Precast 2014

PRECAST VOLUME EIGHT ISSUE 1 • 2014

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contents

1

precast contents NEWS

32 TECHNICRETE RETAINING WALL

WITHSTANDS MAJOR FLOODS

2 OBITUARY - VICTOR BOARDMAN 4

CI RUNS ADVANCED CONCRETE COURSE

5

PMSA TO HOLD TRAINING WORKSHOPS

6

SIKA AG 2013 SALES EXCEED

CHF 5 BILLION FOR THE FIRST TIME

Member details 33 MEMBERS LIST

PRECAST VOLUME EIGHT ISSUE 1 • 2014

ARTICLES 8

STEADY AS SHE GOES – THE CMA

REPORTS BACK

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FACTORY INTO SHOWROOM

• Record retaining wall height

iatio

• Building practice antiquated

• Precast transforms factory into showroom

soc

10 POLISHED CONCRETE TRANSFORMS

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as

COVER STORY

ncrete

from Mapei

Two of four polished precast concrete columns which frame the entrance to CMA member, PMSA’s (Pan Mixers South Africa) new showroom in Jet Park, Gauteng.

Weighing roughly six tons apiece, the columns support part of the roof structure and curtain walling, and were cast on site with Lafarge’s Artevia decorative concrete before being lifted into position by crane. co

7 New concrete joint sealant

ON THE COVER

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Precast is the official journal of the Concrete Manufacturers Association (CMA) 16 Horn Street, Chloorkop, Kempton Park, 1620 PostNet Suite 8612, Private Bag X32, Kempton Park, 1620 Tel: +27 11 805 6742, Fax: +27 86 524 9216 E-mail: admin@cma.org.za, Website: www.cma.org.za

15 RECORD RETAINING-WALL HEIGHT

REACHED IN KZN

Publishers Isikhova Publishing & Communications

19 LOCAL BUILDING PRACTICE ANTIQUATED

PO Box 651793, Benmore, 2010, South Africa

Tel: +27 11 883 4627, Fax: +27 11 783 2677

AND EXPENSIVE

24 CMA MEMBERSHIP - EIGHT MORE

AND COUNTING

26 ALL SET FOR CEMENT-FREE CONCRETE

Website: www.isikhova.co.za

Publisher: Andrew Meyer Tel: +27 11 883 4627, Cell 082 456 5175 E-mail: andrewm@isikhova.co.za Editor: David Beer Tel: +27 11 478 0239, Fax: +27 11 678 0254 E-mail: david.bigsky@gmail.com

APPLICATIONS

Advertising: Linda Roberts

30 Fleet Management software

E-mail: precast@isikhova.co.za

boosts service levels of Ethiopian

Cement plant

30 PRECAST CONCRETE TOILETS FOR

AMATHOLE COMMunity

31 AFRISAM HELPS WINDFARM ACHIEVE

Tel: +27 11 883 4627

Design, layout and production: Joanne Brook Tel: +27 11 883 4627 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 he, 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.

FAST TURNAROUND times

PRECAST VOLUME 8 • ISSUE 1 • 2014

2

NEWS

OBITUARY VICTOR BOARDMAN Victor Boardman, for many years a respected and wellknown name in the South African construction industry, died suddenly in January.

Boardman, 50, was technical sales consultant at Chryso Southern Africa’s Gauteng regional office at the time of his death. He joined Chryso SA in 2008 and he spearheaded the launch of the Pareflo range, the group’s silicone water repellant which eliminates efflorescence in concrete blocks, bricks and pavers. He also provided invaluable advice on a wide variety of lightweight precast concrete matters.

A Benoni resident, Boardman’s career included management posts at Concor Ready Mix, Brownbuilt Metal Section, Constantia Echo, and Watson Concrete Products, and he was also a director of Inca Concrete Products, part of the Murray & Roberts Group. His duties for M&R included controlling on-site concrete batching operations.

Armand van Vuuren, Chryso SA’s commercial manager exports, says Victor Boardman was undoubtedly one of SA’s top authorities on lightweight precast concrete.

“His experience and commitment to duty are rarely found.

Victor won the respect of clients, not only in South Africa but within the entire African continent. He will be sorely missed by Chryso SA and our clientele.”

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PREC AST VOLUME

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E 1 • 2014

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Contact Linda Roberts for more information m

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• Build ing prac • Prec tice antiq ast tran uated • Reco sform s facto rd reta ry into ining wall show heigh room t

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Tel: 083 626 8814

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E-mail: precast@isikhova.co.za

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the cma – QUALITY CAST IN CONCRETE

PRECAST VOLUME 8 • ISSUE 1 • 2014

4

NEWS

The Concrete Institute’s 2014 ACT students pictured just after the start of their intensive tuition. From left (seated in front): Reuben Jonas, Gary Cronk, Gary Theodosiou (The Concrete Institute lecturer), and Zintle Khuzway. At the back: Sudir Mannengote (from Qatar), Garth McMillan, Warwick Railton, Bheki Makhathani, Darren Hoft, John Wilkins, Sibusiso Hlatshwayo, Revo van Zyl, Gerhard Woschitz, Sean van der Merwe, Clayton Kanyumba (from Lesotho), and Bryan Perrie (The Concrete Institute Managing Director).

CI RUNS ADVANCED CONCRETE COURSE Fourteen students – including one from as far afield as Qatar – have enrolled for The Concrete Institute’s (CI) 2014 Advanced Concrete Technology (ACT) diploma course.

The ACT course which is being presented in Midrand by the CI’s School of Concrete Technology, will culminate in July exams. The course includes four weeks of lectures by industry experts, blocked into two week-long sessions.

The globally-acclaimed ACT diploma offers: • World-wide acceptance as a holder of the leading qualification in concrete technology • An international qualification that is examined by the UKbased Institute of Concrete Technology • ACT graduates are sought-after in all concrete-related industries in South Africa and the rest of the African continent • Graduates can obtain membership of the Institute of Concrete Technology (ICT) allowing them to use the letters MICT after their names • Great networking opportunity for the candidates and the chance to meet many industry experts and leaders in different fields of concrete technology • The opportunity to gain detailed knowledge about all facets of concrete technology.

Bryan Perrie, MD of The Concrete Institute, says: “The 2014 ACT course will expose students to a wide range of concrete disciplines and insights that could definitely provide a competitive advantage to both the students and their companies. The Concrete Institute is proud to have been able to take over responsibility for presenting this universally acclaimed course in South Africa.”

Students for ACT courses are drawn from qualified civil engineers, cement chemists, concrete technologists and technicians involved in the building, construction, precast concrete, mining and also the cement, aggregate, admixture, and ready-mixed concrete industries.

PRECAST VOLUME 8 • ISSUE 1 • 2014

NEWS

5

PMSA TO HOLD TRAINING WORKSHOPS Pan Mixers South Africa (PMSA) - the

will showcase our products and services

largest supplier of concrete brick, block

and explain technological developments.”

and paving-making machinery and technol-

In addition PMSA will also be conducting

ogy in Africa - is providing greater value-

in-house training sessions for its staff to

added support to its client base through

ensure that they are kept up-to-date and

training workshops at its showroom and

skilled in the company’s product offering.

sales facility in Jet Park, Boksburg.

technology workshop, which was hosted

training and workshops is of particular

by Ludwig Moisture Control in January,

importance to PMSA, especially as our

was attended by the concrete ready-mix

pr oduc t and ser v ice o f f er ing to the

and the concrete precast sectors. An

southern African construction, mining

ABECE workshop for concrete roof tile

and precast concrete sectors continues

solutions, took place in February 2014,”

to expand ,” says PMSA marketing and

he added.

sales manager, Quintin Booysen.

Quintin Booysen.

“A moisture measuring and metering

“The decision to host regular open

Other seminars have been planned for

He notes that the workshops will

2014 and are advertised on the PMSA web-

be conducted monthly - 12 are planned

site, www.pmsa.com. Interested parties

for 2014 - and that up to 17 industry

can contact vannesa@panmixers.co.za.

professionals per session will be invited.

Booysen adds that PMSA is planning

“The seminars will be either half or

to host more in-depth, two-day courses

one-day events and will be presented by a

for equipment owners and prospective

variety of PMSA’s European suppliers. They

clients.

6

NEWS

SIKA AG 2013 SALES EXCEED CHF 5 BILLION FOR THE FIRST TIME Sika AG, is a globally active specialty

the demanding conditions prevailing in

chemicals company, which has its South

numerous markets, the results achieved

African Head Office in Durban, and branches

bear testimony to the str ength and

in all major SA cities. It supplies the building

robustness of Sika’s growth strategy.

and construction industry as well as manufacturing industries.

The region EMEA (Europe, Middle East, Africa) reported 8.5% growth for 2013.

Bolstered by a late European winter,

This positive trend was driven primarily by

Sika AG’s sales picked up momentum in

organic growth in eastern Europe, Africa,

the fourth quarter of 2013. Total sales

the Middle East and the UK, as well as by

grew 9.4% in European currencies in the

acquisitions.

Sika’s technology building in Switzerland.

