Precast magazine • Issue 2 • 2017

ISSUE TWO • 2017

R49.00

THE CMA – QUALITY CAST IN CONCRETE

• Getting roofing right • Meccano-style V&A parkade • Why CBR walls fail

PROJECTS

COVER STORY 2

37 MAXIMISING PROPERT Y INVESTMENT

WHAT’S IN A MOULD?

INDUSTRY NEWS 5

CMA ACROSS THE COUNTRY

7

COASTAL FEEDBACK MEETINGS

8

GETTING ROOFING RIGHT

9

Q&A WITH THE CMA DIRECTOR

20

39

21 LONG-LASTING PAVERS 24 ENGINEERED SOLUTIONS

FOR SOUGHT-AFTER LUXURY APARTMENTS 27 12M-HIGH RETAINING

WALL SYSTEM

41 CONCRETE BIBLE UPDATED

TECHNICAL

12

40 ADDING GRACE TO

HOUSING DEVELOPMENT

41 PHOTO CORRECTION

GLOBAL VIEW

28

14 PRECAST ROADWAY

SOLUTIONS GLOBALLY

PRODUCTS

42

17 NEW PAVING BLOCKS LAUNCHED 17 DEMOULDING MADE EASIER

32 MAKING SAFET Y A PRIORIT Y

19 MASONRY MANUFACTURING MACHINES

34 COST-CUTTING LEADS TO

CBR WALL FAILURES

PRECAST is the mouthpiece for the Concrete Manufacturers’ Association - CMA Concrete Manufacturers’ Association Physical Address: Office 0400, Standard Plaza Building, 440 Hilda St, Hatfield, Pretoria Postal Address: Post Net Suite 334 Private Bag X 15, Menlo Park, 0102 Tel: (+27 11) 805 6742 Fax: (+27) 86 524 9216 E-mail: admin@cma.org.za Website: www.cma.org.za Publishers: Isikhova Publishing & Communications Postal Address: PO Box 651793, Benmore, 2010, South Africa Tel: (+27 11) 883 4627 Fax: (+27 11) 783 2677 Website: www.isikhova.co.za Publisher: Andrew Meyer Tel: (+27 11) 883 4627 E-mail: andrewm@isikhova.co.za Consulting editor: Raymond Campling Tel: 076 297 2775 E-mail: media@mediasavvy.biz

Coastal editorial: David Beer Tel: 082 880 6726 E-mail: david.bigsky@gmail.com

ISSUE ONE • 2017

R49.00

THE CMA – QUALITY CAST IN CONCRETE

Advertising: Wally Armstrong Cell: 083 701 3278 E-mail: wallyarmstrong@outlook.com Subscriptions/Accounts: Thuli Majola Tel: (+27 11) 883 4627 E-mail: subscriptions@isikhova.co.za Design and layout: Joanne Brook E-mail: joanne.studio@isikhova.co.za The views and statements expressed in this publication are not necessarily those of the editor or the publishers and neither the publishers nor the CMA accept responsibility for them. No person connected with the publication of this journal will be liable for any loss or damage sustained as a result of action following any statements or opinions expressed herein. The same applies to all advertising. Precast© 2017. All rights reserved. No part of this magazine may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage retrieval system, without prior written permission from the publishers.

Endorsed by:

• Getting roofing right • Meccano-style V&A parkade • Why CBR walls fail

ON THE COVER PMSA believes that a mould is one of the important tools in the brick, paving and hollow block precast manufacturers’ arsenal, as it has an immediate and direct impact on production in terms of volumes and quality produced. Contrary to the belief of some in the concrete manufacturing industry that a “mould is a mould”, there is sufficient evidence to prove that a carefully designed and well-made mould has the potential to turn a small profit into a bigger one.

COVER STORY 2

WHAT’S IN A MOULD? Contrary to the belief of some in the concrete manufacturing industry’s that a “mould is a mould”, there is sufficient evidence to prove that a carefully designed and well-made mould has the potential to save valuable time and material, increase productivity and turn a small profit into a bigger one.

In fact, a mould is one of the important tools in the brick, paving and hollow block precast manufacturer’s arsenal, as it has an immediate and direct impact on production in terms of volumes and quality produced. Well-manufactured products also have indirect advantages further down the process, as there will be fewer rejects and packaging is simplified due to uniformity of shape and size.

According to Quintin Booysen, PMSA sales and marketing manager, a quality mould will also produce more drops than standard ones and specialised wearresistance steels used in the manufacture of a mould will ensure that it maintains its dimensions to ensure uniformity of size and shape of the products produced. PMSA also offers more advanced moulds with replaceable wearing strips, mould inserts and shoes that can provide further advantages in terms of longevity and serviceability. Despite a higher initial purchase price, these deliver improved costs of ownership in the long run.

Massive savings “For example, in a standard bevel paver of 100 x 200 x 60mm, the product should weigh approximately 2,52kg. If it were to wear-down just 1mm all around, it could lead to an extra 80g of material being required per unit. To put this into perspective: if a manufacturer makes 84 000 units per day, it can equate to an extra 134 tons of concrete or the equivalent of the material to produce 53 000 pavers per month. Using the same example on a maxi brick 290 x 140 x 90 mm, an extra 332 tons of concrete per month would be used due to only 1mm wear all round on a mould.

“A quality mould will produce more drops than standard ones.”

PRECAST | ISSUE TWO | 2017

pricing and contribute further towards

possible returns on investment and give

reducing the cost per unit produced by

buyers the edge in a hotly contested

them,” says Booysen.

industry,” says Booysen.

According to Anthony Gracie of Cape Brick, the initial price of the PMSA Rock

Market-driven

Solid moulds is approximately one-third

As a wholly-owned, local company PMSA

mor e ex pensi v e than compe ti tor s’

also had the advantage of involving cus-

moulds, but have up to double the life-

tomers throughout the process of devel-

span with better tolerances and more

oping its range of moulds. This input and

accuracy, This ensures the products

refinement has led to the evolution of

are symmetrical and the right weight,

its moulds to the point where concrete

which amounts to big savings in mate-

manufacturers with PMSA moulds are

rial as well better equipment availability

getting more drops out of them due to

and vastly improved operational costs.

better surface hardening techniques

Booysen concludes that this type of

and materials being employed by PMSA.

attention to detail can give manufactur-

He adds that in the case of PMSA

ers a considerable advantage over com-

and its branded Rock Solid range, qual-

petitors through improved operations

ity is standard, with customers being

and lower life-cycle costs. “With good-

able to select the right kind of mould

quality aggregates, capable machines,

for their requirement in either solid,

correct settings and the right moulds,

welded or bolted moulds. “We looked at

manufacturers can set themselves up

different solutions based on common

to succeed. With the right maintenance

requirements of our customers and

and support from PMSA, their opera-

developed products to match these,”

tional success is another step closer.”

says Booysen.

The company also invested heavily in technology to manufacture moulds that can compete with the very best in the world. But, says Booysen, local concrete manufacturers also enjoy the benefits of dealing with a home-grown company with fast turnaround times and easy access to spares. The additional access to technical support is a windfall and many a manufacturer has benefited from expert advice of PMSA support staff when servicing or selecting moulds that

(Above): Walter and Robert Ebeling of PMSA.

best suit their operations.

(Below and left): A premium-quality Rock Solid mould on display at the Totally Concrete 2017 exhibition.

Well supported “As a result, the savings on concrete

Customers also have access to PMSA’s

and labour over the period of this month

bespoke moulds that can be designed

are close to or even exceed the cost of

inhouse to strict requirements, with the

a quality new insert on a bolted mould.

additional benefit of being able to provide

But monetary value aside, of more con-

advanced surface finishes to create

cern to manufacturers should be that

unique and eye-catching products. This

units entering the marketplace from

type of ability allows manufacturers

worn moulds will be irregularly sized and

to move from a low-value product to

more difficult to place. This makes the

a higher-value product while still using

work of installers more difficult. As a

the same materials, processes and

result, the pavers will become unpopular

equipment.

among the workforce and probably not be purchased again.

“Among the examples of our moulds in operation is Cape Brick, where our Rock

“Fur thermor e, our f indings have

Solid moulds have increased the mould

shown that quality moulds actually play

replacement intervals to almost double

a critical role in sustaining high levels

before needing a mould insert replace-

of production. As a result, we focus

ment. Even when they are worn, parts

our attention on manufacturing rugged

of the mould can be re-used to reduce

PRECAST | ISSUE TWO | 2017

COVER STORY

and reliable moulds that deliver the best

3

YOUR QUALITY MARK IN PRECAST CONCRETE

Obtain your mark of approval from the leading authority in the precast concrete industry.

TRUST THE INDUSTRY EXPERTS Address: Office 0400, Standard Plaza Building, 440 Hilda Street, Hatfield, Pretoria, 0083 Tel: (011) 805 6742 • Email: admin@cma.org.za • Website: www.cma.org.za

INDUSTRY NEWS

CMA ACROSS THE COUNTRY While the political landscape has changed forever and revelations of state capture

5

make for nervous times, the Concrete Manufacturers’ Association has been quietly going about its business to pave the way for improved trading conditions for the industry – even in trying economic times.

During the most recent round of regional meetings, executive director Frans Minnaar gave members insights into what has been an extraordinary year for the association. Successes and challenges

and addressed questions surrounding

the CMA Certification Service (CMA CS),

have been in equal measure and the overall

the end of an era during which cement

which had enabled the CMA to generate

result is that the association is emerg-

producer PPC acted as one of the main

money and assist in funding its efforts.

ing stronger and more self-sufficient

sponsors and supporters of the CMA.

than ever before. Self-sufficiency does

“Members will recall that PPC agreed

not mean isolated, though; by contrast,

to suppor t the CMA

While the CMA actively pursues growth

one of the first topics of discussion on

through tough times af-

through expanding its membership base,

the regional agendas was

ter the recession and

the CMA CS already finds itself with full

the CMA’s wholehearted

subsequent turmoil in

order books and a growing customer

endorsement of the

the economy. With the

base – which bodes well for the future.

industry’s very own

association now on an

Although the service is still awaiting

Concrete Confer-

even keel and able to

SANAS accreditation, this has not de-

sustain itself, the PPC

terred manufacturers who are growing

agreement has been rescind-

increasingly anxious about the traditional

of the members of the

ed and we remain grateful for its

service provider, the SABS, and its ability

newly-aligned Concrete

support. As with every down-cycle,

ence. T his marks the first collaboration

Industries body which

crete Institute (TCI) and the Concrete Society of Southern Africa (CSSA).

The conference will take place on 17 and 18 August 2017 at the Misty Hills Conference Centre in Muldersdrif t, featuring presentations, case studies, how-to discussions and exhibitions that will showcase the country’s concrete abilities. The Concrete Conference will provide an opportunity to learn and en-

to provide timely certifications.

there’s also a natural upside, as headline

includes the CMA, the Southern Africa Readymix Association (SARMA), The Con-

Certifiable quality

Members’ complaints about the SABS include:

“The CMA has been quietly going about its business to pave the way to improve trading conditions for the industry.”

• Out-of-date certificates as a result

of excessively long waiting lists.

• Deferment letters which are issued

instead of actual certifications.

• Product buyers questioning the valid

ity of these SABS letters.

• Fears that unscrupulous manufactur

ers are taking advantage and operat-

ing from SABS letter to letter.

• The industry is questioning manufac

turers’ products, as they do not have

able delegates and exhibitors to network

sponsorships that had been automati-

confidence in current certification

and showcase their products. All CMA

cally held by PPC are now available to eve-

processes and some are opting to do

members can participate on a first-come,

rybody, which means associate members

first-served basis. “It’s about time that all

or suppliers may now secure exciting

“CMA members can rest assured

the concrete bodies stood together as a

sponsorship deals to brand and market

that CMA CS is aware of this sad state

united concrete industry. There’s also no

their products among CMA members.”

of affairs and is working hard to assist.

their own audits.

need for concern about working together,

Minnaar showed the positive state of

The CMA CS work ethic is considerably

as we each remain strongly independent,

the CMA’s financial affairs and allayed

more impressive. Since its inception in

but united in concrete,” said Minnaar.

concerns over the liquidity of the asso-

March last year, the team have set up

ciation, assuring members that meas-

the entire company structure, developed

Money matters

ures had long been in place to reduce the

their own quality management system

Minnaar brought members up to date

association’s dependency on sponsors.

for members to address ISO 17065 and

with the finances of the association

Among these was the establishment of

handed the documentation to SANAS.

