any increase in saturation, yet most studies

However, as noted above, the final design

design of PICP for all types of applications

of Mr have been carried out under relatively

thickness for PICPs is determined by the

to proceed with confidence. The design

dry conditions close to optimum moisture

greater of the two thickness requirements,

engineer needs to identify retention and

content (OMC). General relationships

which is either based on stormwater

detention requirements, predict outflows

between Mr and moisture content for

management or traf fic loading. In the

to the surrounding catchment, integrate

base and sub-base materials, published

author’s experience the thickness needed

the project as a node in existing catchment

by the author in Australia, show that Mr

for water management is often greater

management procedures and software, and

values at high moisture contents may be

than tha t r e quir e d f or tr a f f ic. T his

ensure it is compatible with water quality

only 50% or 60% of those customarily

means that there is usually no economic

monitoring programme. All these factors

used in mechanistic pavement design for

disadvantage in the use of thicker PICP

are rated very important by municipal

materials meeting current base or drainage

pavers compared to conventional CBPs,

engineer s f or whom water -sensiti ve

layer specifications. Similar reductions in

because stormwater considerations often

urban design is a basic requirement.

Mr are found when using scalped granular

determine the final thickness. However,

PERMPAVE is intended to help PICP reach

base materials. In the absence of Mr

it would be unwise to assume that this

its full potential by embracing stormwater

values which have been measured at high

will always be the case, especially where

management, water quality and water

saturation levels, choosing Mr values,

heavy traffic must be carried. Accordingly,

harvesting. At the same time the software

roughly half of which are routinely adopted,

the stormwater design should always be

is designed to co-exist with the catchment

would be prudent.

accompanied by a structural analysis.

management and water quality software

The use of lower Mr values than are

that is already widely used in countries

commonly selected for the structural

cONcLUSiON

which apply the principles of sustainable

design of conventional pavements leads

P I C P is an imp o r t an t t e chni qu e f o r

urban design.

P



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). The Virginia sewer operates under very

both the binder and aggregate were

• All the protected pipes performed

aggressive conditions and is the only such

corroded whereas on the latter only

satisfactorily except where the

experiment ever to have been undertaken

the binder was affected.

coatings were damaged.

anywhere under such conditions. At the

• Concrete made with calcium aluminate

outset, predictive theory indicated that

cement (CAC) appeared to be performing

laboratory, showed little correlation

a standard concrete would corrode at

more effectively than concrete made

with the biogenic attack in the

a rate of ±6.5 mm per annum whereas

using Portland Cement (PC).

experimental sewer.

a dolomitic aggr egate concr ete, the

• Although the asbestos fibre rein-

• The pure, or mineral acid attack in the

The five-year inspection confirmed the

traditional solution for sewer pipes, would

forced (AC) pipes had corroded, the

two year findings, but the differences

corrode at a rate of ±1.3 mm per annum.

corroded material did not break off.

between the performance of the materials

This meant that the traditional solution,

Instead, it remained intact but swollen,

was now more marked. The most significant

which had pr oved e f f ec ti ve on most

owing to fibres in the pipe wall which

findings on the unprotected pipes were:

sewers, would not be suitable for a sewer

held the corroded material together.

• The PC/SIL concrete was performing

with a life expectancy of at least 40 to 50 years under such aggressive conditions.

as predicted • The PC/DOL concrete was performing

Therefore, the project specification called

better than the PC/SIL concrete

for either a lined concrete or a coated

but not quite as well as had been

fibre cement pipe. A by-pass section was

predicted. This was due to varying

also constructed so that effluent could be

rates of corrosion between the

diverted around the experimental section

aggregate on the one hand and the

during inspections.

binder on the other. Some aggregate fallout was also observed

rOUtiNe iNSPectiONS tHe FIrSt DeCADe Regular inspections, during which material losses were measured and gas readings

• The CAC pipes were performing better than the other unprotected pipes and certainly much better than predicted • The unprotected AC pipes were

taken, took place. Initially sections of the

performing close to what had been

pipe were also subjected to pure acid tests

predicted providing the depth of the

in the BOUTEK laboratory at the CSIR in

soft corroded products was deducted

an endeavor to obtain correlation between

from the wall thickness.

laboratory testing and site conditions. After two years some clear trends could be identified:

These findings led a pipe supplier and a CAC supplier to investigate the feasibility of making pipes with a CAC/DOL concrete.