2013 financial year. Adjusted for exchange

Business in North America picked up

rates, sales were 6.5% higher at CHF

considerably toward the end of the year,

With above-average growth, the Asia/

5.14 billion. This positive development is

resulting in a 2.3% sales increase. While

Pacific region also saw sales rise by

largely due to organic growth. The rapid

the residential real estate market recov-

12.5%. The OECD countries reported

integration of acquisitions also helped to

ered, the performance of the rest of the

increases in the single-digit percent-

drive growth momentum.

construction industry remained modest.

age range, while China, India, Indonesia,

The overall sales increase of 5.9% was

Latin America posted the strongest

attributable to organic growth, to which

growth of all regions. Sales were 15.1%

all regions contributed. Acquisition-related

higher, with every country and target

sales growth came to 3.5%. In light of

market recording increases.

P O Box 124, Sanlamhof, 7532 PRECAST VOLUME 8 • ISSUE 1 • 2014

Thailand, Malaysia and Vietnam all posted double-digit growth rates.

Sika is poised to continue growing in the current year.

NEWS

7

New concrete joint sealant from Mapei M ap e i S o u t h A f r i c a h a s in t r o du c e d

stopper formulated from high-quality

as well as suitable concrete mixes and the

Idrostop, an innovative PVC concrete

thermoplastic vinyl resins. T he prod-

right vibrator diameter, is available from

sealant f or ex pansion joints in ci v il,

uct has good resistance to mechanical

the Mapei South Africa technical team.

industrial and water retaining applications.

stresses and excellent chemical resist-

Idrostop PVC is supplied in 12 metre

Idrostop is available in two modules,

ance in alkalinic and acidic conditions and

rolls. Perfectly fused and sealed joints

Idrostop PVC BI ME for sealing internal

in sea water. Correctly installed, Idrostop

can be achieved by splicing on site with

construction and expansion joints, and

PVC will withstand positive and negative

using a thermostatically controlled weld-

Idrostop PVC BE for external construc-

water pressures. Advice on installation

ing blade and an adjustable jig.

Idrostop PVC BE.

Idrostop PVC BI ME.

tion and expansion joints. How Idrostop is applied depends on specifics such as structure type, joint type and joint m o v e m e n t, r e i n f o r c e m e n t p o si t i o n, hydrostatic head pressure, as well as wall thicknesses and profiles. Typical applications include water-tight structural joints in swimming pools, water tanks, retaining walls, tunnels, dams, canals, roof decks, basements and underground car parks.

All honeycombs, voids and segregation must be eliminated when using Idrostop PVC. It is an extremely flexible water

8

ARTICLE

STEADY AS SHE GOES – T The Concrete Manufacturers Association held a members’ report-back meeting on February 20 at Emperors Palace in Kempton Park. In addition to presentations by the CMA’s three directors, four guest speakers addressed a gathering of delegates comprised of both producer and non-producer CMA members.

• The membership drive has been very successful and the Association is now truly representative of the African continent, enjoying membership in Botswana, Namibia and Zimbabwe not to mention European countries such as Denmark, England and

In his presentation, CMA executive director,

how and where precast products are used

Germany. Since November 2012 thirty new

Wally Armstrong, thanked Techmatik SA

in the built environment, will be developed

members have joined. During that period

and Chryso for sponsoring the meeting. He

further and placed on the website.

only one producer member resigned and

also thanked the members for their loyalty

• Af ter 27 years the Virginia Sewer

one producer member was suspended.

and patience during 2013 which he said had

project has been concluded. The experiment

Moreover, membership enquires have

been a period of revision and restructuring.

has ser ved its purpose in convincing

been received from Kenya, Zambia and

Armstrong added that the CMA is now

consulting engineers to use pr ecast

Nigeria, The Ivory Coast and Saudi Arabia.

concrete piping for sewer systems.

At the time of the meeting there were

being run as a business. A new budgeting system, accounting structure and filing

• The CMA has been granted permission

43 producer members, 20 non-producer,

system – there is a file for each member

from the Competition Commission to

13 associate, four contractor members

– are in place and a set of accounts is

collate and distribute statistics collected

and two cement producers with a third

presented at every executive meeting.

from members, provided at least four

awaiting ratification.

Moreover, all expenses are carefully logged

manufacturers per product category

and are available for member review. Part

provide production figures.

• The Western Cape of fice has been closed. The establishment of member chap-

of the restructuring process entailed the

• The Association receives daily product

ters in all the major centres and in some of

creation of a common fee system which is

enquiries. Over 450 were logged during

the African countries is being investigated.

based on the two divisional structure of

2013 and these were presented at the

• The CMA intends presenting at the

the Association.

meeting as a pie chart. An additional 600

Road Paving Forum in October and gave

enquiries were received from Specifile.

two presentations, one on roofing and one

Some of the salient features of Armstrong’s presentation were as follows: • There will be no membership fee increase in 2014.

• Despite a severely curtailed advertising

• A CMA booklet which explains the

on paving during the Concrete Society’s

Association’s core activities and the

roadshow, Concrete’s Role in Human

advantages of becoming a member was

Settlements, in March.

published in November 2013.

• The CMA’s current social responsibility

spend during 2013, editorial publicity worth close on R2 million had been gained in 2013.

In addition Precast magazine is successfully promoting precast concrete applications with no financial risk to the CMA. • The web page is updated on a regular basis at minimal cost.

• The CMA exhibited at Totally Concrete 2 013 w hich demons tr a t e d tha t the Association was alive and well. A double stand has been r eser ved f or Totally Concrete 2014. John Cairns will make an electronic presentation on the “CMA Road” illustrating all the precast concrete products used in road building. A workshop room has been reserved in which a CMA panel of experts will be available to answer the public’s questions.

• A precast model, The World of Precast, which provides a better understanding of

PRECAST VOLUME 8 • ISSUE 1 • 2014

CMA executive director, Wally Armstrong, presenting to members at February’s report back meeting in Kempton Park.

ARTICLE

9

THE CMA REPORTS BACK programme includes working with Engineers

section on pipe jacking needs to be added

skills development, the creation of new

without Borders to supply exper tise

to SANS 667.

business, and with them jobs, and the

and pr oducts in the construction of

Voogt also referred to other standards:

formalisation of businesses, were some

a pedestrian bridge in Vredefort. The

SANS 508 -2012 Retaining Blocks which

of The Club’s activities covered in his

programme also involves working with the

has a query pending; SANS 1504, Pre-

presentation. The six-year old organisation

South African Road Federation and the

stressed Concrete Lintels, which is at the

has strong ties with the South African

Johannesburg Fire Department in a driver

peer group review stage; and SANS 1215,

Council of Women where it assists with

safety training project in Rhodes Park. The

Masonry Units, which is still in its infancy.

the development of women in the business

CMA’s role will be to install concrete block

environment. Moletsane said some of

pavers at the park.

The Club’s initiatives included an annual

• A manual on precast concrete manholes

entrepreneurship competition and the

is at an advanced stage.

establishment of businesses based on the

• This year’s AGM will be held together

recycling of waste materials. The Club’s own

with a strategy workshop in June.

dream is to become one of the country’s

• A decision was reached to hold the next

foremost Non Profit Organisations (NPOs).

Awards for Excellence competition in the

Gustaff Theunissen, head of marketing/

first quarter of 2016. A committee will be

sport of the Garsfontein High School in

appointed to organise the event and judging

Pretoria, made a powerful case in seeking

criteria will be reviewed.

assistance from the CMA and its members

Financial director, John Simpson, out-

for the building of a 120 student residence

lined the current financial status of the

at the school. He explained how, over the

Association. Although not legally obliged

past three years, the school had been

to submit audited accounts, Simpson said

transformed from an institution which Board member, Tshepo Moletsane of The Job Club, makes his presentation.

was rated as good to one of the country’s

ism. He also explained how the Association

Guest speakers

about the school’s bursary programme

had adopted a new memorandum of incor-

Graeme Smith, general manager sales and

for disadvantaged children and how, by

poration which was not only better suited

technical services of Sephaku Cement, one

adopting a caring attitude, these learn-

to current legal requirements, but was

of the CMA’s new producer members, gave

ers had flourished and gone on to note-

in line with the Association’s operational

a detailed and illuminating presentation on

worthy achievements both academically

and management structure. He added

the progress that Sepahku was making

and extra murally.

that members were being encouraged to

in launching South Africa’s first primary

Ganief Bardien, a senior manager: PICC

establish regional chapters in Cape Town,

cement production facility since 1934.