PRECAST | ISSUE TWO | 2017

Further achievements

Coverland and Marley. Minnaar also

aren’t quite as quick or responsive as the

Wrapping up the proceedings, Minnaar

praised Precast magazine, which is grow-

CMA’s own service. At the time of the

mentioned other achievements, such as

ing in stature and expanding its reach

regional meetings, the CMA CS had al-

the success of Internet marketing, work-

to a distribution list of 5 000 individuals

ready awarded accreditation certificates

shops and the growth of Precast maga-

and growing.

to nine members, with several more set

zine. The revamped website continued

to follow,” said Minnaar.

to be a popular destination, with many visits daily. The paving

The efforts of the electronic and print publications dovetailed perfectly with the association’s other

Steady membership

workshop given by Tony Mc-

efforts to inform and educate

Meanwhile, despite the challenges the

Cormack, expert and author of

the market and provided a

industry has faced, membership of the

www.pavingexpert.com, was a

basis from which members

CMA remained constant, with new mem-

great success and was well at-

could access further informa-

bers filling in for some natural attrition.

tended by members in Gauteng,

Currently the membership stands at:

the Western Cape and KwaZulu-Natal.

tion in the form of booklets and training courses.

Producer members

84

The legal liability workshop, in conjunc-

Minnaar concluded the regional meet-

Non-producer members

21

tion with EOH and presented by Advocate

ing by reminding members to begin

Associates 10

G Augustyn, was also well received, as

preparations to enter the CMA Awards

Contractors 5

was the rooftile workshop which was

for Excellence and look out for details

Cement producers

presented by Avenge Infraset, Monier

about the new-format awards.

4

there should be broader representation of CMA member activity in Precast, for example of roofing company members.

Minnaar also discussed the structure of the CMA board of directors. Currently there is no-one with technical expertise on the board and he posed the question as to whether board membership should be extended to non-CMA members.

Danie Hattingh suggested that the

COASTAL FEEDBACK MEETINGS

CMA change its constitution at the next AGM to allow external experts to join the board.

Coastal feedback meetings took place

ing longer than expected. Nevertheless,

in Cape Town, Durban and Port Eliza-

he said he expected the accreditation to

Good year

beth. Venues and refreshment for the

come through by the end of June.

During his presentation, Cockcroft spoke about achievements of the past year.

Cape Town and Durban meetings were sponsored by CMA members Afrisam

Setting standards

These included seminars and workshops.

and Corobrick respectively. As in Johan-

During the Cape Town meeting, Brian

He said the paving workshop given by Tony

nesburg, these meetings were presented

Cook of Concrete Units suggested that

McCormack had been particularly suc-

by CMA executive director Frans Minnaar

the CMA encourage all its members to

cessful, especially in Cape Town, which

and marketing manager Henry Cockroft

use the same standards system. Devi

was attended by 120 delegates. He at-

and included active participation from

Lategan of Lategan’s Sementwerke

tributed this achievement to the crucial

members who attended.

noted that SA is in a process of evolving

role played by Cape-based CMA members

Minnaar spoke about the financial

and that the government is pushing for

in encouraging attendance, especially of

status of the association and stressed

alternative construction materials and

paving contractors.

that it is on a sound footing, despite the

methods. He said it is essential that

Cockcroft reiterated that CMA CS

fact that sponsorship is no longer be-

the CMA continues to promote precast

will have a hugely positive impact on the

ing received by cement producer PPC.

concrete and that cement producers be

association. He said the CMA CS mark

Revenue is now entirely driven by mem-

made aware of this.

is already appearing on precast concrete

bership fees and the CMA Certification

Danie Hattingh of Monier Coverland

products across the country and this

Services (CMA CS) mark of approval and

Cape Town asked for a breakdown of the

is helping to promote the CMA and its

accreditation process.

distribution of the precast concrete

members as a precast elite. He added

There is a definite need for CMA CS

magazine, Precast, as he felt it was aimed

that the CMA is about to embark on skills

auditing and several members are now

mainly at senior management and did not

training, beginning with paving, for which

using the system. Minnaar stressed that

filter down to the middle management

there is the greatest demand. With this

CMA CS has not yet received SANAS ac-

and contractors in sufficient numbers.

in mind, the association is currently up-

creditation and that this process is tak-

Juliano Amodio of Marley Roofing felt

dating all its training material.

PRECAST | ISSUE TWO | 2017

INDUSTRY NEWS

Unfortunately, it seems, that SANAS

7

INDUSTRY NEWS 8

GETTING ROOFING RIGHT When it comes to roof tiling, the standard

use of them. Workshops such as these

excess heat in summer. Other modern

of installation does not always match the

presented by the CMA are a worthwhile

roof innovations, such as tile clips, metal

quality of the product. This can lead to

intervention and we hope to see more in

ridge trees and breathable roll underlays,

failures or inefficiencies of roofs’ drainage

future,” said Hattingh.

were also displayed as a means of simpli-

or insulation performance.

He also shed light on emerg-

fying installations and making them more

Knowledge is key in roof-

ing trends in the three main

ing and the CM A r e c en tl y

regions where the workshops

The workshop culminated in a talk by

embarked on a series of work-

were being offered, including

Craig Allen of new CMA member com-

shops hosted by some of the

Johannesburg, Cape Town and

pany Ecomatch on the recycling of roof

country’s top professionals to

Durban. Although dif ferent

and concrete waste products on site.

upskill architects, contractors

roofing materials such as steel

This innovation allows materials to be

and the roofing industry to

are still popular in these areas,

collected, processed and re-used on

share best practices for the installation

tiles have a distinct thermal advantage.

construction sites as fill materials or

of efficient roofing systems.

They also have an air flow, which is absent

aggregate replacements.

First up, Danie Hattingh from CMA

in steel. He explained the thermal values

member company Monier Coverland

of roofs, R-values, SANS 10400 dealing

shared insights into an industry that

with roofs, how to install and test roofs,

has seen skills development almost grind

as well as the benefits of concrete roof

to a halt in the past few years. This has

tiles for climate control.

resulted in a pool of installers who have

Grant Uys of CMA member company

little or no formal training – and instal-

Aveng Infraset then demonstrated the

lation standards that are beginning

techniques discussed, including that of

to slide. “There are, however, private

dry-ridging. This technique is preferable

energy-efficient.

(Left): Danie Hattingh of Monier Coverland.

(Above): Delegates across the country attended

training companies out for there and it’s in until the such installation energy-efficient Final material will not be supplied print/publication time as of approval is received. Please return faxtile to:workshops 086 509held 4850 the recent CMA roof in up to installation companies to make

roofing systems, as it is able to dissipate

different regions.

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INDUSTRY NEWS

Q&A WITH THE CMA DIRECTOR Precast talks to Frans Minnaar, director of the CMA, about the implications of PPC’s cessation of its monthly sponsorship of that organisation Precast: Now that PPC has ended the

Obviously, now that the PPC sponsorship

monthly sponsorship to the CMA, where

has ended, there are more opportuni-

will the CMA obtain sufficient funds to

ties for companies – either members or

continue representing the precast con-

non-members – to sponsor promotional

crete industry?

events organised by the CMA for the

FM: Apart from sourcing sponsorship

benefit of the precast industry.

9

from other entities in the industry for promotion of precast concrete, the CMA

As a non-profit organisation, what percent-

also registered a new company, which

age of the funds raised for these events is

is a profitable one providing a “mark of

ploughed back into the precast industry?

approval” on the quality of precast prod-

As I’ve explained, the running of the CMA

ucts. This company is called CMA Certi-

NPC is funded with the membership fees

Companies can become involved in dif-

fication Services and, in compliance with

and sponsorships – such as the one we

ferent ways, such as providing venues,

the necessary requirements to obtain a

received from PPC – were utilised for the

sponsoring venues, sponsoring costs for

mark of approval, will issue the CMA CS

promotion of precast concrete products.

arranging presenters or providing lectur-

mark to a producer. This is a mark that

ers for workshops and training, obtaining

can be displayed on documentation or

How are the funds spent?

materials needed for these events, etc.

products, like the well-known SABS mark.

The CMA is organising different events such

These events are announced in advance

Since the CMA NPC is a non-profitable

as seminars, workshops, expos, industry

to the industry through different data-

company, the funds generated by CMA

meetings, technical committees, technical

bases, websites and cold calling.

Certification Services will be used to fund

workgroups, technical support, websites,

the CMA NPC in the future.

Facebook, etc, where the fundings raised

Since cement is a key ingredient in con-

through sponsorships are used.

crete, it made perfect sense for a cement

How were PPC funds used in the past

producer to sponsor events and be guar-

and what role did these play in developing

What events are earmarked for the rest

anteed of a high return on their investment

the industry?

of the year?

through branding efforts. Surely the same

The PPC sponsorship money benefited

During this financial year, dif ferent

branding proposition is present for suppli-

the CMA members in that it was used for

events are planned, such as a rooftile

ers of other materials and services?

the promotion of precast concrete prod-

installation workshop, a legal liability

That’s 100% correct: it’s not only the ce-

ucts, as well as ensuring that the CMA

seminar, a concrete pipes and culvert

ment producers that could benefit from

had some back-up money for promotion of

seminar, a concrete masonry seminar,

sponsorships of these events. There are

precast concrete when sponsorships are

development of a registered training

numerous manufacturers of equipment

difficult to obtain in bad economic times.

course for paving installation, the re-

used in the precast industry, chemical

The PPC sponsorship was only utilised for

view of installation manuals for different

additives and admixture manufacturers,

this purpose, since the membership fees

products such as paving, roof tiles, pipes

retailers of precast products, associa-

of CMA members were used for funding

and culverts, and participation in the new

tions and institutions, etc.

the running of the business.

Concrete Conference that’s taking place in August this year.

What are the costs?

The costs are determined by the type of

With the important role that this type of funding played in the many events hosted

How can companies become involved

event, where it will be arranged (through-

by the CMA, what opportunities exist for

in making these events successful and

out the country), how many sponsors

others to become involved and sponsor

how can sponsorship opportunities be

are involved, what type of audience is

these events?

identified?

targeted, etc. To determine what costs are involved or could be sponsored, it’s necessary to contact the CMA and discuss the possibilities.

Who should be contacted there?

Contact the CMA head office on tel: 011 805 6742 or the marketing manager, Henry Cockcroft, on tel: 011 805 6742 or 081 721 7701, or email: marketing@ cma.org.za.

PRECAST | ISSUE TWO | 2017

IF YOU THINK PRECAST CONCRETE,

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ACTURER

S

A OCI

NCRETE

SS

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THINK CMA PRODUCER MEMBERS.

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Address: Office 0400, Standard Plaza Building, 440 Hilda Street, Hatfield, Pretoria, 0083 Tel: (011) 805 6742 • Email: admin@cma.org.za • Website: www.cma.org.za

CATCH US ONLINE Precast magazine has gone digital with the introduction of an all-new website and online page-flip magazine.

The digital site supports our growing print footprint and gives those interested in the subject of precast concrete in Southern Africa the chance to access the magazine, no matter where they are in the world.

The www.precastmag.co.za website also gives visitors comprehensive information about the publication, contacts and details of all involved in the compilation and production of the magazine, as well as advertising and subscription information.

For tech-savvy readers who prefer digesting their concrete news digitally, the page-flip version of the magazine allows them to access and page through the magazine from multiple platforms, including PC, Android and Apple devices.

Another clever feature of the site is the listing of advertisers, which includes details and contact information for quick and easy reference, should a reader want to contact them.

