Precast • Issue 3 • 2017 by Isikhova Media

ISSUE THREE • 2017

R49.00

THE CMA – QUALITY CAST IN CONCRETE

• Farewell to a legend • SANAS accreditation for CMA CS • Retaining wall failure debate

EIRICH R-TYPE MIXERS + HYDRONIX MOISTURE CONTROL = TOTALLY CONSISTENT CONCRETE WITH EVERY BATCH

HYDRO CONTROLAUTOMATES MIXING A. BATCH IN MIXER B. CEMENT DISCHARGE BY TIMER C. MONITORED FLAT LINE FOR DRY MIX AND MOISTURE MEASUREMENT D. WATER DISCHARGE E. MONITORED FLAT LINE FOR WET MIX F.

TIMED DISCHARGE

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

PRODUCTS

COVER STORY 2

FEATURE

WATER CONTENT MARKS CENTS

26 CRB WALL FAILURE – ANOTHER TAKE

INDUSTRY NEWS 5

CONCRETE MARK OF APPROVAL

OBITUARY: JOHN WILMOT LANE

17 GREEN CONCRETE ON SITE

GLOBAL VIEW

10 CHOOSE MIXING WATER WISELY

12 CONFERENCE UNITES CONCRETE INDUSTRY

15 16 IMPROVED PACKAGING

9 11 ETHICALLY OBTAINED AGGREGATES KEY

TECHNICAL 30 MAINTAINING SA’S ROADS 31 FIRST AID EMERGENCY EQUIPMENT AND PROCEDURES 32 CARBON CONCRETE

PROJECTS 36 PRECAST BEAMS FOR PRESTIGIOUS HOUSING DEVELOPMENT

20 GROWING IN THE UK

37 LIMPOPO ROAD PAVEMENT UPGRADES

ADVERTORIAL

38 MOZAMBIQUE BULK TERMINAL BERTH EXPANSION

22 ROCLA CELEBRATES 100 YEARS OF EXCELLENCE

38 CONCRETE ROOF TILES FOR HOUSING ESTATE 39 CONCRETE BLOCK PAVERS ASSISTANCE 40 PRECAST CONCRETE SPEEDS UP

43 MONEY FOR NOTHING

13 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

COMPANY NEWS

25 PIPE PLANT STREAMLINES PRODUCTION CAPACIT Y 25 PPC COMBATS UNEMPLOYMENT

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

ISSUE THREE • 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:

• Farewell to a legend • SANAS approval for CMA CS • Retaining wall failure debate

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

PMSA solutions improve quality and save money. Manufacturers who carefully control moisture contents throughout their concrete manufacturing cycles can produce concrete of a higher quality, more

consistent and more cost-effectively than those who do not. So says CMA member PMSA’s marketing and sales manager Quintin Booysen, adding that specially designed systems for the precast industry can make a big difference to manufacturers’ bottom line and, in most instances, pay for themselves within a year of installation. Far from being a luxury in tough economic conditions, moisture control systems should, in fact, be regarded as a strategic purchase that gives the manufacturer a considerable edge over less advanced opposition. Quick calculations indicate that the savings are not small and can easily add up to R420 000 per annum on an

MEASURING AND

WATER CONTENT

average-sized brick or block-making plant

als as they are delivered. Inputs via the

and even greater savings on large brick,

devices are either uploaded manually or

paving and block plants. In rooftile, pipe

via hand-held devices and variances can

or manufacturing plants that use spe-

be entered to adapt mix ratios. Suppliers

cialised concrete or where more cement,

can also be notified and invoices amended

oxides or admixtures are used, the figure

to reflect deductions for excess water

can be even higher.

in delivered aggregates.

Losing money

aggregate-to-cement ratio should be

“Manufacturers often don’t fully appreci-

kept constant by taking into account the

ate the importance of controlling water

water which is already in the aggregate.

When batching the aggregates, the

in order to get the moisture contents of a mix right from the start. Beginning

(Above): Microwave probe measuring field.