Localisation of the Industrial Development

Port Elizabeth and Durban.

it was in fact doing so in the interest of greater transparency and professional-

great schools. Theunissen also spoke

Smith talked about how Sepahku came

Corporation, talked about the Presidential

Technical director, Taco Voogt, spoke

into being, its major shareholders and

Infrastructure Coordinating Commission

about the CMA’s relationship with the

financing, the decisions which led to the

(PICC) and its role in facilitating the

South African Bureau of Standards in

choice of location for its Aganang and

government’s insfrastructure development

the revision of existing standards and

Delmas plants, the sourcing of state-of-

plan. First adopted in 2012, the plan aims to

the introduction of new ones. Voogt

the-art plant and equipment, the technical

improve the country’s economic landscape

attends quarterly meetings between the

advantages of modern cement plants,

while simultaneously creating a significant

CMA and SABS in which various issues

Sephaku’s branding methodology, technical

number of new jobs and strengthening the

ar e discussed in an in f ormal f or um.

product information and its philosophy of

delivery of basic services. Ganief said the

Three national standards are currently

supplying a product of great consistency

PICC’s mandate is to ensure the systematic

under review, SANS 1058-2012, Paving,

to the highest possible standard.

selection, planning, and monitoring of large

SANS 541, Paving Slabs and SANS 677,

Tshepo Moletsane, a board member of

projects so that they are well integrated

Concrete Pipes. A few minor points need

The Job Club, an Associate CMA member,

within the general economic framework. He

to be ironed out on the paving standard

said that he and his colleagues assisted

identified 18 strategic Integrated Projects

and water absorption in drycast products

people in the business environment with

(SIPs) which draw more than 150 projects

is being discussed on paving slabs. And a

at taining their dr eams. Mentor ship,

into a coherent package.

PRECAST VOLUME 8 • ISSUE 1 • 2014

10

COVER STORY

POLISHED CONCRETE TRANSFORMS FACTORY INTO SHOWROOM A prime example of how modern concrete technology can be used to blend cost-effective functionality with aesthetically pleasing finishes can be seen at CMA member PMSA’s (Pan Mixers South Africa) new showroom in Jet Park, Gauteng. Created from the gutted steel-framed shell of an old factory, the revamped 720m² building makes extensive use of polished concrete, both precast and in-situ.

It comprises 400m² of showroom, 280m²

Casting the precast structural wall panels.

The grinding of a precast panel prior to polishing.

PMSA’s new showroom was jointly

strategically located at either end of the

designed by Elite Architects and Booysen,

showroom as well as a 38m² reception

who has a building science degree from the

area and a first-floor wooden deck with a

University of the Witwatersrand.

stainless steel balustrade which is used

“We involved ourselves in the design

as a recreation and visitors meeting area.

because we were very specific about what

“Our customers’ products and natural

we wanted, especially in concrete usage.

lighting were essential drivers in preliminary

The polished load-bearing office walling was

design discussions”, said Quintin Booysen,

key to our overall objective of displaying

sales and marketing manager at PMSA.

the beauty and functionality of precast

“As Africa’s largest suppliers of brick

concrete in various colours. Another goal

and block making machinery and other

was to demonstrate concrete’s elegance

concrete-related equipment we sought

and versatility and we achieved this by

to use concrete wherever possible. And

introducing a lightweight tapered finish on

natural lighting would not only save energy,

two cantilevered walkways at either end of

but would showcase our product line-up to

the showroom.

best effect.

The polished panels were properly aligned with steel shims and supported with stays prior to the pouring of foundation concrete and the assembly of first-floor shutter work.

PRECAST VOLUME 8 • ISSUE 1 • 2014

course high quality concrete bricks.”

of ground floor and first-floor office space

“Actual design work began in August

“Another objective was to be the first

2011 and it took us approximately six

building in South Africa to use polished

months to convince the engineers to sign off

precast concrete load-bearing walls and

the design based on most of our wish list.

we wanted to demonstrate different types

“I met with them on a regular basis and

of finishes on these walls. Brick walls, by

we ironed out our different approaches

contrast, would have been much thicker. We

detail by detail. For example, they specified

not only installed precast load-bearing walls

double-cage reinforcing for the precast

between the ground-floor offices, but we

wall panels which support the entire upper

also incorporated other precast concrete

office structures. We, on the other hand,

elements in the building such as polished

held the view that single-sheet reinforcing

portal columns which frame the main

would work, and af ter revisiting their

entrance, kerbing (both wet and dry cast),

calculations the engineers adopted our

entrance stair slabs, bollards, numerous

suggestion. We also requested that the

examples of concrete block paving, and of

use of plastic rebar spacers be avoided

COVER STORY

11

as they would have been exposed on the surface after polishing. Instead we opted to suspend the rebar with thin wire which was cut after casting and curing.

“The deployment of precast hollow-core prestressed slabs for the upper-level flooring was considered, but the engineers wanted a 50mm topping which would have complicating matters unnecessarily. So in the end we opted for in-situ flooring both up and downstairs.

“The internal precast walling is the key architectural feature of the entire

Weighing seven tons each, installed polished panels, create office dividing walls and support the floor above.

and for casting the precast portal columns at the building’s main entrance.

structure in as much as we wanted the

“We used two Artevia blends, one with a

building to display something which was

very high aggregate content of 1 400kg per

unique - and I believe we achieved this

m³ for the showroom floor and the concrete

with the walling. In fact we were awarded

walls, and the other with an aggregate

a highly commended Artevia award from

content of 900kg per m³ for the upper-

Lafarge for the walls which were cast us-

level flooring where concrete pumping was

were cast using Peri shuttering and form-

ing Lafarge’s Artevia decorative concrete.

required. We specified the Artevia in six

work and Spancon assembled the steel

Moreover, we were complimented by for-

colours to highlight the unique identities of

reinforcement and managed the casting

mer Wits University lecturer and Cement

different work stations such as the office

in collaboration with Oceanside Trading.

and Concrete Institute researcher, Dr Rod

floors, the showroom floor, the reception

After curing, the walls and the columns

Rankin, for being true to the material. We

area and the external stairs.”

were polished by Oceanside Trading and

also used Artevia for all internal flooring

The precast walls and portal columns

A polished portal column is lifted prior placing and installation at the reception entrance.

then placed into position by crane. Weigh-

12

COVER STORY

ing five tons apiece, the walls were aligned

by approximately three to four millimetres

using steel shims, and steel stays were

and then polished to a fine sheen with HTC

used to hold them in place until the panel

polishers. No expoxy or resin was needed

foundations were cast. The portal columns

during polishing and nothing else except

weighed roughly six tons each, and besides

water is required for cleaning the floors,

their decorative function, they were used

which is done using a diamond impregnated

to support part of the roof structure and

twister pad mounted on an HTC machine.

curtain walling.

At 3 000 grit, the polishing gives the Ar-

“To save time, the new showroom floor

tevia floors a granite-like finish. Unlike tile

was laid unbonded on top of the old floor.

glazing, which wears away, Artevia floors

Dr Rankin advised that the new flooring

retain their smooth sheen indefinitely when

should not be reinforced and we followed

the twister pads are used for cleaning and

his advice. The reason given was that the

periodic maintenance.

rebar is often pushed too deeply into the

“Polished concrete flooring is becoming

concrete flooring. Moreover, it is often not

extremely important in SA. It is used exten-

cut correctly, factors which can lead to

sively in the food industry as well as in the

cracking,” said Booysen.

retail and industrial sectors. It is ideal for

A close up of one of the installed portal columns.

Abbeydale Building and Civils supplied the

warehouses because it doesn’t generate

ready-mix concrete from its PMSA concrete

dust from forklift tyres and there is very

supplied by CMA member, Savanna Bricks.

batching plant for the preparation and foun-

little tyre wear and no black marking. Also

T he non-polished concrete work, the

dation concrete work. PMSA handled the

the smoother and flatter a floor the higher

foundations and the screeding concrete

floor preparation work which involved scour-

one can work with forklifts.

was supplied by Abbeydale. CMA member,

ing the old floor using PMSA’s HTC grinding

“In addition to its functional and aes-

MVA Bricks supplied the kerbing, and CMA

machines and then covering the surface with

thetic attributes, the PMSA showroom is

member, C.E.L Paving and Pavetile supplied

sacrificial plastic sheeting. Artevia concrete

environmentally friendly. Besides abundant

15 different types of paving blocks which

was then poured onto the sheeting and

natural light, much of which floods in from

were laid around the front entrance and

levelled with a laser dumpy leveller.

translucent sheeting at the gable ends of

the parking area.

After curing, the floor was ground down

the building, we also erected a new roof

Booysen concluded by saying the project

which was insulated with a non-combustible

is regarded as a great success. “We

glass wool, supplied by Isover.

achieved what we set out to do, namely,

“The natural light theme was extended

to create a new showroom which not only

to our offices which are all fronted with

displays concrete block making and related

frameless armour-plated glass and the

machinery but which demonstrates various

upper level balustrades were assembled

types of concrete usage in innovative and

using stainless steel tubing to create a

aesthetically pleasing applications.”

nautical effect.”

The external walls incorporate part of the old wall and run to 330mm. They were Precast polished stairs at the showroom entrance are flanked by portal columns.

built with high-quality concrete bricks

The upper level walkway, which was tapered on the underside for aesthetic effect.

The recently completed PMSA showroom with a polished concrete floor.

PRECAST VOLUME 8 • ISSUE 1 • 2014

PMSA’s reception area, which shows off the polished concrete floor to good effect.