Andrew Meyer, CEO of Isikhova, the publisher of Precast magazine, says the decision to go online is aimed at giving readers the choice of receiving the publication in the format they prefer.

“These days we have options and it’s our intention to give readers the news they want, the way they want it, when they want it.”

WARNING: ACT ON NON-PAYMENT Non-payment and late payment of accounts in the construction industry are becoming more of a problem as customers feel the pinch of SA’s credit downgrade and the resultant unease in the overall economy.

Frans Minnaar, executive director of the Concrete Manufacturers’ Association, says the risk of non-payment is set to increase as credit costs escalate because of worsening lending conditions. “Rising interest rates can have a real effect on affordability of credit and this may lead to difficulty for some in repaying debts. As most contractors make use of finance to undertake their projects, the rising cost of credit may also lead to reduced overall profit for them, which in turn affects affordability of products and the ability to pay suppliers,” says Minnaar.

“Non-payment or late payment is therefore a real risk and concrete manufacturers should take the necessary precautions to ensure customers are able to pay. They should also be proactive and ensure that all contractual dispute procedures, guarantees, etc are in place before supplying products.

“Even big municipal and government projects may run into affordability problems in future, so it’s wise to ensure that all the necessary precautions have been taken before commencing supply of products. Manufacturers shouldn’t be afraid to exercise their rights and be prepared to lose the contract, rather than supply products for which they may never be paid.”

PRECAST | ISSUE TWO | 2017

INDUSTRY NEWS

(Bottom left and left): Side-of-the-road block-makers do not produce the required quality of blocks due to inferior mixing and moulding techniques, as well as poor material selection and curing regimes.

(Below): Some of the symptoms home-owners can expect when buying side-of-the-road concrete blocks to do renovations.

12

CHEAP BUILDING BLOCKS CAN COST LIVES The price of buying crudely manufactured

average that allows for quality blocks

exists in the industry today. This is

roadside concrete (masonry) buildings

to be manufactured. The consequence

threatening a similar fate for others

blocks may be higher than consumers

is that only roadside manufacturers

throughout the rest of the country. The

think, especially in the event of a struc-

using manually operated equipment and

bad news for consumers is that the de-

ture collapse where damage is caused to

the cheapest raw materials are able to

mise of specialised, formal block manufac-

properties – or, worse still, if lives are

survive and produce inconsistent quality

turing capabilities will have the inevitable

lost as a result.

building blocks.

consequence of a demise in the quality of

T he unf or tunate consequence of

This type of practice has already led

consumers seeking the lowest cost of

to the complete collapse of the concrete

building materials is that prices have

block manufacturing industry in Gauteng,

No consistency

plunged far beyond the sustainable

where not a single large-scale producer

According to Frans Minnaar, executive

“Consumers need to know that the only other way of selling a block much cheaper than mainstream manufacturers is cutting on the input costs.”

new houses and structures built.

director of the Concrete Manufacturers’ Association NPC (CMA), there is a vast difference between professionally batched and mixed concrete using goodquality materials versus roadside mixes.

In addition, the equipment used to manufacture bricks in accredited factories is designed to properly batch, mix, vibrate and remove air pockets from moulds and precisely compact the concrete within closely set parameters.

By comparison, hand-mixed concrete is much less precise and can vary by as much as 50% per block. This means that strengths are usually inconsistent and fall far short of specified quality standards. “Even in the toughest economic circumstances, it doesn’t pay to build critical structures out of inferior products – it simply isn’t worth the investment,” says Minnaar.

“What’s the use of building on a fancy new lounge or bedroom at a considerable cost, only to find that the structure fails in a year or two and the walls begin to crack or seep water and eventually fall over? My guess is that if a home-owner

PRECAST | ISSUE TWO | 2017

wages. This sets the price within ap-

ing to fail, they wouldn’t buy them in the

proximately a 10% range of similar quality

first place – no matter how cheap they

blocks, with the only viable way of making

might be.”

more money being to sell more blocks.

Pricing model

that the only other way of selling a block

He explains that all manufacturers follow

much cheaper than mainstream manu-

a similar formula and have similar input

facturers is cutting on the input costs

costs that determine the price of blocks.

by using inadequate equipment, either

This includes the cost of cement, sand

reducing the quality of sand and stone,

and stone used in the mix. Capital costs

or reducing the amount of cement used

of decent equipment need to be factored

in the mix and paying workers an unfair,

in, as does the cost of labour and decent

unsustainable wage.

INDUSTRY NEWS

knew upfront that the blocks were go-

Consumers therefore need to know

Unsuspecting buyers of these blocks

Traditional dwellings

can expect the following problems with

“Perhaps there’s still a use for roadside

structures:

blocks in the building of rural low-wall

• Severe structural cracking.

traditional dwellings, where mud and

• Straight-line cracking through blocks

cow manure was used previously, as they

vertically and horizontally.

provide similar strength characteristics.

• Shrinkage cracking of blocks.

But in formal housing, there’s no place

• Inability to bear a load on the wall for

for these blocks and we strongly advise

everyday items such as roofs, gates,

consumers to stay away from buying

washing lines and carports.

these cheap alternatives,” says Minnaar.

• Crumbling sides and eventual collapse

PRECAST | ISSUE TWO | 2017

13

of blocks under load.

“When it comes to buying blocks for houses and walls, it pays to do research

• Wastage during the building process.

upfront to avoid problems. Speak to us

• Water seepage.

or visit our website and view the lists of

• Damp problems.

CMA members at: www.cma.org.za.”

GLOBAL VIEW 14

PRECAST PROVIDING ROADWAY SOLUTIONS GLOBALLY In places like India and the USA, engineers are working feverishly to develop precast concrete road solutions to overcome separate and distinct challenges in their own countries.

developed to provide mobility in many of

However, the solutions found abroad

the erosion of services and infrastructure.

the country’s crowded streets. Here, every last centimetre of space is occupied by traders or taken up by households.

Without road infrastructure, these communities are at risk of becoming isolated, which can stifle development and lead to

may have particular applications in SA that can either be redeveloped for local

Versatile precast

conditions or taken as part of a solution

However, the problem in many of these

towards developing much-needed road

areas is that heavy equipment such as

infrastructure – and even to overcome

graders and rollers simply cannot trav-

the maintenance backlog that has for so

erse the lanes and alleyways to get there.

immediately af ter being laid. T hese

long dogged our roadways.

In addition, many of the roads earmarked

solutions employ traditional brick and

In India, studies show that the use of

for paving are themselves too narrow to

block-type precast concrete pavers,

precast concrete for roadways is being

allow traditional road-building equipment

as well as new methods that employ

to work effectively. Other in-situ methods

fibre-reinforced concrete moulded to

have similar shortcomings, mainly due to

various shapes and sizes, depending on

space or lack of support networks, while

the requirement.

“Without road infrastructure, rural communities are at risk of becoming isolated.”

still others fail due to premature usage in these crowded areas.

Where areas are fairly undulating due to lack of compaction and road-making

To overcome this Catch-22, Indian

equipment, the road can still be paved

authorities are pursuing solutions to

using manual labour and pavers which

build precast roads that can be deployed

are specially made to suit the terrain.

comparatively rapidly and be used almost

These can be moulded and adapted to the

PRECAST | ISSUE TWO | 2017

the concrete elements will also reduce as

flexure. These pavers are relatively easy

work can be performed off-site at the

to produce in mechanically cast plants

precaster’s facility. Secondly, the period

They can be almost free of shrinkage

for which the lane is out of service can

and cracking and are more robust in the

be scheduled to off-peak traffic hours,

handling and placement process.

because construction can take place at

What is more, the precast concrete is durable and maintains its structure

roads get longer and demand for products increases. In addition, the precast concrete is manufactured under controlled environments, which leads to increased durability and lower maintenance costs.

The study shows that precast concrete solves traffic mitigation problems on three fronts. Firstly, total time to complete the project is kept to a minimum, because the majority of the

night and the repaired area can be opened to traffic for the morning rush.

better than other road types in harsh environments. In parts of India, roads

Longer-lasting

may be subject to prolonged wet periods

Finally, the construction footprint is kept

of monsoon-type rainfall, followed by

to a minimum. PCPSs require only a sin-

extended dry cycles. Precast roadways

gle lane to be closed on two-lane roads,

tested under these conditions have

including the shoulder. When there are

remained operational throughout these

more lanes and an interior lane needs

cycles, with little impact on the struc-

work, the interior lane and an adjacent

ture of the roadway.

lane need to be closed to safely accom-

Studies also found that wear surfaces

modate equipment and workers. In either

under all conditions were good and roads

case, traffic can continue to flow while

lasted for many years without signifi-

the repair is underway.

cant deterioration. This suggests that

The other advantage of using PCPSs

precast is a suitable solution for dense

is precast concrete’s proven durability.

urban areas and can withstand harsh

PCPSs are designed to last, with the

conditions. But how do they stand up

same criteria as new roller-compacted

to the challenges of large, high-volume

concrete construction that has an ex-

roadways with faster speeds?

pected lifespan of over 50 years. The material’s precision and quality are de-

Limiting congestion

rived from the plant-controlled conditions

In the USA, precast concrete road sur-

of the precast facility. Internal quality-

faces are being manufactured and tested

control inspection and testing ensure

precisely for these types of conditions.

a high-quality product. Furthermore,

The challenge in the USA is mainly due to

a quality product is achieved through

massive traffic volumes that make lane

inspection of the precasting process

or entire road closures difficult, if not

and field testing of the installed product.

impossible. As a result, the solutions be-

SA, with its increasingly congested

ing sought are centred around the speed

roadways, can learn from these stud-

lie of the ground if it is uneven. Larger

of manufacture of roads, using large

ies. In dense urban settlements, the

pavers (or even panels) have the ability

precast slabs to reduce road closure

use of bricks and pavers can provide a

to cover more ground and are therefore

times. Simultaneously, there is a need

long-lasting, low-maintenance solution

quicker to construct with less effort,

to reduce maintenance requirements,

to uplift communities and connect them

but require even terrain and reasonably

which may also affect traffic.

with transport nodes and centres. Like-

well-prepared sub-bases.

Studies at the School of Civil Engineer-

wise, large cities like Johannesburg and

ing Purdue University found that although

Cape Town can ill afford traffic conges-

Fibre reinforcement

the precast slab or panel methods being

tion and the benefits of precast concrete

T he use of fibre-reinforced cement

employed at present have a higher con-

roads are many. Perhaps it is time for

helps to prevent cracking under high-

struction cost, they offer the advantages

our municipalities and road authorities

moving traffic volumes and gives the

of speedy laying, which results in less

to start engaging with the CMA and its

concrete better compressive and impact

traffic congestion and fewer delays, as

members to find precast solutions for all

strengths, while also allowing a level of

well as lower user costs. The costs of

our roadways.

PRECAST | ISSUE TWO | 2017

GLOBAL VIEW

“Precast concrete is manufactured under controlled environments, which leads to increased durability.”

15

10023926JB/E

No matter what the job, our range of cement products will give you the quality you need for your build.

Want to know more?

Call us on 0800 CEMENT (236 368) or visit www.ppc.co.za

duced a fresh design option for landscape architects and paving contractors with the launch of Santigo, a new paving block produced in an attractive textured finish.

Aveng Infraset Landscape Products

NEW PAVING BLOCK LAUNCHED

sales manager, Brennan Small, says

rumbled finishes for added visual and

Santigo complies with current trends

design diversity,” advises Small.

“In addition, we produce paving blocks, kerbing and retaining wall blocks in

in landscape design, which favour larger,

Requiring only 17 blocks per square

our Masa plant, which is also located

more cost-effective pavers and is ideal

metre, the 240 x 240 x 50mm block is

at Rossway. Both Columbia and Masa

for shopping and community centres,

easy and cost-effective to install. An

manufacture state-of-the-art plant and

retirement villages, patios, driveways,

added advantage is that the blocks are

equipment which enable us to introduce

walkways and pool surrounds.

manufactured with bevelled edges on one

new and, in many instances, unique prod-

“Santigo has been designed to be laid

side and straight edges on the other. As

uct options for landscape architects and

in conjunction with our Masonique and

they are cast in body-through colours,

other construction professionals.