This is done by adding more aggregate equal to the water weight contained in

with sand and aggregates, some manu-

the usage of cement and admixtures. So

the aggregate to correct for the water,

facturers pay up to 10% of their overall

every ingredient therefore needs to be

thus achieving the perfect aggregate-

bill just in excess water. If the moisture

carefully measured and controlled – and

to-cement ratio. The measurement of

content is supposed to be 5% and is 15%

water in the process is no different.”

the moisture in the aggregates is done

when delivered, they’re evaporating their profit,” says Booysen.

using the Ludwig Moisture Probes on the Precision instruments

feed belts or in the cone of the aggre-

“This is only the beginning of the

PMSA has therefore worked tirelessly

gate chute directly where the materials

problems, as the extra water will also

to assist manufacturers to find seam-

are being weighed. Once again, extreme

throw their mix ratios out, which will

less solutions to monitor and control

accuracy is required and Ludwig has a

have a knock-on effect throughout the

moisture through each cycle of their

wide range of microwave sensors which

entire process and will either considerably

plants. Together with German manufac-

can be mounted in suitable holders to

increase the amount of cement used or

turer Ludwig Moisture Control, they have

give the plant foreman – and PLC, on

reduce the strength of their products. In

brought to market a number of solutions

addition, it may lead to changes in the con-

which are suitable for local conditions.

sistency of the concrete, causing sticking

These include measurement systems

on tools or variances in curing times, etc.

that are tailor-made for every step of

“Of course, as everybody in the in-

the production process, starting in the

dustry knows, variances in consistency

raw material stockpiles. Here specially

and quality are the biggest enemies of

developed Ludwig FL-Profi Check micro-

production, as they slow the process

wave sensor probes are used to get an

down, lead to more wastage and push up

instant moisture reading on raw materi-

“Savings can easily add up to R420 000 per annum on an average-sized brick or block-making plant.” PRECAST | ISSUE THREE | 2017

COVER STORY 3

D CONTROLLING

T MAKES CENTS the batching side of the plant – the op-

design,” explains Booysen.

accuracy. Furthermore, it provides full training, support, servicing and programming of the systems. With more than 20 Ludwig Moisture Measurement and Control systems installed in SA, in large plants ranging from piping to roof tile, brick and block manufacturing, the existing clients are without fail experiencing full returns on

portunity to check and adjust mixes in

This information is then fed into the

their investments within a year or less

accordance with the moisture contents

batch control PLC of the plant and the

after installation. “In most instances,

of the aggregates.

final completed mix inside the mixer is

our clients with multiple plants have

checked via the final moisture measure-

quickly come back and asked us to roll out

Continuous readings

ment before being discharged into the

systems across their network of sites,”

And this is not the last time the sen-

roof tile, brick, block or pipe-making

says Booysen.

sors are used. A further set of sensors

machine hopper.

(Top, from left): Ludwig moisture probes are available in a number of varieties for different applications.

mounted in the mixer itself is able to give

“Feedback from the mixer probe is

up-to-the-second readings of moisture

continuously checked until the consist-

in the final mix to ensure it is exactly as

ency is exactly right or fine water doses

required. PLC controls usually mean that

are added through measured water pulse

Reason to invest

dosing is automatic and, depending on

meters to get it precise every time. With

An indication of the value of moisture

requirements, it can be adjusted immedi-

exact measurement, the right amount of

control can be seen in the following

ately and on the spot to ensure concrete

materials such as water, aggregates, ce-

calculation:

is consistent with requirements.

ment, oxide and admixtures is used, which

Let us assume that a plant pro-

“Through the initial aggregate mois-

ensures not only consistent strength, but

ducing 80 000 rooftiles can save

ture measurement, the PLC knows how

also consistency of colour,” says Booysen.

just 5% cement due to correct

much water is initially being added via

moisture control. If each tile weighs

raw materials. Then process water can

Upgrades available

4,5kg, then the entire output will be

be added precisely and adjustments

He adds that even non-PMSA plant

360 000kg, of which 20% is cement.

made so that dosing systems add the

equipment can be upgraded to cater for

That means 288 tons of aggregates

correct amount of dosed water to

precise moisture control in both fixed-

and 72 tons of cement. An additional

ensure the water-to-cement ratio is

drum mixers and counter-current mixers

5% (which is 3,6 tons per day, or 800

perfect and in accordance with the mix

with rotating drums. The company offers

tons per annum) can be saved just by

assessments of plant and will make sug-

controlling cement. At R1 150 per

gestions on the type of controllers and,

ton of cement, this equals R920 000

if necessary, the PLCs required, as these

per annum and easily pays for the

can either be replaced or upgraded to

system in under a year. Additional

accommodate the system.