• The difference between the performance of concretes made with dolomitic (DOL) and siliceous (SIL) aggregate could be clearly seen. On the former

(L ef t): Kassie Botha, who looks af ter 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

T his proved too costly, so a method of incorporating a CAC/DOL corrosion control layer on a host pipe made of PC/ 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 the 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

(Above): A series of 250mm long pipe samples which were placed in a manhole during 2005.

layer was a wet-on-wet process and this

(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.

corrosion control layer was compacted into the host pipe, an affective bond and an aggregate interlock between the two layers was created. For many sewers with moderate to severe corrosion levels, the

preceding paragraph. Given that a host

use of a CAC/DOL corrosion control layer

pipe can meet the structural requirements

made for a more cost-effective solution

of a sewer and the corrosion control

than either the inert cast-in lining or

layer its durability requirements, and

the traditional dolomitic lining. Providing

providing that operating conditions and

conditions are not excessively aggressive,

effluent composition have been established,

this solution is applicable to pipe diameters

appropriate pipe choices can now be made

of 300 to 1 200mm.

to provide the most cost-effective sewer piping solutions. The CMA’s sewer design manual will describe how this is achieved.

tHe SeConD DeCADe After 12 years the deterioration of the three siliceous aggregate pipes was so

tHe Future - extenDIng tHe uSe oF

severe that they were on the point of

corrosion rates of the different materials.

tHe experImentAl FACIlItIeS

collapse. To prevent this, sewage was

The measured relative corrosion rates for

The information obtained to date is limited

diverted through the bypass section until

the unprotected materials, using a value of

to a few of the possible materials that

the necessary remedial work had been

1.0 for a PC/SIL concrete were:

could have been used as corrosion control

done. As had been anticipated, the 84mm

• 0.4 for PC/DOL

measures and there is still considerable

walls had disappeared completely in some

• 0.25 for CAC/SIL

scope for further refinement. With this in

sections, indicating a corrosion rate in

• 0.32 for FC

mind new 250mm long pipe samples have

excess of 7mm per annum.

• and an estimated 0.09 for CAC/DOL.

been placed in the manholes that were

The three badly deteriorated pipes

These values can now be used in the

constructed in the gaps left by the pipes

plus sections of pipes on either side of

predictive equations of the LFM, developed

that were removed. Placing these pipe

them were removed and replaced with

in the US and based on a PC concrete,

samples in manholes introduces a significant

manholes. Detailed measurements were

by adding a material factor equivalent to

change to the way in which inspections are

then taken to ascer tain the relative

the relative corrosion rates cited in the

done as it is no longer necessary to divert


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.

about. After a certain age they need to be 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 30% of the sewers up to 1 200mm

the flow through the bypass section. The

South Africa is the only country where a

pipe samples have removable top sections

section of live sewer has been set aside to

which can be measured and weighed. Such

test the performance of materials under

an exercise took place earlier this year and

very aggressive conditions. International

only applicable to a very small

indications are that the corrosion loss will

CAC suppliers have shown considerable

percentage of pipes less than 900mm

be measurable later this year, three years

interest in the new manholes and they

in diameter. Intended mainly for very

after the pipes were installed.

have co-sponsored the construction of a

aggressive conditions, they will

The additional samples placed in the

fourth manhole completed at the end of

compete with the other solutions on a

new manholes all consist of unprotected

2007. When used in the LFM, the data

project by project basis with pipes

concrete in three categories, namely:

gleaned from this project will also be ap-

• Concrete made using PC cement

plicable to other countries, in particular

with extenders • CAC linings integrally cast into the host pipes • And mortar-lined pipes using both PC and CAC.