Cottage Stone pavers, thereby creat-

they can be laid either way, ie they are

ing greater scope for attractive design

fully reversible.

“Our Masa plant includes steel production pallets for enhanced vibration

and layout options. These would typically

“Santigo is a high-quality product

transference, in-line washing and seal-

comprise a Santigo body combined with

which complies with SANS 1058:2012.

ing, ageing and waving techniques and

either Masonique or Cottage Stone, or

It’s cast to high tolerances at Aveng

a specially insulated curing chamber. It

both, as borders/header courses.

Infraset’s Columbia plant at Rossway,

also boasts an advanced colour blending

“Santigo is available in three of f-

Centurion, using a vertical manufacturing

facility which is faster and more accu-

the-shelf body-through colours – grey,

process which guarantees that it’s free

rate than earlier-generation blenders,”

charcoal and Sahara – in addition to

of any highs and lows. Moreover, its tex-

concludes Small.

numerous other colour options and can

tured finish ensures that it’s non-slippery

also be ordered in bush-hammered and

when wet,” says Small.

(Above): Santigo is a new paving block produced by Aveng Infraset with an attractive textured finish.

DEMOULDING MADE EASIER CMA member Chryso has launched a com-

little odour. The range even includes a

plete range of technologically advanced

vegetable-based, environmentally friendly

releasing agents for use in the construc-

release agent which is biodegradable and

tion and precast concrete industries.

non-toxic, making it safe to use in confined

According to Hannes Engelbrecht,

applications such as mining and tunneling,

general manager: inland at Chryso South-

or any other poorly ventilated area.

ern Africa, getting the best results requires choosing the appropriate release

Wide range

agent, as there are specific formulations

Reducing blow holes is also possible, with

for all options, including timber formwork,

low-viscosity oil lowering the surface (Above): Releasing agents are a valuable part of any construction project, ensuring that concrete does not stick to formwork or moulds.

tension against the sides of moulds

(Below): Hannes Engelbrecht, general manager: inland at Chryso Southern Africa.

is designed for dry precast spun pipe

says Engelbrecht, “as the cost is rela-

quality of the Chryso Dem range ensures

release of dry concretes which have been

tively low, compared with the value of

that there’s no adverse effect on the

exposed to the high temperatures of

the formwork or mould. The Chryso Dem

adhesion of subsequent finishes and

steam-curing. Others are mineral-based

range ensures easy, clean release of the

coatings,” says Engelbrecht. “This allows

release agents suitable for all types of

formwork or mould from the concrete,

plaster, paint or other coatings to

without damaging either.”

be applied to the concrete with no

“The Chryso Dem range is a

associated problems; the release

fundamental change for an industry

Surface finishing

agents are also water-repellent, so

accustomed to a one-size-fits-all

The products reduce the likelihood of any

they aren’t affected by rain.”

man-made formwork and decorative concrete, as well as wet or dry precast.

“It’s false economy to simply use the cheapest releasing agent available,”

imperfections and surface damage to the

These products do not have any

and allowing air bubbles to escape. It production, with the added benefit of the

formwork on site.

approach when it comes to release agents,” says Engelbrecht.

concrete, such as blow holes, creating

negative effect on the hydra-

more durable and attractive concrete

tion of concrete as it cures

among user s, who’ll

surfaces.

and they are inoffensive to

now start expecting

apply, as they have very

better results.”

“It’s important to remember that the

PRECAST | ISSUE TWO | 2017

“It’s also raising the bar

PRODUCTS

CMA member Aveng Infraset has intro-

17

PRODUCTS

BIRKENMAYER EIRICH ANNOUNCES HB RANGE OF CONCRETE MASONRY MANUFACTURING MACHINES

19

CMA member H Birkenmayer started impor ting V ibr o Block brick-mak ing machines from Germany in 1955 and exhibited a small Vibro Block machine at the Rand Easter Show of that year. Such was the success of these machines that it soon afterwards obtained permission to manufacture locally.

Thus, the VB brand was established

tinue the VB logo, replacing it with HB,

in the VB1 machine, followed soon after

identifying its machines more closely with

by the VB2 – and in the 1970s, the VB4.

H Birkenmayer. Thus, the HB14, HB20,

Subsequently, the VB machines were

HB33, HB48 and HB68 now comprise a

copied by other manufacturers and these

comprehensive range of machines to suit

machines also carried the VB designation.

every application.

Over the years, this has caused a great

Over the past decade, upgrades to the

deal of confusion in the marketplace,

previous machine designs have been ongo-

with many customers believing that the

ing, mostly driven by developments and

copied machines were actually Birken-

performance offered in the more costly

mayer originals.

imported machines, but always mindful

Imitation might well be the sincerest

of the necessity to relate closely to the

form of flattery, but it can be a problem

requirements of the local market and,

commercially. In 2005, the management

indeed, many others less sophisticated

team at Birkenmayer decided to discon-

than those of Europe and North America.

The recent acquisition of 100% of H Birkenmayer by the worldwide Eirich

PRECAST | ISSUE TWO | 2017

or projected future expectations.

Group is the latest turn of fortune in

While the HB68, for instance, can be

an already eventful 65-year history. The

offered with unique tamper locking, so-

latest HB68 machine is manufactured

phisticated feed box features, any pallet

specifically to customer requirements;

and product size capability and advanced

this model offers many of the features

electronics, the fundamental machine is

of imported machines, while retaining the

the solid VB6, so well-accepted in the

original Vibro Block philosophies which

marketplace and still built to the exacting

have contributed to the quality Birken-

Vibro Block policy of Quality First.

mayer customers have learnt to expect.

Pairing with the popular Eirich In-

In keeping with the Eirich Group policy,

tensive mixer RV19, this combination

customer requirements come first. Ma-

offers an incomparable performance and

chines are offered to suit the application,

quality-to-cost ratio.

PRODUCTS 20

ZIMBABWE PIPE MANUFACTURER UPGRADES EQUIPMENT

Successful installation

to market through the company’s own

”It assisted in the design of the batch-

The commissioning of a new high-tech

fleet of trucks and delivered directly to

ing plant, the design of the building, the

pipe and manhole ring plant in Harare is

clients’ sites.

logistics inside the building, as well as

Since commissioning, the plant has met all production requirements and produced the new range of products, which dovetail perfectly with the company’s range of existing products and services.

These include the manufacture, supply and support of a wide range of precast

of information in the design phase of the

concrete products, which are brought

whole plant.

ensuring that technologically advanced,

The company is also able to provide

the outside logistics around incoming

high-quality products are available in

high-level technical advice in support

materials and outgoing products. The co-

Zimbabwe’s capital city.

of the products, as well as providing

operation with HawkeyePedershaab has

Acsend Concrete’s investment in a

skilled manpower to ensure products are

given me a state-of-the-art production

VIHY Multicast SCV 120 production plant

installed correctly on site. “Since instal-

plant that can supply current demand

from CMA member HawkeyePedershaab

lation, our new machine has significantly

and can easily be geared to supply future

enables the manufacturer to reliably

enhanced product quality and ensures

needs. I firmly believe that a dependable

produce a range of high-quality rings and

complete consistency with required

precast product has its roots deeply

short pipes for infrastructural projects

specifications.

embedded in an equally reliable production

within the region. In keeping with market

“In addition, the VIHY Multicast SCV

demands for consistent quality, the new

120, with its unique vertical vibration

equipment also offers the best possible

system, gives us flexibility and versatility

production and material-efficiency for the

to introduce all-new products to the Zim-

manufacturer to produce cost-effective

babwean market – as seen on my tours

precast solutions.

of Scandinavia. These will be introduced

According to Acsend Concrete owner and managing director, Antony Benesi, the

plant,” he says.

(Top): Acsend Concrete managing director Antony Benesi.

(Above): VIHY Multicast SCV 120 is a versatile vibration machine for the production of manholes and short pipes up to 1 200mm diameter.

in months to come, to add value to our local market,” says Benesi.

expansion project followed months of inves-

Plant description HawkeyePedershaab’s scope

tigation on his part as he travelled exten-

Close co-operation

of supply:

sively to study best practices and find the

He explains that Acsend Concrete and

– VIHY Multicast SCV 120.

most suitable equipment for his company’s

HawkeyePedershaab worked closely

– Mould equipment for

requirements. These travels culminated in

together throughout the whole pro-

Scandinavia, where he was inspired by local

ject. “I knew the HawkeyePedershaab

– Mould equipment for

producers who had embraced technology

service ethic and its machines from

from HawkeyePedershaab to produce

previous experience, so I had no doubt

– Automatic concrete batching

cost-effective and high-quality prod-

it could supply the equipment I needed.

ucts. This became the inspiration for the

But, equally important, it was a very

– Concrete laboratory equipment.

Harare-based plant’s upgrade.

valuable partner and an incredible source

450-1 200mm pipes, L=1,25m.

900-1 050mm manhole rings. and mixing plant.

PRECAST | ISSUE TWO | 2017

PRODUCTS

LONG-LASTING PAVERS In 1978, the Aggeneys mining township

“That was 39 years ago and the roads

was developed in the Northern Cape by

and houses are still in perfect condition,

the then Black Mountain Group. Housing

even though traffic throughput has been

and roadways were built for the group’s

at a far greater speed than the original

employees and local residents. Techni-

roadways were designed for,” says Tony

crete, then known as Concor Precast,

van der Berg, technical executive at the

operated two block manufacturing plants

IS Group.

21 (Above): Technicrete’s Olifantsfontein factory.

adjacent to Aggeneys, enabling it to

“We visited Aggeneys 15 years ago

produce the then newly-designed Zig-Zag

with engineers from the Black Mountain

gies and equipment in the manufacture of

block pavers for the project.

Group who confirmed that they’d con-

our Technicrete concrete products and

ducted no maintenance whatsoever since

these, too, will stand the test of time.

we supplied the new Zig-Zag product

Our expertise in concrete technology is

in 1978. We’d also originally supplied a

well documented not only for standard

number of black hollow products for the

products, but for customer-specific re-

housing project and, when visiting earlier

quirements as well,” says Van der Berg.

(Above): Manufacture of DZZ pavers.

this year, we found they still have a good

Since 1978, Technicrete has intro-

surface and appearance – testimony to

duced Double Zig-Zag (DZZ) interlocking

our manufacturing and design capabili-

pavers, which offer the same longevity

ties and a real commendation for the use

and cost-effectiveness through their

of concrete in order to obtain a longer

continuous, hard-wearing surface over-

lifespan for such applications.

lay. They are particularly suited for areas

“Originally, we manufactured our Zig-

of heavy traffic such as municipal parking

Zag product with a VB4-sized Schlosser

areas, petrol station forecourts, indus-

machine and a single Besser machine. To-

trial and factory roads, suburban streets

day we use far more advanced technolo-

and domestic driveways.

CASTLE BOTTOM KERB INNOVATION TROPHY WINNER - CMA AWARDS FOR EXCELLENCE 2016

Advantages of Castle Bottom Kerbs compared to conventional kerbs: 1. More load points help the Castle Bottom Kerb sink into the screed, creating much better adhesion in all directions.

2. Eliminates air pockets in the screed which could create weaknesses under the kerb after installation.

Castle Bottom Kerb

E+I 4694

www.bosun.co.za Tel 011 310 1176 info@bosun.co.za

Conventional Kerb

PRODUCTS 24

ENGINEERED SOLUTIONS FOR SOUGHTAFTER LUXURY APARTMENTS Elematic South Africa’s (ESA’s) highquality precast hollow core concrete slabs and top-notch service on the Carlswald Luxury Apartments development in Midrand secured the company a good pipeline of work from the estate’s

(Above and right): The Carlswald Luxury Apartments used hollow core slabs from Elematic.

developer, Century Property Develop-

hall, a clubhouse, a swimming pool, braai

slabs were selected primarily because of

ments, going forward.

facilities, a tennis court with pavilion,

the speed they offer in comparison with

The Carlswald Luxury Apartments

children’s play areas, outdoor gyms,

cast-in-situ concrete slabs. Overall, the

project was no small undertaking. The

a skate park, a bird hide and a Spark

construction team was able to complete

470 units, configured in 86 blocks, were

School for the children of residents.

approximately 40 units a month on

developed and built in a single phase

ESA supplied all the precast hollow

average – an achievement which would

by Century Proper ty Developments

core concrete slabs for the project, sup-

not have been possible without careful

between May 2015 and October 2016.

plying about 55 000m2 in total. Hendry

planning, co-ordination and teamwork.