savings are made through more

It will also manage and undertake

consistent colour, production and

the complete installation of all required

fewer reject batches of concrete

systems, as well as the calibration of

mix and tiles.

equipment to ensure the best possible

PRECAST | ISSUE THREE | 2017

Through its continuing pursuit of excel-

creditation pertaining to specific product

• SANS 677 – Non-Pressure Pipes

lence in precast concrete, the CMA CS

groups, we can confidently certify most

• SANS 927 – Kerbs and Edgings

has obtained SA National Accreditation

precast product types that are required

• SANS 986 – Reinforced Culverts

Services (SANAS) accredita-

to meet SANS specifications.

tion for the certification of

“In future, all CMA CS Mark

a wide range of precast con-

of Approval certificates will

crete products.

bear the SANAS number (C75)

• SANS 1058 – Paving Blocks • SANS 1215 – Masonry Units • SANS 1294 – Manhole Components

The certification puts it

and logo on it and we’ll re-issue

Rest assured

in the forefront of precast

new certificates to the current

For the end-users of precast products,

certification and ensures that

mark-holders in due course.

the CMA CS mark of approval ensures

specifiers and engineers can

The best thing about our mark

that the company producing products

specify products bearing the

is that it’s internationally ac-

under it is being assessed on a regular

CMA CS Mark of Approval with

cepted, meaning we can also

basis for compliance with its quality

provide services outside the

management systems, as well as the

borders of SA.

applicable product specifications for

the utmost confidence. Products bearing that mark are

(Above): Frans Minnaar of the CMA.

certified to comply with requirements

“We’re happy to inform those pro-

prescribed by the relevant SA National

ducers who were concerned and are

“Our CMA CS system auditors are

Standards (SANS) code.

still struggling to obtain new permits

all carefully selected and approved be-

which it has the mark.

CMA CS was established by the pre-

or renewals from the

fore they’re allowed to

cast industry association as an alterna-

SABS that the CMA CS

perform product audits.

tive supplier to the traditional SABS

is now available to issue

Likewise, our permits

certification process, following ongoing

cer tificates with the

are only issued to pro-

complaints from its members and their

SANAS Accreditation

ducers that meet all the

customers about unwarranted delays in

number and logo on it

obtaining and renewing product certifi-

in the same manner as

cations. The CMA CS was subsequently

any other accredited certification body.

ever, end-users should take the time to

registered and obtained accreditation as

They have the added assurance that we’ll

ensure the validity of any mark certificate

an official certification authority.

always maintain the highest standards

by confirming the permit number on the

for our certification services,” says CMA

‘Mark-Holder’s List’, which is published on

CS CEO Frans Minnaar.

the CMA website [www.cma.org.za] before

Going strong “Since then, we’ve undertaken a number

necessary requirements (Above): The CMA CS Mark of Approval.

SANAS certification has been obtained

INDUSTRY NEWS

CONCRETE MARK OF APPROVAL GAINS GROUND

for compliance. How-

acceptance. The CMA CS Mark of Ap-

of audits and provided several companies

for the following product categories:

proval is the mark you can trust for real

with product category certifications.

• SANS 508 – Retaining Blocks

compliance with SANS specifications,”

Now, with the addition of SANAS ac-

• SANS 542 – Roof Tiles

says Minnaar.

“Stopping advertising to save money is like stopping your watch to save time.” – Henry Ford

DON’T MISS OUT! ADVERTISE IN OUR NEXT ISSUE.

Contact Wally Armstrong on tel: 083 701 3278 or e-mail: WallyArmstrong@Outlook.com

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

John was born on 29 January 1924

John was a deputy-director of the Rho-

the 190mm wall, as until then, the mini-

and, after suffering a stroke, passed

desian Portland Cement Institute (PCI)

mum wall thickness had been 210mm; it

away on 18 July 2017 at the age of 93.

(1959-1964) and from 1965-1975 the

took him two years to get the 190mm

The youngest of four brothers, he was

director of the Portland Cement Institute

block approved.

a direct descendant of 1820 settler

Central Africa (Bulawayo), from which he

When he joined the CMA, the inter-

Joseph Wilmot Lane. His early infancy

worked on projects in Zimbabwe, Zambia,

national masonry and paving industries

was spent in Parkview, Johannesburg,

Malawi and Botswana. During this period,

were considerably more advanced than

where he landed in trouble for swimming

he was also appointed president of the

their local peers. John established strong

in Zoo Lake with his brothers.