diameters • Pipes with cast-in HDPE linings are

from 900 to 1 200mm in diameter • For pipes larger than 1 200mm in

those with developing economies. Many

diameter most sewers should probably

of these are located in warmer climates

be specified with a cast-in HDPE lining.

where sewer conditions are similar to or

There are two advantages in using

even more severe than those experienced

an HDPE lining on these pipe sizes. The

in South Africa.

smoother bore offers greater hydraulic efficiency, hence a smaller diameter can

These additional samples are intended to yield more accurate information than

aDDitiONaL cONSiDeratiONS

be used, and the cost of the lining

was the case during the first decade

Until quite recently sewers were designed

relative to that of the host pipe

o f measur ements. In par ticular, the

for a 40 year lifespan (one generation). This

decreases as the diameter increases.

per f ormance of the CAC linings with

shortsighted approach, especially when

T h e S o u th A f r i c an c on cr e t e p ip e

dif f erent aggregates and dif f erent

applied to sewers and other buried pipelines,

industry now supplies a full range of

proportions will be assessed, as will the

is highlighted every time a sewer fails.

sewer pipes, offering sewer owners and

Current thinking maintains that a sewer

designers the most cost-effective solution

should be designed for a much longer service

to meet the design-life requirements for

life, at the end of which rehabilitation rather

any sewer, no matter how aggressive the

iNterNatiONaL iNtereSt

than replacement should be the preferred

conditions. They will be further assisted in

Although there has been considerable re-

route. This means that outfall sewers

making the right pipe choices when CMA’s

search on sewer corrosion internationally,

should not simply be installed and forgotten

sewer design manual is published.

influence of various extenders on the performance of PC.

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 ICCX (International Concrete Conference & Exhibition), 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 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 Hans-Dieter 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 worldwide. For instance, the first Russian ICCX, ICCX St. Petersburg, was held in 2005. Russia, like South Africa, is 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 commented on to what

“Forty years ago precast concrete

precast framed structures. It would cer-

degree the technology, both in papers

was used in South Africa for large frame

tainly help in addressing the housing short-

delivered and in the exhibition itself, was

structures and then it was dropped. By

age and would provide less expensive and

applicable to South Africa. Having been

contrast, precast technology plays an

quicker methods of erecting structures.

based in South Africa for the past nine

important role in housing and other struc-

“For example, in Europe and America

years, where, through UCT he has been

tures in countries such as the USA, Italy

parking garages can be built to five star

involved in the concrete and more espe-

and Sweden. South African engineers tend

designs within six months. T hey ar e

cially the precast concrete industry, Dr

to be more conservative and like to con-

aesthetically pleasing, economical to

Beushausen was more than qualified to

vince themselves that a new technology

construct and durable. By contrast a

comment.

will work before they use it. Many of the

parking garage on Cape Town’s Waterfront

“Much of the technology on show at

technologies on show at Sun City were new

has been in the making for the past two

ICCX, especially precast concrete, is ap-

to South Africa, for example self-cleaning

years and we have no doubt it is going to

plicable to South Africa although some of it

concrete, but seeing them exhibited and

be considerably more expensive than a

is not being used to its full potential owing

being discussed in an international forum

precast equivalent would have been,” said

mainly to the mindset of some engineers

may well act as a catalyst to their intro-

Beushausen.

and architects who perhaps don’t fully

duction 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 picture 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

umns if engineers are reluctant to specify

which lists 100 advantages of using the

exhibition for producers on the one hand

them. Therefore engineers, architects

technology. It first appeared at ICCX /

and engineers and architects on the

and producers need to get together and

Berlin and a second version which

other. Producers essentially want to view

discuss the possibilities,” he said.

addresses sustainability, has just been

machinery whereas the professionals are

Dr Karutz observed that precast con-

published. The first book has been a best

interested in processes and systems. The

crete has made huge advances during the

seller and has been translated into several

course was run in conjunction with Federale

past 10 years.

languages. Both books can be viewed on

Internationale du Beton (FIB) and focused

“One o f the gr e a t ad v an t age s o f

the web via the British Precast Associa-

on precast concrete framed structures.