ARTICLE

15

RECORD RETAINING-WALL HEIGHT REACHED IN KZN The highest vertical Terrace Blok® retaining wall to have been built in KwaZulu-Natal was supplied by CMA member, Aveng Manufacturing Infraset. Erected with geogrids at the Watercrest Mall development in Waterfall near Hillcrest, the Terrace Blok® wall is one of five which form part of the civil and earthwork preparations of the 43 000m² development.

Begun simultaneously with the demolition

One of the 60m retaining walls at Watercrest Mall.

of an existing shopping centre, the mall is being built by Stefanutti Stocks, and when

Terrace Blok® TB 500 vertical retaining

completed in October 2014, it will be the

blocks because they allow for a vertical

Durban area’s third largest retail mall.

(90˚) wall configuration, unlike most other

The walls were built to shore up level

retaining wall blocks which only go up to 70˚.

platforms for the construction of the multi-

“One needs a very reliable concrete block

level shopping mall. The two largest are

when building retaining walls, especially walls

each 120m long, one topping out at 15m

as high and as steep as those at Water-

and the other at nine metres. The three

crest. We know that Terrace Blok® is a reli-

remaining walls all span 60m with maximum

able product. We have used it extensively,

heights ranging between eight and 10m.

and it has never failed us,” said Waplington.

Based on a 120-year lifespan, the

Extensive geotechnical testing was

walls were designed by Leon Cloete of

undertaken before the walls were designed

the engineering and project management

to establish drained cohesion and drained

concern, MCJ Engineers, and by Bazi

friction angles.

D uk h a n o f t h e c i v il, s t r u c t ur a l a n d

“We found the friction angles to be

geotechnical engineering consultancy, Bazi

around 32-35° and cohesion was of the

Dukhan Consulting Engineers. Cloete and

order of five to 10KPa,” said Dukhan.

Dukhan also supervised the construction

“We designed the walls at angles of 70˚

of the walls.

to 83˚ to maximize the amount of level

The tender bid called for the supply, design

ground for building purposes and besides

and construction of retaining measures from

Aveng Manufacturing Infraset’s Terrace

several contractors. Competitive bids were

Bloks® , we used another readily available

assessed on the basis of price and construc-

product, RockGrid® PC 100, supplied by

tion viability. The contract was awarded to

another CMA member, Kaytech. RockGrid®

Advanced Retaining and Paving, which has

PC 100 is a new generation high-tensile

constructed several drystack retaining walls in Durban and surrounding areas.

Advanced contracts manager, Jason Waplington, said that the company selected

composite geotextile which offers the A 15m high section of retaining wall at the Watercrest Mall development which was built using Aveng Manufacturing Infraset’s Terrace Blok TB500 concrete retaining blocks.

strength characteristics of woven geotextiles and the favourable hydraulic qualities of non-woven geotextiles,” Dukhan added.

PRECAST VOLUME 8 • ISSUE 1 • 2014

16

ARTICLE

The design was undertaken in compliance w i th S A NS 2 07: 2 0 0 6 “D e sign an d construction of reinforced soils and fills” and input from case histories of similar walls designed by Canadian engineers, R. Bathurst and M Simac.

In calculating the overall stability of the wall, the reinforced soil block was regarded as a rigid mass. Geogrid spacing was calculated using various software programmes on limit equilibriums. (SRWall, MacStars, PCStabl, Snail etc).

Finite element analyses were also undertaken as a check on serviceability criteria.

“The backfill was benched in steps and we used seven metre geotextile tiebacks at either every second, third or fourth course of blocks. However, in some areas we had to use geogrid in combination with steel anchors for additional reinforcing.”

RockRid® PC 100, supplied by Kaytech, was laid every at every second, third or fourth course of blocks.

The backfill consists of weathered

spectively, and this provides the reinforce-

Natal Group sandstone and approximately

ment characteristics we required - with

30 000m3 was used in the reinforced zone.

minimal distortion. Other characteristics

RockGrid® PC 100 was used to anchor the

which suited our design were low creep,

facing blocks and inhibit wall movement

and high transmissivity. The latter offers

caused by frictional stresses between the

sufficient drainage to reduce pore pressure

geogrid and the backfill.

build-up in the reinforced soil which in turn

“The material exhibits a high tensile modulus (high tensile strength at low elonFigure 1: Spacing of geogrids

improves the shear resistance and overall structural stability,” said Dukhan.

gations) of 18kN/m, 45kN/m and 100kN/m

The geogrid tension requirement for

at 2%, 5% and 10% strain(ISO10319) re-

the 120-year design life of the structure was calculated as 45kN/m. Rockgrid PC 100 offers a long-term design strength of 52kN/m and creep-limiting strength of 60kN/m over that period. Similarly, the tension demand for the 120-year life for the 15m wall sections was calculated as 45kN/m.

In order to prevent crushing of the lower blocks, they were filled with 25MPa concrete as opposed to the upper blocks which were filled with soilcrete.

The foundations were based on conventional strip footing using steel reinforcement, but in areas of rock deposits, we were able to make the foundation slightly smaller.

Drainage was installed at r egular intervals using clean Umgeni sand 100 x

Watercrest Mall under construction. One of the 60m retaining walls is in the foreground.

PRECAST VOLUME 8 • ISSUE 1 • 2014

100mm wick drains.

ARTICLE

article

19

The Emirates Arena and the Sir Chris Hoy Velodrome in Glasgow, Scotland. (McAteer Photographer)

LOCAL BUILDING PRACTICE ANTIQUATED AND EXPENSIVE South Africa is 30 to 40 years behind the developed and much of the developing world in the construction of multi-storey buildings. The substantial economic advantages which European, American and Asian construction companies are realising through the extensive use of hollow-core concrete slabs and other precast concrete elements, has to date, largely been lost on local property developers.

lost much of their in-situ expertise during

Precast concrete is the preferred building

and columns are actually used, they are

cast concrete industry is a healthy one

medium for multi-storey superstructures

specified by the construction engineer

and companies such as CMA member,

in much of the world. In fact in Europe

af ter the architects’ plans have been

the Echo Group, Africa’s largest precast

today, 90% of building superstructures

drawn. Only very rarely is precast built into

hollow-core supplier, are already geared to

comprise precast concrete with only 10%

architects’ designs at the outset, which

assist the local building industry make the

being cast in-situ.

means that when hollow-core slabs are

switch. It seems evident that as soon as

In South Africa the reverse applies.

specified by the engineer, the plans must

some of the major architectural practices

Pr ecast concr ete is r egar ded as an

be returned to the architect and amended,

start to design with precast, it won’t be

alternative system while 90% of the

and this of course adds to the overall cost.

long before the rest follow.

concrete used on local building construction

Notwithstanding South Africa’s seeming

In 2009 Echo Prestress commissioned

is still cast in-situ. This results in buildings

reluctance to take advantage of hollow-core

the Concrete Manufactures Association

w hich ar e f ar mor e costl y and time

and precast technology, this situation looks

(CMA) to manage cost case-studies on

consuming to erect, to the detriment of

set to change, and quite rapidly too. Not as

two medium-rise buildings, Bridgeview, a

property developers and the consumer.

one would suspect due to the substantial

five-storey load-bearing masonry residen-

In Europe building with precast elements

cost/time and other advantages of the tech-

tial structure in Johannesburg, and Capital

is the default system and is incorporated

nology, but for the more mundane reason

Park, a seven-storey residential building

into the design at the outset. In South

that the skills pool in in-situ building practice

in Pretoria. Both buildings were built with

Africa when hollow-core slab flooring and

has shown a marked decline over the past

hollow-core slabs and the case study was

other precast elements such as beams

five years. Small to medium companies have

conducted to highlight hollow-core’s superior

the downturn and now it is only the major construction companies which retain sufficient skills to pursue in-situ construction.

Hollow-core and precast concrete is ideally placed to take up the slack.

Fortunately for South Africa the pre-

PRECAST VOLUME 8 • ISSUE 1 • 2014

ARTICLE

cost attributes over in-situ construction.

Both projects realised substantial

21

utilisation, lower floor/floor heights and

Emirates Arena and the Sir Chris Hoy

more profitable buildings.

Velodrome, both situated on a 10.5 hectare

savings in their construction costs, 30.76%

As its name implies hollow-core slabs

site in the East End of Glasgow, and a

in the case of Capital Park and 23.79%

are cast with continuous voids which

multi-storey car park adjacent to the City’s

on the Bridgeview project. These results

reduce weight and cost and offer excel-

exhibition and conference site.

were authenticated by quantity surveyors,

lent sound insulation. Concrete batching

In addition, precast concrete cladding

Bathuleng, Wallace, and Raubenheimer

plants with automatic control of weights,

was used on much of the external facades

and design verification was handled by DG

cement/water ratios and the steam cur-

of the Arena and Velodrome as well as an

Consulting Engineers (Capital Park) and

ing of concrete in controlled conditions,

interconnecting hub between them.

Knutton Consulting (Bridgeview).

mean that very high and consistent quality

Hollow-core slabs were first introduced

standards are achieved.