The development also includes a variety

Brand of Century Property Develop-

In that respect, Brand is highly com-

of amenities such as a multi-purpose

ments explains that precast hollow core

plimentary about the service Century

service and our working relationship,

tions and to value-engineer each project

ESA. “To begin with, there were a num-

we really do get the whole package from

with our clients,” notes Craig Webber,

ber of different designs that had to be

ESA,” he says.

director at ESA. “We also try to improve

catered for because of the various differ-

“We need a high-quality product be-

continually on what we’ve done before.”

ent apartment and block configurations.

cause we want longevity in our buildings,

This meeting of minds has resulted in

We used all the different thicknesses of

especially since they are for the rental

a good working relationship with Cen-

concrete slabs available – sometimes we

market. At the same time, we also need

tury Property Developments, which has

even used them all on a single floor,” he

awarded ESA a number of other con-

notes. He goes on to say that even before

tracts subsequent to this one. “There

the project broke ground, the Century

are benefits to working with the same

Property Developments team, including

contractors and suppliers if we can,” com-

its in-house architects, sat with the ESA

ments Brand. “The ESA team know what

team to look at ways of optimising the

questions to ask, they know how we work

structures for economies of scale, and

and they’re extremely thorough. Like us,

to value-engineer for cost-effectiveness.

they take pride in their work. We also find

“We worked well together because we

that working with people we know means

both like precision, and we like to have

we don’t have to go through a process of

things well planned out in advance,” he

trial and error with a new contractor for

comments.

25

every project, because that can result in

There was an ESA team on site al-

to find ways of optimising our costs,

most constantly for the duration of the

which can escalate quickly on a project

The Carlswald Luxury Apartments

project, measuring up and installing the

of this size,” he continues. ESA’s willing-

development has certainly been a suc-

slabs, which were on the critical path for

ness to explore options with the client,

cess, with only a few units left to let at

project completion. Brand reports that

while maintaining high attention to detail

the time of writing. With one-, two- and

Century Property Developments has

and not compromising on product quality,

three-bedroom apartments available,

been very pleased with both the quality

helped ensure the successful delivery of

ranging from 53-113m 2, these luxury

of the slabs and the service received

Carlswald Luxury Apartments.

rental units in a secure lifestyle estate

from ESA. “In terms of price, quality,

V I H Y

PRODUCTS

Property Development received from

“We make every effort to explore op-

costly mistakes.”

have become extremely popular.

M a s t e r f l e x

The Masterflex machine is an allround machine for the production of concrete pipes as well as concrete manholes

• All-round machine for vertical cast concrete pipes and manholes • Easy to operate • VIHY core vibration for maximum compaction and rugged performance • Automatic production cycle giving high output with minimum amount of labor • No overhead crane required and no specific requirements for building • 24/7 after sales and service programme for every customer proud member of CMA

PRECAST | ISSUE TWO | 2017

European Headquarters Saltumvej 25 9700 Bronderslev Denmark

North American Headquarters 506 S. Wapello St. Mediapolis, Iowa 52637 USA

www.hpct.com

PRODUCTS 27

12M-HIGH RETAINING WALL SYSTEM BUILT WITH SPECIALIST GEOTECHNICAL ENGINEERING Limited space and precipitous slopes

with 300kN tie-back anchorages and con-

called for specialist geotechnical engi-

crete waler beams. Geofabric reinforce-

neering in the construction of some of

ment was not an option in this instance,

the concrete block wall structures in

due to the space between the retaining

Bakoven on Cape Town’s Atlantic sea-

wall block facing and the embankment

board. The walls were built to retain a

face being only 300mm. Steel-reinforced,

the backyard walls is 12,4m. The lower

steep granite embankment which was

the waler beams measured 350mm thick

wall is the highest, at 5,6m. The middle

cut to create a building platform for the

and about 1 000mm high. They were

wall tops 3,7m and the upper wall 3,1m.

construction of a luxury six-storey apart-

constructed on the upper and lower wall

Each of the three main walls was built at

ment block offering spectacular views

sections and spanned the full width of

an angle of 75˚. There are two narrow

of the Atlantic and the Twelve Apostles

the embankment face.

terraces between the lower and middle

mountain range.

Further reinforcement was achieved

wall and the middle and upper wall.

Apar t from the sea-facing front

by filling the blockwork in the lower half

A sophisticated sub-surface drain-

elevation, the remainder of the building

of each of the three main concrete block

age system was built into the design to

is enveloped in a cocoon-like concrete

walls with steel-reinforced concrete.

handle the percolation of water from the

block wall structure of varying heights

Free-draining sand was used to fill the

slope and to prevent the build-up of pore

and angles. The walls were designed by

space between the blocks and the em-

pressure. In addition, rainwater flowing

structural engineer, Fred Laker, with

bankment. The total combined height of

off the mountain slope is captured in a

geotechnical engineering input from

stone-filled trapezoidal concrete channel

Kantey & Templer Consulting Engineers

which drains away from the wall into the

on the principal retaining components

stormwater drainage system. Perforated

at the rear of the property. All the walls

100mm pipes were installed at the bot-

were built by Dassenberg Retaining using

tom of the fill material behind each wall.

L12 retaining wall blocks supplied by CMA

These drain into core drain pipes (gulleys)

member, Terraforce.

which, in turn, drain into stormwater

Geotechnical site inspections and

pipes. The stormwater pipes run under

a detailed slope stability analysis con-

the building and drain into a silt trap, which

ducted by Kantey & Templer revealed

then flows into municipal drainage.

that the bulk of the materials exposed

Fire escape staircases on each side

in the cut face took the form of deeply

of the property were built as part of the

weathered granites. It was determined

retaining wall structures using Terra-

that if left unsupported, parts of the

force’s 4x4 Step blocks.

embankment could be prone to instability during periods of high rainfall.

Following an assessment of various support options, Kantey & Templer recommended that two of the three main rear concrete block walls be provided

PRECAST | ISSUE TWO | 2017

(Top): Terraced concrete block walls built with Terraforce L12 blocks.

(Above): Tie-back anchorage on the upper waler beam.

(Left): One of the fire escape staircases built with Terraforce 4x4 Step blocks.

TECHNICAL 28

UNDERSTANDING THE

BASICS OF PAVING Manufacturers can play a role by raising awareness and sharing the basics of paving with installers who buy their products. The following article is based on the official SANS 1200MJ standards for paving installation in SA. The aim is to explain the flexible installation of segmented block paving in simple language to share with customers and installers of precast concrete pavers.

All too often paving projects fail because

the earth after excavation. If a plate

of poor installation, rather than the qual-

compactor is used, ensure its weight

ity of the pavers used. Sadly, manufac-

is at least 75kg.

turers’ reputations are on the line and

• Install a sub-base of 150mm with G5

can be incorrectly tarnished in the event

of a failure.

• Compact the sub-base with a roller

or similar material.

“Many paving failures occur due to ingress of water into the earthworks beneath the paving.”

It is worth noting that the entire pro-

or plate compactor weighing at least

cess – from initial earthworks, levelling

75kg. Compacting passes will be

and compaction to the design of various

determined by the type of machine

under-courses, pavers and finishes –

and its weight. Various passes should

tations or construct falls. Remember,

requires meticulous attention to detail

be made.

a fall of 2% is recommended in one di-

and needs to be done correctly to ensure

• Do not attempt to compact layers

rection (transverse) and 1% in another

the overall success of the project.

thicker than 150mm. It will not com-

(longitudinal).

pact sufficiently.

Also, paving should further be laid

Earthworks

• The sub-base is the foundation layer

proud of (ie 5-10mm higher than) drains

For commercial projects, bulk earth-

of the paving. It should be smooth,

or channels and sub-soil drainage needs

works are generally done by the main

level and the correct falls should be

to be installed when there is evidence of

contractor, while the laying of paving is

achieved with this material.

high levels of underground water. Drain-

left for a specialised paving contractor.

• Do not install plastic sheeting beneath

age channels and underground drainage

However, where earthworks are not

paving. Plastic sheets negatively

pipes should be installed in certain areas

done by a specialised contractor, the

affect the structural integrity of pav-

like low points in steep driveways, around

following sub-base and soil preparation

ing. They also do not prevent the

downpipes, etc. Carefully consider the

should be done:

growth of weed, as these grow from

natural land, walls and buildings when

• Set out the area to be paved and

the top and not through the paving.

designing a drainage plan.

excavate to a depth of approximately

250mm. (This should allow for a sub-

Drainage

Handling

base of 150mm, together with the

Consider drainage carefully. Many pav-

Pavers are fragile. They could chip and

thickness of pavers and bedding mate-

ing failures occur due to ingress of

break, if not handled with care.

rial used.)

water into the earthworks beneath

• Move pavers by means of special paver

• All tree roots and other plant matter

the paving. Construct the necessary

carts or pack them in wheelbarrows

gradients in your foundation layer and

and unpack them one by one.

do not use bedding sand to fill up inden-

• Never throw pavers in wheelbarrows

should be removed.

• Preferably use a roller to compact

PRECAST | ISSUE TWO | 2017

or front-end loaders and tip them at

sible. Ensure that the concrete beds

• Creating edge restraints by digging

the destination.

also retain the layers underneath the

a little trench on an edge after paving

• There will be slight variances in colour

paving. Therefore, bed-edge course

has been installed, then filling it with

between different batches and even

pavers on 75mm-thick concrete and

in-situ concrete and trowelling it down

packs of paving from any paving manu-

haunch at least half their height at

will definitely fail within a few months.

facturer anywhere in the world. It is

the back of the paver with concrete

therefore advisable to draw and install

at least 75mm wide. This will create a

Bedding

pavers from different packs during

solid concrete block that will not move.

• Well-draining sand containing no clay

installation to avoid a patchy finish.

• Use a moist concrete mix of four

and very little fines should be used for

parts sand, two parts stone and one

bedding.

Edge restraints

part cement to construct the bedding

• Please see the grading analysis for

Edge restraints prevent pavers from

and haunching of edge courses.

creeping. When pavers move horizontally,

• Experience has shown that the best

1200MJ (Table 1.1).

grouting material between them can be

edge restraints are kerbs. For resi-

• Do not mix cement with bedding sand,

lost and the paved area will fail completely.

dential and pedestrian applications,

• Edge restraints should preferably be

garden kerbs are suitable. Kerbs

• Bedding sand should be moist (not

installed before the paving.

bedding sand as specified by SANS

unless specified by an engineer.

should be bedded and haunched in

saturated with water) when bedding

• The earth preparation should extend

the same way as edge course pavers,

pavers. The sand should contain 4-8%

described above.

moisture.

to the rear face (outer side) of edge

restraints.

• On large paved areas and paving on

Tip: If you squeeze a handful of sand, it

• Edge restraints could be kerbs or

steep slopes, additional restraints

should compact to a ball, but no water

in the form of edge beams might be

should escape between your fingers.

• Bed-edge restraints in concrete and

required. Please refer to the CMA

• The sand bed must be laid slightly in

guidelines for steep slopes.

pavers/copings bedded in concrete. haunch them with concrete, if pos-

PRECAST | ISSUE TWO | 2017

advance of the placement of the units,

TECHNICAL

29

but only to the extent that the par-

that compaction should be done at

pavers, which prevents sagging and creep-

ticular area of paving can be com-

least once a day and more often when

ing. It also distributes loads to the layers

pleted within hours on the same day.

it is very hot.

underneath.