precast concrete is that it makes

tion on www.britishprecast.org,” noted

It was attended by 75 delegates most of

quality control much easier. For example,

Dr Karutz.

whom comprised engineers and architects

modern production plants are producing

Ad-media publishes three journals: the

although five delegates from local precast

precast panelling of up to 10 metres to

CPI journal which is published bi-monthly

manufacturing companies also attended. A

accuracies of 1mm. Because it is made

and is aimed at concrete producers; AI

similar course was run at ICCX in Cape Town

under conditions which are easier to

Aggregates International deals with the

where 100 delegates participated. Despite

control, precast concrete is generally

quarrying, processing and transportation

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

of raw materials for the

One of the great advantages of precast concrete is that it makes quality control a much easier process.

demand for precast concrete.

construction industry; and an architectural journal. The latter aims at generating new ideas in the uses of concrete. This is the only architectural journal which specialises in concrete. CPI is translated into eight

“Another technology with relevance for

of a higher quality and is more durable

different languages and 30 000 copies are

South Africa is high performance concrete

than its insitu counterpar t. Precast

circulated worldwide.

and a paper was devoted to it at the con-

structures should last longer and require

ference. It is still new to this country and

less maintenance.

companies are learning how to mix it and

In closing Dr Karutz and his colleagues noted that South Africa’s ICCX events

“One of yesterday’s speakers, Arnold

had been a resounding success, both in

van Acker, spoke about a 37 storey sky-

exposing local professionals to the exciting

“South Africa has only a handful of

scraper in Brussels which was originally

potential of modern concrete technology

large precast manufacturers and there

designed in steel but which was finally built

and by demonstrating the growth potential

is huge potential for the growth of the

as a 40 storey building using precast

of the South African construction industry

existing range of precast products and

concrete. Moerover, it was built three

to foreign companies.

the introduction of new technologies. This

months quicker than the steel design would

cannot be done in a haphazard fashion and

have taken.

how the mixing affects performance.

the industry must work together on this.

“Anyone interested in the benefits of

There is no point in building a new factory

precast concrete should get hold of a copy

to manufacture precast beams and col-

of Martin Clarke’s ‘Little Book of Concrete’

P

(Below): 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.



36 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008

the use of precast concrete tunnel segments on Gautrain 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

watertight, compressive gaskets are

implemented to ensure that the completed

installed around the entire perimeter of

tunnel lining is watertight.

each segment, in specially formed grooves. 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.

18m3 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 to the final placement of segments. The loading is also designed to handle the forces (4 000t) 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

(Top):Tunnel ring segments shortly after delivery to Gautrain’s Rosebank storage depot. (Left from top to bottom): The earth pressure balanced tunnel boring machine (EPB TBM) which is being used for boring the 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.


38 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008

and the finishing of arises. Should it be necessary, permissible concrete repairs are carried out, according to approved segment repair methods. Moreover, at this stage each segment receives an individual identification mark. They are then rotated 180° so that the intrados f ace up, and ar e moved to the nex t production station where gasket fixing takes place.However, before 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 minutes af ter the concrete has been

inside the tunnel. Once in place, pressure

poured and compacted, the mould covers

is applied to the neoprene gaskets, so that

are opened to allow for surface finishing

proper bonding is achieved. Thereafter a

and the application of an approved curing

curing compound is applied to the exposed

compound to the extrados. To prevent

concrete sur f ace bef ore a f ur ther

dehydration of the fresh concrete the

quality contr ol check is under taken.

mould is covered with a tarpaulin (Figure

T he pr oduction cycle is designed f or

5) f or 24 hour s a f ter casting, and,

a pr oduction output of one segment

proDuCtIon CYCle

provided that an early-age strength of

every 10 minutes, thereby achieving 42

The production cycle commences with the

15MPa has been reached, de-moulding of

segments per working day.

preparation of the moulds, including their

segments can then take place.