Robust, durable and providing inherent acoustic and thermal qualities, the architec-

in the 1950s to fast-track flooring in multi-

The great versatility of hollow-core slabs

turally striking selection of an almost black

storey apartments during the reconstruc-

allows their use not only for floors, but for

exposed granite aggregate finish to the

tion of a bomb-ravaged Europe in the wake

high-end security walls, retaining walls and

precast concrete cladding on both buildings

of the Second World War. And over the

created a rugged impression, mirroring the

years other precast concrete elements

heritage of the region’s coal mining past and

such as beams, columns, cladding, wall-

providing a lasting legacy for its future. The

ing, double T slabs and staircases, were

‘shiplap’ pattern represents the different

adopted such that, as we have seen, 90%

seams evident in an exposed coalface.

of building superstructure concrete in

Also comprising a high percentage of

today’s Europe is precast.

precast concrete elements, the car park

Hollow-core slabs can be used for most applications requiring a floor and roofing system. Flats, office buildings, schools, and

was constructed using building contractor, Capital Park, Pretoria.

SCC’s newly developed inver ted IPCs (Integrated Precast Component) and PFV

hotels all lend themselves to the technology.

cladding. The numerous examples of pre-

(Precast Finished Voided) hollow-core

They are produced in well-equipped, up-

cast buildings in other parts of the world

flooring system. Manufactured at SCC’s

to-date plants using advanced technologies

demonstrate that the various possibilities

Reddish site, the system offers a high

where it is far easier to ensure consistently

of hollow-core slabs have not been fully ex-

standard of specification and quality finish

high quality standards than it is in an in-situ

ploited. In fact its development world-wide

within a realistic price tag.

building environment.

should be considered as in its infancy.

Slabs are manufactured on steel casting

Built off pile foundations, the garage’s seven suspended decks are accessed

beds, and in the case of the Echo Group,

Building with precast in Europe

by two semi-circular ramps on its north

using slipform technology. Echo manufac-

By way of example, four recently completed

elevation. These too, form part of SCC’s

tures both reinforced and prestressed

structures, three in Glasgow, Scotland, and

precast car-park methodology, as they are

hollow-core slabs. Reinforced slabs run to

the other in Manchester, UK, all contain a

assembled entirely from precast concrete

a maximum length of five metres whereas

high percentage of precast concrete ele-

and are thought to be the first of their

the additional strength afforded by pre-

ments and are typical of the type of precast

type to be constructed in this way.

stressing facilitates spans of up to 12

concrete construction which dominates the

metres. Longer spans and the capacity

European construction landscape.

to carry heavy loads means better space

T he Scottish buildings include the

At the peak of construction, the main frame was erected at a rate of 925m2 /day, enough space to park 48 cars, along with their respective driving aisles. One of the benefits of the system is the addition of pedestrian guarding, which is pre-assembled and fixed to the structural members before delivery to site. This avoids the need for temporary guard rails and protects the workforce as soon as the unit is erected.

Pedestrian access to the parking decks is via a main stair tower on the south elevation. It is connected to a podium deck and link bridge at level two, and provides access over the carriageway to the arena site. The stair tower has four machine-roomless

2

A 24,000m health, psychology and social-care building under construction at Manchester Metropolitan University’s new campus.

lifts, with a high standard of finish throughout. There are two additional escape cores,

PRECAST VOLUME 8 • ISSUE 1 • 2014

22

ARTICLE

one each on the northwest and northeast

precast concrete components on the

five weeks early due to the back-propping

corners of the building.

project involving 500 deliveries.

design and integration of J&P Building

The Manchester project is a £60 million

The overall on-site duration was only 21

24,000m2 health, psychology and social-

weeks with lower level floors handed over

Systems’ BSF Connectors.

care building on the City’s Metropolitan

European standards adopted locally

University’s new campus.

In order to accommodate South Africa’s

It is the largest construction project in

switch to precast construction, local pre-

a ten-year consolidation plan. The scheme

cast companies such as Echo, are adopting

has utilised the benefits of precast con-

European standards, as are several con-

crete extensively and will be the greenest

struction-related engineering practices.

university campus in the UK, with environ-

Euro codes for precast concrete are far

mental sustainability integral to all aspects

more detailed than local codes and provide

of the design.

extensive and very detailed guidance, espe-

Design and build precast specialist,

cially on hollow-core slabs. By contrast, the

Creagh Concrete Products Ltd, provided

local standard for the suspended precast

a superstructure including structural

slab is very basic. For example, it doesn’t

cores and lift shafts, stairs and landings,

cover durability properties and thermal

columns (including 17 metre circular

values are not well described. Nor are U

single formed columns), beams, steel

values and sound transmission values. For

beams, plate flooring and hollow-core

these and other reasons local construc-

slabs including structural toppings. Added

tion professionals are turning to European

to this was the requirement to create a TABS building using cast-in embedded pipewor k . O v er all ther e wer e 2,500

standards and specifications for precast A multi-storey car park built extensively with precast concrete elements in Glasgow, Scotland. (Photograph SCC Ltd).

concrete in their quest to build better buildings more efficiently.

OUR DOOR

IS OPEN BECOME PART OF THE FUTURE

WE INVITE ALL PRECAST CONCRETE MANUFACTURERS TO JOIN US *

m

* TERMS AND CONDITIONS APPLY

a

nu

facturer

s as

n

co

iatio

ncrete

soc

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lity

cast in conc

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CONCRETE MANUFACTURERS ASSOCIATION 16 Horn Street, Kempton Park, 1620 PostNet Suite 8612, Private Bag X32, Kempton Park, 1620 Tel +27 11 805 6742 • Fax +27 86 524 9216 • E-mail: admin@cma.org.za

www.cma.org.za

24

ARTICLE

CMA MEMBERSHIP - EIGHT MORE AN As at the end of February a further eight companies had joined the CMA bringing to 30 the number of new enrolments since November 2012. The new members are: Civilworks; Doubell Brick Machines; HawkeyePedershaab; Portland Hollowcore; Powergate Construction; SamJung Industries Co.Ltd; Sephaku Cement; and Valcal International Exports.

The company also offers a complete range of handling solutions which increase productivity and improve plant safety. Furthermore, a wide range of equipment such as D-Load testing and hydrostatic testing is offered to allow concrete producers to monitor their product quality.

The success of the membership drive

Doubell Machines

means that the Association is now truly

Doubell Machines is a manufacturer of

batching and mixing plants and reinforcement

representative of the African continent,

brick-making machines and allied equipment.

cage welding equipment is another service

enjoying representation in Botswana,

Based in Port Elizabeth, its customer base

offered by HawkeyePedershaab. It makes

Namibia and Zimbabwe. Moreover, enquires

extends across the world.

project management much easier for the

have been received from Kenya, Zambia and

Since inception in 1981, the focus has

Nigeria, The Ivory Coast and Saudi Arabia.

been on providing affordable machinery

Further afield, membership extends to

to help improve living standards among

South Korea and European countries such

impoverished South Africans.

as Denmark, England and Germany.

Outlined below are brief profiles on some of the new members:

Turnkey installations including concrete

concrete producer.

Doubell Machines has always striven for quality and its brick and block machines have proven their worth repeatedly. Without compromising on quality, the company

Civilworks

limits price increases to one a year, despite

Civilworks was established in Johannes-

much more frequent input costs.

burg in 2002. The company manufactures

While its core business focus is brick-

manholes and associated concrete prod-

making machines, the company has expanded

ucts in a 40 000m² factory for the roads,

into all brick-making related machinery,

Portland Hollowcore

stormwater, sewer, and water sectors.

including mixers, barrows, hoppers and

Portland Hollowcore, a division of the Port-

This includes a wide range of telecoms and

other complementary offerings.

land Group, is situated in the picturesque

electrical manholes and drawboxes.

ISO9001-2008 certification stimulates

HawkeyePedershaab vertical casting.

Contermanskloof in Durbanville, Cape Town.

The company also manufactures spe-

exports and increases customer confidence

Portland was founded in 1988 as a

cialist or custom precast items for major

in the company’s business principles and

property developing company, but has since

projects (GFIP, Gautrain, NMPP, and so on).

quality manufacturing processes.

been transformed into one of the leading

In addition it supplies thermoplastic pipe

suppliers of aggregates, ready mix and

systems, imported cast iron and ductile

hollow-core in the Western Cape.

iron frames, as well as lids and other gen-

In 2000 Por tland acquired a 65ha

eral items to the civil engineering sector.

quarry in Durbanville and a year later, three

C i v il w or k’s f ac t or y is si tua t e d in

Portland Readymix plants were installed.

Klipriver, Gauteng and currently employs

Portland Hollowcore was opened in

134 people. The company also enjoys full

2008, after the installation of the state-of-

representation in Cape Town and Durban.

the-art Elematic systems, imported from Finland. The company’s own aggregates are used for the production of the hollowcore slabs and all products are backed The Doubell Jumbo MK3 making 7x M6 blocks per drop.

HawkeyePedershaab HawkeyePedershaab manufactures machinery for the production of concrete pipes, manholes, culverts and related products.