With the sun baking down, it should be

• A plate compactor should be used,

• Jointing sand must pass a 1,18mm

limited to a few hours at a time and

but it is recommended that a piece of

sieve and should contain 10-50%

its moisture content should be con-

rubber conveyor belting or special

material that passes a 0,075mm sieve.

tinuously assessed on site.

cover be attached to the base when

• Plaster sand is generally used for

• When bedding sand becomes dry, it

installing pavers with special surface

should be raked back into a heap,

textures.

moistened and spread out again.

Do not lay conveyor belting on the pav-

paving grouting in inland areas.

Tip: Use light-coloured plaster sand rather than red sand. Red plaster sand might

ers and compact on it, as this will absorb

stain your paving.

Nominal sieve size (mm)

% passing

the forces and pavers will not compact

• Sand must be bone-dry and swept

9,52

100

well enough.

• A roller could also be used to achieve

• Sweep diagonally across pavers and

levelling. Ensure the roller’s vibration

is switched off when this method is

• Go back and forth until all joints are

into joints.

4,75

95-100

2,36

80-100

1,18

50-85

preferred.

0,600

25-60

• Check and straighten lines and remove

• Do not use water to wash in sand

0,300

10-30

damaged pavers after the first plate

compaction. Use an alignment tool in

• Do not use a mixture of dry sand and

0,150

5-15

order to align and “tighten” pavers.

cement and then sprinkle water on it

0,075

0-10

• Do not compact closer than 1m of any

to hydrate. The cement left on pavers

will stain the pavers.

Table 1.1

free edge.

not along the “lines”. completely filled. between the pavers.

• Temporary edge restraints should be

• The CMA advises against using a

NB: The principle is to ensure you lay

used across the front laying edge

cement slurry to sweep into joints

pavers on a bed of moist sand. Moist

when installation is to be continued

between pavers. It might stain your

bedding sand will allow pavers to “bed in”.

the following day.

pavers and cause picture framing,

This is crucial to create a smooth, even

Tip: When this happens, remove the first

where pavers absorb moisture from

paved surface.

two or three rows of pavers when you

the slurry. This phenomenon creates

• Bedding sand should be 25-35mm in

start the next morning and re-pack. These

permanent white stains on the border

its compacted state. To achieve this,

pavers will have moved during the night,

of the pavers.

it should be screeded to a thickness

opening larger gaps than required.

of 30-40mm, which will then compact

to the correct thickness once pavers

Cutting

Vibrate sand on pavers in order to com-

are installed.

Precision cutting ensures a neat instal-

pletely fill joints between the pavers.

• Bedding sand should be screeded with

lation without movement and the loss of

• Use a large plate compactor with a

a straight edge (like a straight plank

grouting.

rubber mat fixed to the base plate,

or similar), using rails in order to

• Whole units must be laid first. Pre-

where applicable.

achieve the correct thickness.

cisely cut pieces should then be fit-

• Alternatively, use a roller with vibra-

Second compaction

The CMA does not recommend screed-

ted into gaps which are too small to

ing freehand in a circular motion, with-

lay complete pavers in, such as those

• Sweep more sand into the joints as

tion switched off.

out rails.

which are close to edges and around

sand settles in them.

manholes.

Critical maintenance: Sweep additional

Laying and setting out

• Mark and cut one paver at a time

sand into the paving joints after two weeks,

• Lines must be set up at right angles

using a block cutter. An angle grinder

two months and thereafter as needed, or at

to each other to control the alignment

or masonry saw with diamond-tipped

least once a year before the rainy season.

of the pavers.

blades can also be used.

• In areas with a high risk of sand wash-

• Align paving in a right angle with buildings.

• Do not use tiny cut pieces. Rather

• Joint widths of flexible installed pavers

use a 2 /3 and ½ paver in combination

• P a v er s sh o ul d n o t b e r em o v e d /

ing out, grouting sand could be stabilised.

instead of a full paver and a small bit,

replaced once jointing sand and the

• Most pavers in SA have spacer nibs

for instance.

final compaction have been done.

• Do not cut on paving already installed.

must be 2-6mm. to act as spacing guides when installing.

Fine concrete dust caused by cutting

Efflorescence

First compaction

will cause stains.

Because there are minerals and moisture

The first compaction levels the pavers.

• Always wear a dust mask, gloves and

in the soil and material we use to manu-

• Compact pavers in sections once they

facture pavers, paving might be affected

goggles. Do not cut near other people.

by efflorescence in its lifetime. It is a

are laid.

• Bedding sand must be moist when the

Grouting

natural, phenomenon which will disappear

Jointing sand creates interlock between

in time.

compaction takes place. This means

PRECAST | ISSUE TWO | 2017

TECHNICAL

31

TECHNICAL 32

MAKING SAFETY A PRIORITY Health and safety representatives in the concrete manufacturing industry are not a luxury. Rather, every company employing more than 20 staff must appoint one, in strict accordance with the law. In this, the fourth in a series of articles focusing on safety matters affecting the concrete manufacturing industry, well-known veteran health and safety expert, Oom Callie Calitz of OHS Consultants, looks at the appointment of health and safety representatives and their function in the workplace.

According to the law, every employer

(e) Facilities, training and assistance that

who has more than 20 employees in his

employment at any workplace

must be provided to a health and safety representative.

All the activities in connection with the designation, functions and training of health and safety representatives

shall, within f our months

Provided that there is no

shall be performed during ordinary work-

after commencing business,

registered trade union, the

ing hours, and any time reasonably spent

or from such time as the

employer shall consult with

by an employee in this regard shall for

number of employees exceeds

the employee representa-

all purposes be deemed to be time

20, designate a health and

tives in order to conclude an

spent by him in carrying out his duties

safety representative for a

agreement.

as an employee.

workplace, or for different

Correct appointment

Duties and care

sections thereof.

Only those employees em-

(A) A health and safety representative

specific period of time for the

Negotiations and consultation before

ployed in a full-time capacity at a specific

may perform the following functions in

designation of health and safety repre-

workplace, and who are acquainted with

respect of the workplace or section

sentatives:

conditions and activities in that workplace

of the workplace for which he has been

(1) The employer shall, in any workplace

or section thereof, shall be eligible for

designated:

where there must be a health and

designation as health and safety repre-

(1) Review the effectiveness of health and

safety representative, meet with the

sentatives for that workplace or section.

registered trade unions of the work-

The number of health and safety rep-

place in order to consult or bargain

resentatives for a workplace or section

in good faith and conclude an agree-

thereof shall, in the case of shops and

(3) In collaboration with his employer,

ment concerning the:

safety measures.

(2) Identify potential hazards and potential major incidents at the workplace.

offices, be at least one health and safety

examine the causes of incidents at

(a) Nomination and election of health and

representatives for every 100 employ-

the workplace.

ees, or part thereof and in the case of

(4) Investigate complaints by any em-

(b) Terms of office (the period of time

all other workplaces, at least one health

ployee relating to that employee’s

for which they are elected) and the

and safety representative for every 50

health or safety at work.

circumstances and prescribed manner

employees, or part thereof.

(5) Make representations to the employer

in which they may be removed as

If an inspector of labour is of the

or a health and safety committee on

health and safety representatives.

opinion that the number of health and

matters arising from the above para-

(c) Manner in which vacancies are to

safety representatives in the workplace

graphs, or where such representa-

is inadequate, he may give notice in writ-

tions are unsuccessful, to an inspec-

(d) Manner in which health and safety

ing directing the employer to designate

tor of labour.

representatives must perform their

the required number of employees to act

(6) Make representations to the employer

functions in terms of the Act.

as health and safety representatives.

safety representatives.

be filled.

on general matters af fecting the

PRECAST | ISSUE TWO | 2017

employer, who may be present during

the inspection.

“Manufacturers must have at least one health and safety representative for every 50 employees, or part thereof.”

(8) Participate in consultations with

inspectors at the workplace and

accompany inspectors on inspections

of the workplace.

(9) Receive information from inspectors,

as contemplated in section 36 of

the Act.

(B) A health and safety representative

shall, in respect of the workplace

or section of the workplace for which

(6) Participate in any health and safety

he/she has been designated, be en-

audit.

titled to:

(C) An employer shall provide such fac-

(1) Visit the site of an incident at all reason-

ilities, assistance and training as a

health and safety of employees at

able times and attend any inspection.

health and safety representative may

the workplace.

(2) Attend any investigation or formal

reasonably require and that have been

(7) Inspect the workplace, including any

agreed upon for the carrying out of

article, substance, plant, machinery

(3) Insofar as it is reasonable and nec-

his functions.

or health and safety equipment there-

essary for performing his functions,

(D) A health and safety representative

in, with a view to protecting the

inspect any document which the

shall not incur any civil liability by

health and safety of the employees,

employer is required to keep in terms

reason of the fact only that he failed

at such intervals, as may be agreed

of this Act.

to do anything which he may do or is

upon with the employer. The health and

(4) A ccompany an inspec tor on any

required to do in terms of this Act.

safety representative shall give rea-

inspection.

sonable notice of his attention to

(5) With the approval of the employer, be

Safety greetings!

carry out such an inspection to the

Oom Callie

inquiry held in terms of this Act.

accompanied by a technical advisor.

PRECAST TECHNOLOGY

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PRECAST ISSUE TWO www.sika.co.za

| 2017

TECHNICAL

33

TECHNICAL 34

COST-CUTTING LEADS TO CBR WA The past five years have seen an upward spike in concrete block retaining (CBR) wall failures. This concerning situation was further highlighted during the heavy rains around Gauteng in December 2016 and March 2017, with at least half a dozen significant failures. While heavy rains certainly exacerbate the problem, there appears to be a fairly regular stream of failed and collapsed CBR walls.

So why is there no consumer protest,

• They are highly suitable for greening

their CBR purchase decisions, irrespec-

especially when it involves huge expense,

and the growth of vegetation.

tive of whether a wall design satisfies

potential injury and even fatalities? Imag-

This is why CBR walling is often the

ine the outrage if the same frequency of

preferred retaining wall choice. Which is

sound engineering principles.

What should happen at the very

failure pertained to bridges and buildings,

as it should be, because if fundamental

outset of any CBR project with walls

the motor industry or any profession in

engineering principles were followed

higher than 2,5m is the appointment of

which essential engineering principles

in design and construction, CBR wall

an independent structural engineer to

required for the maintenance of accept-

failures would be lower than 0,2%.

take responsibility for the proper design

able standards of function, durability and

and construction of the wall. This involves

safety were disregarded.

striking a balance between best-practice

How has this situation been allowed to

engineering and cost, with the overrid-

happen? The answer, or rather answers,

ing aim of building a wall which will last

follows in this article based on an inter-

decades and longer.

view given to Precast’s coastal media

Once completed, the design should

representative, David Beer, by geotechin-

be submitted to a geotechnical engineer

cal engineer and MD of Verdicon Consult-

for review. And should the project prove

ing Engineers, Trevor Green and general

complex, due to considerations such as

manager of MVA Bricks, Vernan Small.

unstable soil conditions, unusually large

Many professionals involved with the

wall loadings or exceptionally high walls,

industry know what it takes to build a

a geotechnical engineer should be ap-

sound wall. Most of their clients do not,

pointed to handle the design.

or, if they do, are not inclined to involve themselves in the technical minutiae of their wall design. However, what all of them do know is that CBR walling offers

Corners cut (Above): An example of a well-constructed CBR wall.

Sadly, in the current South African construction environment, the ideal and

them substantial advantages, including

Moreover, if CBR wall clients followed

reality are light years apart. Most often,

the following:

the same rigorous approach to CBR wall

the client, be they the main contractor

• CBR walls remain the most economical

construction as they do in, say, rein-

on the overall project, a property devel-

way of building a retaining wall.

forced concrete and structural design,

oper or property owner, bypasses the

• The system offers ease and speed

there would be no need for this article.

structural engineer and calls for tenders

However, most do not. Instead, what

from CBR contractors. The contrac-

• CBR walls have the ability to follow

happens in the majority of cases is that

tor submits a “design and construct”

clients rely exclusively on price to make

proposal, where the design is either

of construction. any contour.