(Above): 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. (Top): A segment section is manoeuvred into position inside the TBM by a segment feeder shortly before it is vacuum lifted and placed into position.

cleaning, assembly and the application of

The segments are then transported

a releasing agent (Figure 3). Concrete is

to a temporary storage area for quality

The concrete mix consists of cement

poured into the moulds, and to prevent

checking. This includes an inspection of

CEM I 42.5N (350kg/m³), blast furnace

segregation, each mould is vibrated for

the gasket recess, minimum cover of

slag (100kg /m³ ), f l y ash (100kg /m³ ),

no longer than 300 seconds. Fif teen

reinforcement, extrados surface finishing,

aggr egates (19mm ma x size), water

MateriaLS


PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 39

and plasticiser. Workability calls f or

QUaNtitieS

(one ring of six segments per trailer). From

60mm slump concrete and the maximum

A total of 12 000 segments, consisting

the site storage area the segments are

water/cement ratio is set at 0.45. Each

of 17 420m³ of concrete and 1 437t of

lowered into the shaft by a tower crane

segment includes 95kg of steel rebar per

reinforcement steel, is being used to line

and transported in pairs to the TBM on

m³ which is accurately assembled with

the three kilometre tunnel. The reinforced

rail wagons. They are then forwarded to

the help of specialised jigs.

concrete volume of one ring is 8.71m³.

the point of installation on a segment

The minimum concrete cover to the

One standard or counter key segment

feeder and installed by the TBM’s vacuum

reinforcement is 30mm. In order to achieve

is comprised of 1 585m³ of concrete

segment erector.

the production of one segment per mould

weighing 4.1t (concrete density 2.55t/m³),

per 24 hour cycle the segments require

and one key element consists of 0.787m3

CHAllengeS / SolutIonS

an early-age strength of at least 15MPa

of concrete weighing 2.0t.

A huge advantage in the production of

after 20 hours and they should attain

the TBM segments has been the civil

a compressive cube strength (150mm x

StOraGe / traNSPOrt / iNStaLLatiON

contractor’s prudent selection of an

150mm) of at least 50MPa after 28 days.

Four thousand segments can be stored

established precast factory, run by an

Before they are finally installed in the

at SPC’s factory at any one time and 50

ex per ienced management team w i th

tunnel segments must attain a strength

rings (300 segments) can be stored on site

significant T BM segment experience.

rating of 55MPa. To ensure this three

next to the tunnel portal. The segments

The greatest challenges have related to

test cubes are cast for each batch of

are transported from the precast factory

developing the necessary standards of

segments and tested after 56 days.

to the tunnel site on special road trailers

workmanship and quality assurance to match the specification requirements.

The greatest challenges have related to developing the necessary standards of workmanship and quality assurance to match the specification requirements.

This has been successfully achieved by 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 on 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 Olievenhoutbosch Ministerial 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.


MiTek South Africa is a wholly-owned 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 buildings. MiTek’s ULTRA-SPAN system has been ( A b o v e ): O n e o f t h e f r e e - s t a n d i n g h o u s e s a t 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.

successfully exported to other parts of 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 at

ULTRA-SPAN, says that the system uses a

an average of 38m2 and 36m² respectively.

special galvanised steel, and was developed

The units have individual service connections

jointly with Marley.

and pine floors are being installed in the

“These trusses have excellent strength

double-storey units.

-to-weight properties and are quickly

Bigen Africa Ser vices, Road Crete

assembled and erected. They were deliv-

A f rica and L e f ika Constr uction wer e

ered on site as knockdown kits and were

responsible for infrastructure installation,

then assembled in accordance with MiTek’s

and Bigen Africa in conjunction with HAD

specifications by unemployed and un-

Services, designed and project-managed

skilled people.

the construction of the houses. Sea Kay

“Four roof assembly teams were trained from scratch by Marley in all aspects of roof

Engineering Services is the main topstructure contractor.

construction. MiTek handled the training on

Concrete bricks were the other major

the assembly of the trusses. Some of the

precast element on this project. Sedibeng’s

workers became so skilled that they have

Maxi brick measuring 290 x 100 x 140mm

were able to find similar employment on

and produced to a strength of 10MPa was

other construction sites.

used. After brick laying, the walls were

“Each team took 25 minutes to assemble

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.

(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.