Using a vertical casting technique with semi-dry concrete, demoulding can take A specialised precast concrete application by Civilworks.

PRECAST VOLUME 8 • ISSUE 1 • 2014

place immediately after casting.

A Portland Hollowcore slab.

ARTICLE

AND COUNTING

25

other concrete-block related products for

the total project cost was spent locally

23 years and its research and develop-

on the onshore portion of the project,

ment programme has achieved substantial

which included procurement of all cement,

improvements.

reinforcing steel, and aggregates, as well

by tight quality control, which brings a

SamJung prides itself on customer

as, inter alia, suppliers for the construction

guarantee of strength and workability on

service and customer satisfaction in 54

of access roads and for the installation of

the construction site. Portland Hollowcore

countries is very high.

water reticulation and Eskom power.

also uses its readymix division for the supply of concrete in the production of precast stairs and beams.

Portland’s main operations take place in one location, making it easier for employees to communicate and manage their tasks, ensuring the effective integration of the different operating divisions.

SamJung steel pallets.

Powergate Construction

Sephaku Cement

Powergate Construction is a family-owned

Sephaku Cement is South Africa’s first

business offering block gravity retaining

new primary cement producer since 1934.

wall and gabion basket solutions to the

An associate company of JSE-listed

general construction industry. Active in

Sephaku Holdings Limited, Sephaku Cement

the mining, private property and public

is a 64%-owned subsidiary of Dangote

infrastructure sectors, Powergate Con-

Cement Plc. Dangote has invested more

struction provides trouble-free service in

than R1.1 billion in the venture, representing

the design and construction phases.

the largest investment in a South African

A policy of continuous improvement

enterprise by an African company.

The pre-heater tower and raw-meal silo at Sephaku Cement’s Aganang plant.

VALCAL INTERNATIONAL

ensures that all employees are given ongo-

The project involves two separate plants,

VA L C A L I N T E R N AT I O N A L h a s b e e n

ing training in both technical aspects and

namely, a clinker and cement manufacturing

installing retaining wall systems since

health and safety. This ensures they are

plant named Aganang, near Lichtenburg in

1993. Specialist retaining wall practitioner

able to offer the best onsite service to main

the North West Province, which will produce

and VA L C A L IN T ERN AT ION A L owner,

contractors and consultants.

approximately 1.9 million tons of clinker and

Pandelis Valarakis has over 17 years’

Powergate Construction’s customers

1.2 million tons of cement per annum when

experience in the construction industry.

also make substantial savings by taking

full production is reached in June this year.

Together with his highly trained team,

advantage of the company’s high-quality

And a milling plant in Delmas, Mpumalanga,

he brings his personal expertise to each

turnkey solutions and further customer val-

using 50% of Aganang’s clinker production,

project which ensures best-practice

ue is added through post-project support.

will yield an estimated 1.4 million tons of

professionalism.

cement annually.

VALCAL INTERNATIONAL has a BEE

The Delmas plant has been commissioned

rating of 2. Using a variety of retaining

and is in full production with just a few

wall blocks, which have been designed as

minor peripheral construction tasks to be

the perfect solution for the widest possible

completed. Three cement grades are being

range of soil retention and landscaping

produced all of them to SANS 50197-1.

requirements, VALCAL INTERNATIONAL

They are a 32,5, a 42,5 and a 52,5 type

can professionally design, supply and install

cement branded as Sephaku 32, Sephaku

retaining walls to suit every need.

42 and Sephaku 52 respectively.

Sinoma International Engineering Co. was A Powergate Construction retaining wall.

awarded the R2.7bn turnkey contract to design, fabricate, build and commission the

Samjung Industries Co., Ltd

Aganang and Delmas plants. State-of-the-

SamJung Industries Co., Ltd., is a profes-

art plant from some of the world’s leading

sional manufacturer of high-quality steel

equipment suppliers, including German-engi-

pallets for the production of various types

neered mills from Loeshe GmbH, as well as

of concrete blocks.

other key equipment from leading European

The company has been producing and

suppliers are included in the turnkey project.

supplying best-quality steel pallets and

In addition, approximately one third of

A VALCAL INTERNATIONAL retaining wall.

PRECAST VOLUME 8 • ISSUE 1 • 2014

26

ARTICLE

A cement-free concrete which equals or betters its standard equivalent has been high on the environmental lobby’s wish list for decades. Their persistence is on the threshold of being rewarded. Although in its infancy, cement-free concrete is now a reality. It gains an impressive 4MPa in six hours and 51MPa in 28 days. Moreover, it is self-compacting, requires no steam or water during curing and is hard enough to walk on after only 15 minutes.

This remarkable achievement holds great promise for massive reductions in carbon footprints worldwide as every ton of cement produced yields a ton of carbon dioxide. Equally significant is the fact that the technology is not the invention of the Ivy League fraternity on some far-flung shore, but is as South African as the bushveld.

Based on what is known as ARC (Advanced Re-Crystallisation Technology), it is the creation of Cyril Attwell, group concrete and research manager at Murray & Roberts. Attwell runs M&R’s centre for concrete excellence and also heads its innovation portfolio.

It all began in 1999 when Attwell was working for Samson Construction Products.

He was contacted by a contracts manager,

ALL SET FOR CEMENT-FREE CONCRETE A close-up of the Gautrain bridge over Allandale Road in Midrand.

Anton Botha, who sought a concrete which would achieve a compressive strength of

body, which, like concrete, is comprised

affected all the minerals in the blend and we

12MPa in 12 hours at an ambient tempera-

largely of water.

wanted an agent which only reacted with

ture of -8˚c. Botha wanted the concrete to

“Billions of dollars are spent on medical

construct the Mangaung Prison in Bloem-

technology every year as opposed to only a

“We eventually opted for tetrapotasium

fontein and by the time he spoke to Attwell,

few million on concrete and I reasoned that

pyrophosphate (TKPP) and found that half

he had already approached several senior

if we tapped into existing medical research

a litre per cubic metre of concrete did the

concrete technologists. All of them claimed

we could learn something useful about con-

trick. My peers thought I had lost it because

it was a mission impossible.

crete,” he said.

TKPP is widely regarded as a retarder and

calcium rich systems.

Cold weather is one of the major bug-

“So we examined how cold tempera-

our industry generally uses between two

bears of the concrete industry because it

tures affect the human body, and in par-

to 40 litres per cubic metre of concrete.

doesn’t, or rather didn’t, set (crystallise)

ticular, how they lower saturation levels.

However, we found that half a litre was

below 5˚C in those days. This was because

We also observed how alcohol changes

sufficient to act as a masking agent and

cement would only be partially saturated at

the saturation levels of most minerals in

allowed more calcium to dissolve. This was

below 5˚C, and for concrete to set properly,

the blood. We then looked for a substance

followed by some biodegrading and suddenly

full saturation is required.

which would improve the saturation levels

we were left with a super-saturated solu-

of concrete and we came across EDTA

tion which enabled the concrete to set and

(Ethylenediaminetetraacetic acid).

gain strength at very low temperatures.

Attwell relishes a challenge and took the project on board. But instead of relying on conventional concrete technology, he began

“A 25-year patent on EDTA had expired

“The cost of our mix was R297 per

by focusing on the chemistry of the human

the year before, but in trying it we found it

cubic metre and we had only used 350kg

PRECAST VOLUME 8 • ISSUE 1 • 2014

ARTICLE

27

variables and by adding just two more we were able to make a substantial difference.

“Af ter Mangaung we took on more projects, each time adding more variables.

Gautrain was one of our next major projects, and here we made an intuitive leap into unchartered territory using all 38 variables.

“At the time the Gautrain Precast yard was the second largest in the world, and according to original estimates, the project was to have used 344 000 tons of cement. This would have resulted in releasing a like amount of carbon dioxide into the atmosphere and would have taken a forest spanning 540km² a year to absorb.

“But by using ARC Technology and by matching the chemistry of the human skeleton to concrete crystallography, we Concrete beams used on the Gautrain project, produced with substantially reduced cement quantities.

were able to replace a substantial amount of the cement with a waste product, PFA (flyash), from coal fired power stations, and in the end, we only needed 210 000 tons of cement. This almost halved the carbon footprint.

“Our binder element comprised 280kg of a 42.5N cement and 140kg of siliceous PFA per cubic metre of concrete, or 32% of the 420kg total binder material, and no rapid hardener was used.