PRECAST | ISSUE TWO | 2017

ALL FAILURES prepared in-house or by an engineer

to take a long, hard look at the “design

employed by the contractor.

and construct� model and the practice

The pressure on the contractor and

of awarding work based purely on cost.

engineer to win the tender is immense,

When skimping first began, the ef-

with the result that engineering integrity

fects were not immediately apparent,

in wall design is steadily eroded. CBR wall

but over the years it has grown into large

clients, who have other priorities to deal

material deficiencies. One of the results

with, are generally unaware of this, which

is that clients now have unreasonable

is a significant factor in why so many

expectations about what a wall should

failures occur.

cost and are appointing contractors who

During the good times when there was

take chances on every job. Without real-

abundant work for all in SA, this “design

ising it, the client then assumes the risk.

and construct� model worked and stand-

What CBR contractors are tempted

ards were maintained. However, since

to do is assume that the most optimistic

2010, when demand for construction

scenario will apply to their wall and then

projects fell dramatically, CBR work has

prepare their tender submission accord-

become much harder to find, a situation

ingly. This is unrealistic. Geotechnical

which greatly increases the incentive for

information, ground water and loading

cost-cutting. And this is exactly what

conditions, both structural and traffic-

has happened. It began with small cuts,

based, have to be carefully evaluated.

but these have increased incrementally

One cannot simply assume that the site

to the point where some walls are barely

will remain dry and that perfect condi-

standing once the contractor leaves the

tions will prevail. Moreover, some fat

site. And those contractors who actu-

must be included in the design to allow for

ally do submit designs based on good

unknown factors, such as seismic events

engineering practice do not get the work.

(small earthquakes) and some ground water flow. Ground is a volatile medium and

Everyone’s problem

is highly variable. It doesn’t help to build

A tender only needs to be a few rand

a wall which is only 90% compliant. All

per square metres less to be won. The problem is that if a wall falls down, it is not only the contractor’s problem – it becomes the whole project’s problem and the entire professional team gets dragged into the mess. It involves damage to reputations and to adjacent properties, as well as expensive litigation, not to mention the cost of rebuilding the wall. Surely this is a compelling incentive

PRECAST | ISSUE TWO | 2017

G e n u i n e

c o m p e t i t i o n i s

good

for

the

c o n s u m e r Imitators are

NOT

TERRA FORCE

“Typically, the only solution for repairing collapsed walls is a rebuild.�

(Above, from left): Two examples of failed CBR walls; an example of a well-constructed CBR wall.

Find your nearest supplier www.terraforce.com

Te l : 0 2 1 4 6 5 1 9 0 7

TECHNICAL 36

walls above 2,5m should only be designed on the basis of a geotechnical report.

be removed lowers the cost of the wall.

It is imperative that the way work is

Good drainage, too, is absolutely criti-

tendered and awarded be reviewed be-

cal to the stability of a wall, as is the fill

cause the reputation of the entire CBR

Costly skimping

material behind the wall. The latter should

wall industry is at stake. This will have

Cost-cutting comes in many guises, but

comprise G7 or better and be properly

to be motivated by the clients, once they

all undermine the structural integrity and

compacted in 150mm layers and water

realise that saving a few rand on a retain-

safety of the walls. Cheaper and lighter

should always be drained as quickly as

ing wall is false economy – particularly

hollow blocks, for instance, might be used

possible. At a bare minimum, a circular

given that alternatives to CBR walls are

on a very high wall. This results in cracked

drain should be installed at the back of

so much more expensive.

blocks due to the large amounts of com-

the reinforced zone, with outlet pipes

Certainly, most of the designers who

pressive force exerted by high walls.

spaced every 5m or 6m. In cut-and-fill

work for CBR wall contractors would be

Alternatively, a block might not be made

walls, drainage at the bottom of the wall

happy for the model to change. At the very

with enough cement (ie sub-standard

should be supplemented so that any water

least, property-owners and developers

manufacture of the block itself).

which reaches the face drains speedily.

should be wary. They should not automati-

However, by far the most common

cally opt for the cheapest wall and need to

problem is skimping on the geosynthetic

Expensive solution

ensure that the contractors they appoint

reinforcing, either by reducing its depth

Typically, the only solution for repairing

are competent and experienced special-

and/or strength or by increasing the spac-

collapsed walls is a rebuild, because all

ists. A well-built wall costs a little more,

ing from, say, every third block to every

the other alternatives – such as piling,

but everyone gains in the long run.

fourth, the former being the most preva-

soil nails, anchors and grouting – are so

The Concrete Manufacturers’ As-

lent. In an ideal wall, the ratio of geofabric

specialised that they are more expensive

sociation NPC (CMA) has published two

wall height should be 70%, but over time

than rebuilding. The most cost-effective

brochures on CBR walling: a design manual

this ratio has slumped to as low as 50%

solution is to rebuild with a more ap-

and an installation manual. These should

in certain instances. Some contractors

propriate design, perhaps with additional

form part of any property developer’s

even use filter geosynthetics for reinforc-

drainage or better construction, or a

library and they are available from the

ing, which are almost useless. In cut-face

combination of all three. Better still would

CMA at nominal cost. Contact Henry

walls, where soil is removed and replaced,

be to design and construct the wall cor-

Cockroft on tel: 011 805 6742 or via

any reduction in the amount of material to

rectly in the first place.

email at: marketing@cma.org.za.

We are there when you learn

Need to conquer concrete? Our School of Concrete Technology offers special on-site and tailor-made courses to suit your requirements. Study concrete with us. www.theconcreteinstitute.org.za PRECAST | ISSUE TWO | 2017 +27 11 315 0300

PROJECTS 37

PRECAST CONCRETE MAXIMISES

PROPERTY INVESTMENT Situated a stone’s throw from Stellenbosch, Nooitgedacht Village is an upmarket estate which is being built with several precast concrete elements supplied by CMA member, TopFloor. When completed, it will comprise an exciting mix of residential, commercial and retail components which offer attractive, safe Cape winelands living.

With the retail and commercial elements

“Our aim is to take the hassle out of

yet to be built, the site currently com-

construction and get the developer and

prises several types of very attractive

the professional team onto their next site

residential property, including upmarket

as quickly as possible. For example, at

three- to five-bedroomed houses on

Nooitgedacht, we’ve been involved in the

freehold stands and a mix of sectional

primary and secondary engineering design

title units ranging from three-bedroomed

stages and are providing the cranes and

cluster houses to duplex units and one-

trucks to install the precast elements.

bedroomed apartments.

We’ve also spent a lot of time before and

construction, commercial, retail and, of

during construction liaising with the ar-

course, residential,” says Prinsloo.

One of the common factors linking all the units is that they are multi-storeyed

chitects and structural engineers.

TopFloor precast concrete is pro-

and are being built with TopFloor’s pre-

“Precast concrete construction is

duced in a controlled factory environment

stressed hollow-core slabs for the upper-

undoubtedly quick. Units are installed

and uses the latest computer-aided

level flooring, precast concrete beams

in a matter of hours, rather than the

designs. This guarantees a consistently

to support the slabs, precast concrete

weeks it takes for in-situ construction.

high level of quality which is very difficult

staircases and precast concrete lintels.

And in the case of upper-level flooring,

to achieve with in-situ construction.

precast hollow-core slabs allow other

Moreover, it is recyclable and can be

Free space

services, such as masonry, electrical and

used to produce concrete bricks and

According to TopFloor MD, Wessel Prins-

plumbing, to commence work as soon as

in road construction. Very little waste

loo, one of the major advantages of build-

they’re installed.

is produced in the production process

ing with precast is that it minimises on-

because all materials are used optimally.

site clutter and wastage, thus speeding

Speed of construction

up construction time immensely.

“Further time-savers are the smooth

construction of all types of buildings and

Precast concrete is safe for the

soffits of the slabs and rough finishes on

does not exude harmful substances into

their upper sides. This enables them to

the environment.

be painted without the need for skimming and makes screed bonding hassle-free.

Another advantage of using hollow-core flooring is its superior thermal and sound insulation properties.

“All types of property development lend themselves to precast concrete

PRECAST | ISSUE TWO | 2017

(Top, from left): Two semi-detached sectional title units; one of the freehold houses at Nooitgedacht Village.

(Above): One of the TopFloor precast concrete staircases at Nooitgedacht Village.

(Left): The smooth soffit finish of TopFloor’s hollow-core slabs creates an attractive ceiling in this Nooitgedacht Village house.

PROJECTS 39

“We opted for a demountable design

“The steel frame comprised vertical col-

because we have other medium-term

umns – mounted on concrete pad footings

development plans for this valuable Beach

– and steel cross-beams which supported

Rd stand which commands spectacular

the prestressed hollow-core slabs. The

views over Granger Bay,” says V& A

framework was reinforced with a minimum

development executive Martin Kearns.

of cross-bracing to provide as much car

“Given the demand for parking at the

space as possible. We achieved this by

Waterfront, it made sense to use the

installing additional reinforcing in the form

land productively in the interim, especially

of steel ‘ladder’ bracing at first-floor level

with a building which could be unbolted

along the full length of each elevation.”

and re-used elsewhere with minimal onsite demolition works.”

Hollow core

The concept of a demountable struc-

The parkade has been designed to accom-

ture was initiated by V&A’s development

modate a fourth parking level and to fa-

project manager, Niaz Ahmed, and was

cilitate this, the steel columns protrude

PRECAST TO BUILD MECCANOSTYLE V&A PARKADE

structurally developed by LH Consulting

above the third-level parking section. In

Engineers. MLB Architects converted

addition to supplying 8 800m² of pre-

the concept into blueprint and NMC

stressed hollow-core slabs each measur-

Construction was responsible for the

ing 7,5m x 120cm x 160mm for the two

construction and assembly work. Other

upper parking levels, Portland Hollowcore

members of the construction team in-

also supplied 16 precast staircases for

cluded BTKM Quantity Surveyors and

the building’s four stairwells.

SA’s first demountable parkade has been constructed at Cape Town’s V&A Waterfront. Providing the V&A with an additional 540 parking bays over three floors, the structure was erected using bolt-on steel frames supplied by Union Steel and prestressed hollow-core concrete slabs supplied by CMA member Portland Hollowcore.

PRECAST | ISSUE TWO | 2017

KLS Consulting Engineers.

A third precast element came in the form of exposed aggregate concrete

Steel replacement

block pavers, supplied by Inca Concrete

“The use of precast concrete slabs on

Products, which were used to create an

the upper two levels and on the inter-level

attractive surface on the ground-floor

vehicle ramps is what really made this

parking level. These, too, can be lifted

structure viable,” says Ahmed.

and relaid elsewhere. Although the Beach

“We could, of course, have relied solely

Rd parkade is classified as a temporary

on steel, but that would have rendered

structure, its steel and concrete mate-

the entire venture impracticable. Hollow-

rial mix means that it can enjoy the life-

core slabs not only offered re-usability,

span of a normal structure. And because

but – because they’re lighter than in-situ

it has no lateral walling to speak of, no

concrete – less steel was required for

mechanical ventilation is required.

the framework. Moreover, their ease and speed of installation using mobile cranes meant that this was a genuine fast-track project which was completed in time to alleviate an increased demand for parking over the festive season.

(Above, from top): The attractive façade of the V&A’s recently-constructed parkade showing the slat screening on one of the elevations, the precast staircase, some cross-bracing and the “ladder” bracing; prestressed hollow-core beams above and below and the “ladder” bracing seen on the left of the image; steel columns extend above the third level in preparation for the addition of a fourth level.

A strong foundation for infrastructure success

ADDING GRACE TO UPMARKET CAPE HOUSING DEVELOPMENT

Concrete roof tiles, manufactured by CMA member Marley Roof Tiles, are being used exclusively in the construction of Hillwood, a flagship residential estate currently under development by non-profit company Garden Cities (RF), in Cape Town’s northern suburb of Pinehurst.