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 project 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 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 the 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 an 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 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. Seventy metres long and seven metres high it was built at an angle of 70º. The fill in this wall is well compacted and reinforced with high strength polyester geogrids supplied by


PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 43

Kaytech. The fire escape sits directly on the structural fills and

A composite wall, it was constructed with a double skin up to a

applies loadings on 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 situated in the basement which houses the building’s

Another wall section, the south western pod, was built around

fire fighting equipment. Approximately 14 000 blocks were

a staircase. It is also a composite structure in which cement

used on this wall and Kalode were responsible for all the fills and

stabilised soils and geogrids as well as plain geogrid reinforced fills

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 with a 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 supplied by 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 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%.


44 PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008

Membership June 2008 COMPANy NAME

PHONE NO

FAX

PRODUCTS

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

00254 282 4478/9

n/a

P

035 791 1238

035 791 1235

P

021 875 5365/021

086 511 7070

M

011 310 1176

011 310 1178

P

00264 61 321 3009

00264 61 321 3041/2

MP

031 507 5525

031 507 7094

P

Bamburi Special Products (Kenya) Baybrick Boland Concrete Bosun Brick Midrand Brick & Concrete Industries (Namibia) Brickcast Industries 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 (H/O)

011 495 2200

011 495 2489

MPRT

Concor Technicrete (Mpumalanga)

013 758 1203

n/a

MPRT

Concor Technicrete (Mpumalanga)

017 689 2100

n/a

MPR

Concor Technicrete (Mpumalanga)

013 696 1153

n/a

MPR

Concor Technicrete (Free State)

057 391 4200

n/a

MPR

Concor Technicrete (Limpopo)

015 293 8083

n/a

MPRT

Concor Technicrete (Gauteng)

011 203 7700

n/a

MPR

Concor Technicrete (North West)

018 484 6234

n/a

MPR

Coastal Concor Technicrete

041 372 2230

041 372 2200

MPR

Concrete Units

021 386 1923

021 386 2514

Pi

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

P

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

087 940 2054

086 667 2037

S

Echo Prestress

087 940 2060

086 514 7342

S

Echo Prestress Durban

031 569 6950

031 569 6974

S

Fastfloor Botswana

087 940 2060

086 514 7342

S

Inca Concrete Products

021 904 1620

021 904 6115

MP

Inca Masonry Products

043 745 1215

043 745 1501

MPRT

Infraset

011 876 5500

011 872 1713

Pi

Infraset

012 652 0000

012 652 0132

PRT


PRECAST VOLUME 2 • ISSUE 1 • JUNE 2008 45

Infraset

031 569 6900

031 569 6903

PR

00267 392 2850

00267 392 2840

P

Klapmuts Concrete & Cape Retaining

021 875 5151

021 875 5665

R

Kopano

016 363 0340

016 363 0714

P

Kwena Brickforce (Botswana)

KuluCrete South Coast

039 685 4165

039 685 5166

MPR

Kwena Rocla (Botswana)

00267 392 2850

00267 392 2840

Pi

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 KZN

032 944 4155

n/a

T

Mobicast Mossel Bay

044 874 2268

044 873 3114

P

MVA

012 386 0050

012 386 0073

P

Monier Roofing SA (Gauteng)

016 430 8000

016 430 8068

T

Monier Roofing SA (Free State)

051 432 5089

n/a

T

Monier Roofing SA (North West)

012 250 2218

n/a

T

Monier Roofing SA (Cape Town)

021 534 1441

021 534 7851

T

*Monier Roofing SA (DBN)

031 565 1312

031 565 2911

T

*Monier Roofing SA (ELN)

043 743 2191

n/a

T

Monier Roofing SA (George)

044 878 1325

n/a

T

Monier Roofing SA (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

086 600 1520

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 Meyerton

016 362 4619

016 366 4581

P

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

Zenzele Brix

012 803 6884

086 510 9093

P

New Members 2008 M = Masonry

P = Paving

Pi = Pipes

R = Retaining Blocks

S = Floor Slabs

T = Roof Tiles


PRECAST VOL 1 JUNE 2007 25


Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.