“The first time our French partners saw the mix design they believed we would only achieve 40MPa with a very low safety fac-

Some of the Gautrain viaducts, produced using ARC Technology.

tor. Similarly, representatives of the Coal Ash Association of South Africa thought that this was a 35 or 40MPa design with some safety margin, but not much. What

of cement as opposed to over 500kg used

we actually achieved on Gautrain, and

in standard concrete technology. We also

which was fully audited, was a compres-

achieved a 200 slump or a 550 to 600 flow,

sive strength of 74MPa – approximately

so it was a very wet concrete. Gaining early

34MPa higher than anyone thought we

strength is very difficult and at 11.8MPa we

would. Moreover, because we had tied up

were just short of the 12MPa required by

the variables we were able to optimise

Anton. But this was good enough to proceed

the crystallography, and by doing so, were

and our results were verified by him.

able to achieve average flexural strengths

“This was when Arc Technology was

of 16.6MPa.

born. Unlike standard concrete technology

“Flexural strength is generally around

which uses just three variables in concrete

10% of compressive strength. And usually,

production, namely, particle shape, parti-

as the compressive strength increases

cle size, and the water binding ratio, ARC

the flexural strength ratio decreases. One

Technology embraces 38, those three and

would normally expect a 74MPa concrete

35 others. Chemical make-up, saturation

to have a flexural strength of 6.5 to 7MPa

levels, reaction kinetics, magnetics, and so

whereas our 16.6MPa was 22% of the

on, are some of the elements which give us

compressive strength. These tests were

a much more detailed mix design. On the

carried out by a fully accredited SANAS

Mangaung Prison project we only used five

lab, Beton-lab.

PRECAST VOLUME 8 • ISSUE 1 • 2014

28

ARTICLE

15% cement, or half a pocket per cube.”

“The Gautrain project demonstrated the power of ARC Technology. Besides

Another first for Portside was that it

interweaving all the variables, we also

was the scene of the highest single-stage

augmented the crystallography. Or to

concrete pumping in South Africa to date.

put it another way we optimised the way

Because of its perfect material matrix, we

molecules interacted so that everything

were able to pump the concrete to a height

was chemically balanced. We even got a

of 142m from across the street and our

chemical reaction from the sand, and that

pressure never exceeded 100 bar which is

gave us additional strength. This is some-

quite exceptional.

thing that standard concrete technology

“After Portside moving to cement-free

does not take into account. In fact we

concrete using geopolymers was an easy

achieved strengths which were factors

transition. We reasoned that if one could

higher and not just a few classes higher.

get away with half a pocket of cement

And we did this without the aid of steam

why use cement at all? We initiated the

or accelerators.

process using an activated waste material

After Gautrain, ARC Technology scored

at the new City Deep container depot. We

several other successes, one of the most

conducted some shrinkage tests and these

recent being Portside, Cape Town’s tallest

yielded results of 0.022% as opposed to

skyscraper. The concrete used here played

cement-based concrete which is normally

a significant role in the high green star rat-

rated at 0.045%. SANS parameters con-

ing awarded to the project.

sider anything below 0.025 to be effectively zero shrinkage.

“Again, we made extensive use of a waste product in the binder; on this oc-

“Another advantage of geopolymer con-

casion it was corex slag sourced from the

crete is it’s not water cured – it’s solely air

steel foundry at Saldanha. Our binder mix ratio was 35% cement to 65% corex slag and we combined the binder with a hornfels aggregate and some dune sand. At 7075%, aggregates and a small amount of water made up the balance of the overall mix. The water binder ratio was approximately 0.69.

“This was the first time that a concrete with more than 50% slag had been used on a building, let alone Cape Town’s tallest structure, and the project’s concrete consultant, Professor Mark Alexander of the University of Cape Town, reviewed our mix designs. His testing revealed exceptionally high durability levels, especially when the low binder content was factored in.

“Three grades of concrete were specified for Portside, a 60MPa mix for some of the weight-bearing columns, 40MPa for most of the building and 15MPa for some of the non-structural elements. On the 60MPa concrete we realised actual strengths of 94MPa. This was achieved using three pockets of cement (150kg), 300kg of the slag and 195lt water.

“We averaged 55MPa on the 40MPa mix using 98kg of cement or less than two pockets per cube, 185kg corex slag and 195lt water. And we achieved up to 33MPa on the 15MPa mix using 85% slag and only

PRECAST VOLUME 8 • ISSUE 1 • 2014

Portside, Cape Town’s highest building, nears completion.

ARTICLE

29

cured. This results in huge water savings and very little cracking.

“We also introduced bubble technology at City Deep. It gives the concrete a carbonised coating which after a mere 10 to 15 minutes after casting hardens into a protective crust. This can be safely walked on after only 15 minutes. Within 4 hours the crust can be broken up with a vibrator so that all the material is reintegrated.

Essentially the bubble effect means one can vibrate and leave. No plastic covering or curing membranes are required.

“A saving of approximately 30% on materials and at least 25% on labour was made at City Deep, and we achieved strengths of 51MPa in 28 days and a flexural strength of

Cyril Attwell.

polymer. And once bound, it remains bound.”

4.2MPa - an eight percent ratio of flexural

Attwell says that his research team is

to compressive strength. Normal concrete

a leader in material engineering and that

would be 4.5MPa flexural and we are working

geopolymers represent a small fraction of

to improve our ratio considerably.

its research programme.

“We have begun producing cement-free

“We have designed many pr ojects

bricks using the activated waste/geopoly-

across the world and nearly all of them use

mer concrete. They contain PFA, dolomite

waste material.

aggregates, a geopolymer and a catalyst.

“One of our current development pro-

After seven days the concrete reaches a

jects is coral protection in harbours where

compressive strength of 15 to 22 MPa.

huge build ups of carbon dioxide destroy

“We are also replacing virgin aggregate

sea life. An electro-chemical system is

with waste material such as bot ash

introduced which actually absorbs carbon

or slag aggregate, ingredients usually

dioxide from the ocean. Moreover, it encour-

avoided in normal concrete production.

ages the growth of and sea life and protects

This alternative material is yielding seven-

concrete from chemical degradation.

day strengths of 40-45MPa. In addition,

“Another of our marine-based projects is

we are cross-polymerising the aggregate

situated in Fishhoek on the Cape Peninsula

with the binder so that all ingredients

where we are planning to build tidal turbines

in the mix are chemically active. As a

made of precast geopolymer concrete and

result we have reduced costs by 50%

protected with the coral technology.

and doubled compressive strengths. We

“O ther cur r ent r esear ch invol ves

intend implementing this technology at

using mushrooms to stabilise road sub-

CMA member, Technicrete in the near

grades rather than the normal cement.

future which will mean a 68 000 ton annual

The biggest problem with cement is that

reduction in carbon dioxide emissions.

it eventually gets washed away by water,

“What’s more, we intend using geopoly-

and this is what creates potholes. Mush-

mer for the production of concrete pipes

rooms thrive on water and they don’t need

because its acid resistance far exceeds

sunlight. So the more water the better

that of normal concrete piping. In fact it

the stabilisation.

is equivalent to the resistance found in HDPE-lined pipes.

“We are also using the basic oyster mushroom to clean up spills of petrol,

“Another major benefit of SCGC is that

oil and diesel because they convert hy-

it forms a molecular cage which absorbs

drocarbons into fungus sugars. The nice

radio-active elements such as uranium and

thing is if you apply the correct amount

cerium. England’s University of Sheffield, led

of spores, the spill disappears within 14

by John Provis, has actually bound nuclear

days. Moreover, you’re left with a crop of

waste in geopolymer. Not a drop of radiation

beautiful oyster mushrooms which can be

can escape once it’s been bound into a geo-

harvested and eaten.”

PRECAST VOLUME 8 • ISSUE 1 • 2014

30

APPLICATIONS

Fleet Management software boosts service levels of Ethiopian Cement plant CargoWare, the logistics software divi-

order processing, trip documentation

with day-to-day driver and vehicle man-

sion of JSE listed Cargo Carriers, has

management, invoicing and proof of deliv-

agement issues but also ensure that

installed its FleetLogiX software system

ery, among a host of other productivity

transactional data is accurately recorded

to manage a fleet of 1 000 Volvo trucks in

and profit-geared features.

and reported. The FleetLogiX and OnKey

Ethiopia for Derba MIDROC’s subsidiary, Derba Transport.

In addition to the FleetLogiX system deployment, CargoWare will install Onkey,

Initially 750 trucks were used to collect

a maintenance management system which

imported cement from a seaside port

enables transport operators to control

in Djibouti and deliver it to an Ethiopian

the maintenance of all assets and and

cement plant under construction just

to manage service and repair schedules.

70Km from Addis Ababa. The new plant

“Our history tells us that companies

will be sole cement provider to the $4.8Bn

which use our full suite of transport

Grand Ethiopian Renaissance Dam project.

solutions can shave in excess of 10%

The plant will produce three million

o f f t h e i r o p e r a t i o n a l c o s t s,” s a y s

tons of cement annually; for the Grand

Charel Schickerling, general manager at

Renaissance Dam and to meet domestic

CargoWare and the executive responsible

and neighbouring country demand. It will

for the Ethiopian project.

be delivered by Derba Transport’s fleet,

Per Ljungstrand, general manager –

which will number 1 000 trucks in the

Derba Transport says the challenges of

coming months.

managing such a large fleet can simply not

Fleet operators typically use FleetLogiX to schedule vehicle movements, manage dispatch and driver allocation,

systems provide these controls and allow for future expansion.”

be addressed without a computerised fleet management system.

“Such a system should not only deal

Charel Schickerling, general manager at CargoWare.