Marley’s Spectrum Slate Double Roman Plus was selected for all the hipped roofs and its Antique Amber Double Roman tile was selected for the gable-to-gable roofs to enhance the French Provençal architectural theme of the development.

Scheduled for completion in October 2018, the houses are being built in three- and four-bedroom designs and sell from R2,35 million-R3,1 million. The project’s main contractor is Garden Cities’ construction arm, Pinelands Development Company.

I15457

Marley regional commercial director, Juliano Amodio, says that besides their obvious aesthetic attributes, concrete roof tiles come with several other benefits.

“They offer one of the most cost-effective roofing materials and are largely maintenance-free. They don’t need painting and don’t rust. They also have good thermal properties and don’t require as much insulation material as steel roofs do to meet legal thermal roofing requirements.”

(Top): Marley’s Antique Amber Double Roman tile was selected for the gable-to-gable roofs at Hillwood.

(Below): Marley’s Spectrum Slate Double Roman Plus tiles accentuate the French Provençal architectural theme at Hillwood.

ROCLA is South Africa’s leading manufacturer of pre-cast concrete products. Surpassing 100 years of product excellence, including pipes, culverts, manholes, poles, retaining walls, roadside furniture, sanitation and other related products within infrastructure development and related industries.

Visit us on www.rocla.co.za for our nationwide branches PRECAST | ISSUE TWO | 2017

The Concrete Institute (TCI) has announced

is widely regarded as the definitive

was first involved in the sixth edition

that Prof Mark Alexander, who at the end

handb ook on concr e te technolog y.

of the reference book in 1986. T CI

of 2015 retired from the Department of

“Mark’s been very involved in lecturing

is therefore proud to announce that

Civil Engineering at UCT, will edit the 10th

for the Advanced Concrete Technol-

Mark has agreed to edit the 10th edition

edition of the world-renowned “concrete

ogy course pr esented by the T CI’s

of Fulton’s, which we hope to publish in

bible”, Fulton’s Concrete Technology.

School of Concrete Technology since

2018,” says Perrie.

Bryan Perrie, managing director of

the early 1990s. He’s also been heavily

Alexander was chairman of the TCI’s

TCI, believes Alexander has all the cre-

involved in writing and reviewing chap-

forerunner, the Cement & Concrete In-

dentials for the new revision of what

ters of Fulton’s Concrete Technology and

stitute, from 2011-2013.

PROJECTS

LATEST REVISION OF “CONCRETE BIBLE”

41

PHOTO CORRECTION In the last issue of Precast, we presented an article titled Quality Pipes Required for New Project about Rocla’s successful supply of pipes for the Diepkloof Zones 5 and 6 project. It was a great story, but – to our embarrassment – we mistakenly used an unrelated piping photograph to illustrate it. We apologise for this and to ensure our readers get a good look at the pipes, we’ve included two photographs of

E+I 4533

the project in question.

0861 762 781 (Nationwide) www.smartstone.co.za

PROJECTS 42

PAVING ROADS IN OUTLYING AREAS Durability of roads, as well as reducing the environmental impact on surroundings and the creation of employment, were considerations for the awarding of some large-scale paving projects for CMA member Technicrete.

Among the most recent projects the

Good traction

company supplied was an environmentally

“The openings in each block and between

friendly road system designed to blend

blocks are sized to benefit from enough

with natural landscapes, while offering

vegetation growth to make the surface

suitable durability and traction for motor

appear ‘natural’, while still maintaining

vehicles at Du Pont Pioneer’s newly-built

structural integrity. Similarly, it’s a good

research facility at Delmas, Mpumalanga.

solution for Jeep track-type installations.”

Technicrete’s Armorflex system was

Michael Magner, director at Activate

specified by both the architects and

Architects, adds that the Du Pont

engineers for use on construction of the

research facility was built on farmland

new entrance road and was chosen due

and the product blended perfectly with

to the client’s requirement for a “green”

the rural setting, while providing an

road that could blend in with the natural

erosion-resistant roadway and keeping

surrounds of the facility, while offering

into long mats which can be anchored

traffic at a slower pace due to the slight

suitable durability to traffic loading and

into in-situ soil. This further assists

roughness of the finishes on the product.

environmental conditions, with an im-

with stabilisation of the blocks and road

The project entailed a 400m-long roadway

pressive final appearance. The project,

surface. The loose, but interlocking de-

and parking area for approximately 40

which commenced in January 2016, was

sign allows the concrete road surface

cars. “Armorflex and kerbs were chosen

completed at the end of January 2017.

to remain flexible to movements, elimi-

by the project’s structural/civil engineer,

“The Internationally Licensed Armor-

nating the cracking and spalling issues

who’s had prior successes with these

flex system is manufactured in SA by

that plague solid concrete surfaces,

product ranges on other applications.

Technicrete and is the only similar type

even when exposed to regular inclement

Good access to the specification team

system available locally. It has the facil-

weather,” says Justin Kretzmar, sales

at Technicrete for reliable supplier-based

ity to wire-tie adjacent blocks together

engineer for Technicrete.

technical input made a positive impact for

PRECAST | ISSUE TWO | 2017

PROJECTS

us on this project,” says Magner.

“Armorflex road product was easy to install and the cells, when seeded and filled with topsoil, will enhance the growth of grass. The very design of Armorflex enables roots to penetrate the geotextile below the blocks, which enhances anchorage of the installation,

43

giving a very secure and sturdy surface for vehicle traffic. On this project, the final appearance was very good and blended well with the natural rural aesthetics of the completed facility,” says Probuild’s site agent on the Du Pont Pioneer project, Mark Guthrie.

Moletjie Road In another equally impressive project, Limpopo’s Public Works & Infrastructure Department announced that R1,2 billion

regularity of the bus traffic.”

forces on this R2 million project with

had been earmarked for road refurbish-

The project consisted of a combina-

MacP Construction. Where heavy traf-

ment and maintenance to be rolled out

tion of 50mm Bond Bricks together with

fic is experienced, our Bond Brick paving

over the next three years. Included in this

kerbs, 60mm and 80mm Double Zig-Zag

blocks are perfect because of their well-

roll-out was maintenance to a section of

Grey pavers and kerbs. The Bond Brick

established reputation for longevity and

the Moletjie Road Project in Polokwane

is a traditional paver that offers econo-

quality, while still offering a good finish

that was to be upgraded from gravel

my and durability and is very well suited

aesthetically. We aim to ensure that all

to paving. Technicrete’s Bond Brick and

to commercial and domestic surfaces.

stock is supplied as per client require-

kerbs were selected for this project.

Mak ap ani Modip a, CE O o f MacP

ments and this was the case on the MoDurable solution

Construction, says: “There was no es-

“It’s been a preferred choice not only of

tablished pavement on this section of

local municipalities, but of private commer-

Moletjie Road – it was a gravel walkway

cial developments as well,” says Hendrik

that needed to be upgraded to a paved

Steenkamp, sales consultant for Techni-

surface. Included along this stretch of

crete ISG in Polokwane. “Our precast con-

walkway, a 1,3km bus stop had to be

crete kerbs are an ideal edge restraint in

accommodated in the construction. To

the construction of roads, kerb and gutter

do this, we chose the Technicrete Bond

systems. We can now also offer our Figure

Brick and kerb products for their dura-

C900 mountable kerb, which can be used

bility. This was a key factor for the bus

in traffic-calming measures.

stop development, due to the weight and

PRECAST | ISSUE TWO | 2017

“We were pleased to have joined

letjie Road Project,” says Steenkamp.

“The loose, but interlocking design allows the concrete road surface to remain flexible to movements.”

MEMBER LIST 44

PRODUCER MEMBERS A FICK SEMENT WERKE BK Tel: (022) 913 1921 PROVINCE/COUNTRY: WC PILLAR: PB AVENG INFRASET (PTY) LTD Tel: (011) 876 5500/872 1713 PROVINCE/COUNTRY: GAUTENG PILLAR: PB/PI BOSUN BRICK MIDRAND (PTY) LTD Tel: (011) 310 1176 PROVINCE/COUNTRY: GAUTENG PILLAR: PB/PI BOSUN BRICK BRITS (PTY) LTD Tel: (012) 250 1711 PROVINCE/COUNTRY: NW PILLAR: PB/PI BOSUN BRICK PORT ELIZABETH (PTY) LTD Tel: (041) 405 0100 PROVINCE/COUNTRY: EC PILLAR: PB PANDA (PTY) LTD Tel: (00267) 244 2107/8 PROVINCE/COUNTRY: BOTS PILLAR: PB/PI BRICKCAST INDUSTRIES CC Tel: (031) 507 5525 PROVINCE/COUNTRY: KZN PILLAR: PB/PI BANZI TRADE 31 (PTY) LTD T/A BRICKIT Tel: (011) 023 6708 PROVINCE/COUNTRY: GAUTENG PILLAR: PB/PI C.E.L. PAVING PRODUCTS (PTY) LTD Tel: (021) 905 5998 PROVINCE/COUNTRY: WC PILLAR: PI CEMBLOCKS (PTY) LTD Tel: (014) 538 0311 PROVINCE/COUNTRY: NW PILLAR: PB/PI CIVILWORKS (PTY) LTD REAL TIME INVESTMENTS Tel: (011) 903 7023 PROVINCE/COUNTRY: GAUTENG PILLAR: PB/PI CONCRETE UNITS (PTY) LTD Tel: (021) 386 1923 PROVINCE/COUNTRY: WC PILLAR: PB/PI CONCRETE UNITS (PTY) LTD Tel: (016) 362 2236 PROVINCE/COUNTRY: GAUTENG PILLAR: PB/PI CONFRAMAT (PTY) LTD Tel: (0861) 33 5599 PROVINCE/COUNTRY: GAUTENG PILLAR: PB/PI COROBRIK (PTY) LTD Tel: (031) 560 3111 PROVINCE/COUNTRY: KZN PILLAR: PI CORESLAB (PTY) LTD Tel: (087) 232 2462 PROVINCE/COUNTRY: LIMPOPO PILLAR: PB/PI DERANCO PRECAST (PTY) LTD Tel: (041) 463 3338 PROVINCE/COUNTRY: EC PILLAR: PB/PI EAGLE ROOF TILES (PTY) LTD Tel: (044) 874 0290 PROVINCE/COUNTRY: WC PILLAR: PB ECHO PRESTRESS (PTY) LTD Tel: (011) 589 8800/8899 PROVINCE/COUNTRY: GAUTENG PILLAR: PB ECHO FLOORS (PTY) LTD Tel: (011) 668 1900

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PLEASE NOTE: The above member list was correct at the time of going to print.

If your details have changed, please contact Rita at the CMA offices on tel: (011) 805 6742

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PI – Precast Infrastructure PB – Precast Building

PRECAST | ISSUE TWO | 2017

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COST SAVINGS WITH EIRICH RV19 INTENSIVE MIXER SAVINGS IN CEMENT, PIGMENTS, ENERGY, WATER AND REJECT RATES HAVE BEEN REPORTED FOR 30 YEARS. PRECISE BLENDING AND HOMOGENOUS MIXES ARE ACHIEVED WITH SHORT MIXING TIMES. CONCRETE QUALITY AND SURFACE FINISH SPECIFICATIONS RISE CONTINUOUSLY. THE EIRICH R-TYPE MIXER IS BEST SUITED TO THIS DEMANDING ENVIRONMENT.

EIRICH RV19 INTENSIVE MIXER: INCLINED PAN CREATES STRONG VERTICAL MIXING ACTION AGITATOR BLADES BREAK UP LUMPS AND DISTRIBUTE WATER WATER AND CEMENT IS DRAWN THROUGH THE MIX BY A VORTEX CREATED AT THE SHAFT COMBINED FLOOR AND WALL SCRAPER DIVERTS MATERIAL INTO THE PATH OF THE AGITATOR FLOOR SCRAPER ALSO ASSISTS WITH FAST DISCHARGE

H. Birkenmayer • Website: www.birkenmayer.co.za • Tel: +27 11 970 3880 • E-mail: sales@birkenmayer.co.za