PRECAST CONCRETE TOILETS FOR AMATHOLE COMMUNITY Against a backlog of 180,000 toilets, the

cluding concrete curing. The concrete pan-

district municipality of Amathole, a very poor

els, which are light and easy to handle, are

structures to be erected in 15 minutes.

“Only six concrete panels are required

and rural part of the Eastern Cape, issued

manufactured with hand grips, enabling top

for a complete structure which offers a

a tender for concrete panel toilets. The

relatively large interior (900mm wide x

first phase was won by CMA member, Rocla

1 10 0 m m d e e p x 2 0 0 0 m m h i g h ),

Sanitation, which has delivered 17,500 of

conforming to all relevant standards and

the 25,000 toilets required by June 2014.

offering the safety of a dual locking system

With an average concrete panel

(ie toilets can be opened from the inside

weighing 102.5kg, and a complete toilet

when locked from the outside).

weight of 705kg, approximately 17,875

“The community, we believe, are happy

tons of concrete panel toilets have been

with the aesthetics of the toilet struc-

supplied by Rocla, the company’s largest

tures. A second tender is currently in the

single such project to date.

adjudication phase, and we are extremely

Simon Wells, business manager: sani-

optimistic of our ability to be successful

tation at Rocla said “The project, which

with this second phase.

is being funded under the Municipal Infra-

“This is a huge step forward for the

structure Grant Programme, has created

community who in the past had no access

employment opportunities for locals in

to clean water or hygienic sanitation”

a dedicated factory which we opened in

said Wells.

2011. It will remain operational until the

Contact Malebusa Sebatane, Marketing

project is completed next year.”

M a n a g e r, R o c l a Te l: 011 6 74 6 9 57

“All things being equal, it takes 10 days from manufacture to final installation, in-

PRECAST VOLUME 8 • ISSUE 1 • 2014

Cell: 078 803 9863 email: malebusa.

One of the Rocla toilets in Amathole.

sebatane@murrob.com

APPLICATIONS

31

AFRISAM HELPS WINDFARM ACHIEVE FAST TURNAROUND TIMES T he 138MW Jef freys Bay Wind Farm

foundations, but one which would also

is characterised by the extremely fast

expedite the project due to its rapid

track nature of the project. A consortium

hardening properties. The cement is cost-

for the provision of civils and electrical

effective due to its workability, strength

infrastructure to one of the continent’s

and dur abilit y pr oper ties,” Mer edith

largest wind farms was formed by

Jordan, AfriSam sales manager: Building,

two Murray & Rober ts Construction

Civil and Manufacturing (BCM), explains.

companies, Concor Civils and Concor

“Delivery of 4 000 tons of cement ran

Roads & Earthworks, in a joint venture

from March to December 2013. The bulk

with Consolidated Power Projects (Conco).

of the product was sent from our Ulco

Murray & Rober ts Construction’s

factory, some 80 km from Kimberley.

p o r ti o n o f th e p r oj e c t in clu d e d th e

This equates to a lead distance in the

construction of 50km of gravel road,

order of ±1 000 km each time we made

60 concrete foundations for the wind

a delivery. Our depots in Queenstown and

turbines, route modifications on the N2

East London were placed on standby as

highway, the building of an operations

a backup and we made all our deadlines,”

building, as well as trenching for 200km

Jordan points out.

of MV cabling to the substation.

Nell says that the civils and electrical

Each of the turbine foundations required

infrastructure project consortium was

approximately 335m3 of concrete and the

given ten milestone dates with which they

selection of a suitable cement supplier was

needed to comply.

based on a number of factors.

“We were under extreme pressure

“We chose Af riSam due to our

but we have managed to meet the first

longstanding r elationship with the

nine milestones timeously and we are on

company, the quality of the cement, its

track to achieve the final deadline in the

suitability for the project, the pricing and

first quarter of 2014. The expeditious

its ability to deliver on time,” Joe Nell,

cement delivery played a large role in the

project manager for the consortium, says.

successful attainment of the foundation

The wind farm’s civils and electrical

deadlines.”

in f r as tr uc tur e c onsor tium sele c t e d

Murray & Roberts’ Concrete Centre of

AfriSam’s HSC 52.5N cement due to its

Excellence developed the optimum concrete

early strength properties.

mix to cope with the high temperatures

“T he customer required a cement

generated beneath the turbines. The mix

which was not only able to provide the

also needed to be extremely durable, so the

high strengths required for the turbine

concrete included a fair quantity of fly ash.

A turbine foundation at the Jeffreys Bay Wind Farm project.

PRECAST VOLUME 8 • ISSUE 1 • 2014

32

APPLICATIONS

TECHNICRETE RETAINING WALL WITHSTANDS MAJOR FLOODS With the potential for flooding along the Vaal River ever present, waterfront properties are at risk of being washed away or damaged. Yet one property, protected with a retaining wall built from CMA member, Technicrete’s Earthform garden blocks in 2009, is still intact, despite the massive floods of 2010 and 2011.

Jannie Odendaal built his house on the banks of the Vaal River between Christiana and Bloemhof in 2009. Realising that the Vaal Dam held up to 2,600 million cubic meters of water upstream, he wisely chose Technicrete’s Earthform walling system to protect his property.

Odendaal said “I am not an engineer and have no technical knowledge on retaining walls, or how to erect them. I selected Earthform, simply because the accompanying pamphlet gave me very easy-to-understand instructions on how to install the garden blocks. Four of us erected a circular six metre retaining wall, three meters from the edge of the water.”

“We knew that we needed some form of drainage, and left 15mm spacings for that. The sand was compacted tightly on the embankment and approximately 2,000 Earthform garden bricks later we had an enormous retaining wall in place. One year later we had the first major flood, and again in 2011 an even greater flood occurred when the sluice gates were opened and 3,400 cubic litres per second were released into the river. Neighbours’ properties were washed away, embankments and other brick retaining walls collapsed – but we were completely intact.”

Although aimed at the DIY market, Technicrete’s Earthform garden blocks are also used by landscaping contractors and property developers. Earthform is a low maintenance product and offers an attractive solution to the creation of garden features and steep retaining walls. They can be stacked up to eight layers high on stable ground and vegetation can be easily planted inside the block. The blocks weigh just 23kg and measure 320mm x 290mm x 180mm.

The retaining wall constructed from Technicrete’s Earthform garden blocks in 2009, is still standing, despite the massive floods of 2010 and 2011 along the Vaal River”.

PRECAST VOLUME 8 • ISSUE 1 • 2014

MEMBERS LIST

33

Producer members A Fick Sementwerke

Concrete Units

Lategan Cement Works

Rocla

Aveng Manufacturing Infraset

Conframat

Marley Roofing

Savanna Bricks & Paving Pty Ltd

Bassbeams

Colonial Stone

Mobicast Pty Ltd

Shukuma Flooring

Bay Brick

Corobrik

Monier Roofing South Africa

Smartstone

Beta Tiles

Deranco Precast

MVA Bricks

Southern Pipeline Contractors

Boland Concrete

Eagle Roof Tiles Pty Ltd

Panda

Style Décor Design & Manufacturers

Bosun Brick Midrand

Echo Prestress Pty Ltd

Technicrete

Namib Roof Tile Company

Brickcast Industries cc

Fastdeck Pty Ltd

Portland Hollowcore Slabs Pty Ltd

Topfloor Concrete Ltd

C.E.L. Paving Products

Inca Masonry Products

ReMaCon Products cc

Vaka Concrete Pty Ltd

Cast Industries

Keystone Walling

Revelstone (Cape) Pty Ltd

Vanstone Precast Pty Ltd

Civilworks

Kwena Concrete Products

Reya Pele Bricks Ltd

West End Cement Bricks Pty Ltd

ILIFA Africa Engineers Pty Ltd

Sekhukune & Associates

Terraforce Pty Ltd

J C Paving Consulting

SNA Civil & Structural Engineering

Tjeka Training Matters

Associate Annual Members ASPASA ARQ Consulting Engineers Pty Ltd British Precast Concrete Federation Concrete Society

Pipeline Installation Professional Engineering

SARMA The Job Club Services

Young & Satharia Consulting Civil Engineers

NON-Producer members Abel Equipment

Kaytech

Ash Resources Pty Ltd

Kerenos Southern Africa Pty Ltd

H Birkenmayer Pty Ltd

Kobra Moulds B.V.

Chryso Southern Africa Pty Ltd

Manitou Southern Africa Pty Ltd Pan Mixers SA Ltd

Doubell Brick Machines

SamJung Industries Ltd

Delta Bloc South Africa Pty Ltd Dick King Lab Supplier

Schlüsselbauer Technology GmbH & Co KG

HawkeyePedershaab

Sika South Africa Pty Ltd

Kavango Block & Brick cc

Techmatik S.A.

Contractor Members Decoroton Retaining Systems

PYW Paving

Friction Retaining Structures Pty Ltd

Valcal International Export

Powergate Construction

CEMENT PRODUCER Members AfriSam South Africa

PPC Ltd

Sephaku Cement

For a full list of contact details, contact the CMA on tel: (011) 805-6742 or email: admin@cma.org.za

PRECAST VOLUME 8 • ISSUE 1 • 2014