Rhodesian Institution of Civil Engineers.

ties with peer associations in Australia,

His childhood was spent in Port Eliza-

He returned to SA in 1975 and joined

New Zealand, the UK and the USA, which

beth, where he attended Grey College

the Portland Cement Institute as deputy-

resulted in cross-memberships with the

from kindergarten to matric. He loved

director, a position he held until 1985.

National Concrete Masonry Association

sport, particularly rugby, and swam and

of the USA and the Concrete Masonry

dived for Grey College. His parents moved

Association of Australia.

to Natal (now KwaZulu-Natal) while he was still at school and he matriculated

International appeal

at a very young 15.

International experts were invited to

After school, he relocated to Johan-

some of the CMA’s conferences, and

nesburg, where he worked for a year

local producers benefited enormously

before enrolling for a civil engineering

from these ties. John and CMA members

degree at the University of the Wit-

also travelled to Australia, Europe and

watersrand (Wits). His love of rugby

the USA, attending conferences and

endured at Wits and he played hooker for

gaining invaluable knowledge of precast

Transvaal Under-19. Graduating with a

concrete technology.

BSc civil engineering degree in 1943, he

John collaborated with one of the

extended his studies to town planning,

world’s leading concrete block paving

gaining a diploma. In 1952 he was one of

experts, Dr Brian Shackel of the Uni-

two South Africans selected in a Com-

versity of New South Wales, Australia,

monwealth programme to study town

who became a close friend. Their wives

planning at MIT in Boston, USA.

also formed a close bond and both were New challenge

members of the Black Sash.

Early days

Aged 61 and close to retirement, John

Shackel spent several years in SA

In 1954 John settled in (then) Southern

was approached by the Concrete Ma-

at the Council for Scientific & Industrial

Rhodesia (now Zimbabwe), where he

sonry Association (CMA, forerunner of

Research exploring various pavement

joined a civil engineering contractor,

the Concrete Manufacturers’ Associa-

designs, including concrete block paving,

N Stipinovich. One of his initial projects

tion NPC) and offered the position of its

and the results formed the basis for the

was a water treatment and sewerage

first full-time director. His appointment

SABS standard in the manufacture and

plant in Wankie (now Hwange) and he was

flowed from a realisation that using a

application of these blocks. His input had

the project leader in the construction of

neutral and technically proficient body

a profoundly positive impact on the local

the Bulawayo airport in 1959. In 2016,

such as the CMA would enable local

paving industry and transformed SA into

his grandchildren landed on the runway

masonry and paving block producers

a world leader in concrete block paving

which John and his team had built 57

to promote the enormous potential of

technology – a status it still enjoys.

years before.

precast concrete products through the

He met his wife, Elizabeth (Bette) Walker, at a party held to celebrate the

production and widespread distribution

Global leader

of technical literature.

John enjoyed world renown in concrete

completion of the water treatment plant.

Thanks to his strong academic back-

masonry and several generations of

She was one of several young women who

ground and vast knowledge of concrete

technikon and university students ben-

were invited from the local school and

technology, John transformed the CMA

efited from his written material and

hospital to enliven the event, which would

into an internationally respected asso-

lectures on cement and concrete ma-

otherwise have been a dour bachelor af-

ciation with a strong technical bias. One

sonry. Quietly spoken, he was widely

fair. Born and raised in Scotland, she had

of his first initiatives was the establish-

respected for his insatiable curiosity,

come to Africa on a teaching programme.

ment of SABS specifications for the

his boundless enthusiasm and his formi-

The couple were married at the Bulawayo

production of concrete masonry blocks,

dable intellect. Moreover, he was always

Catholic Cathedral in 1958 and both their

followed shortly by a SABS standard for

professional and meticulous in his ap-

children were born in that city, Susan in

concrete paving blocks. Another of John’s

proach and gave of his time generously,

1962 and Neill in 1960.

early enterprises was the acceptance of

especially to students.

PRECAST | ISSUE THREE | 2017

INDUSTRY NEWS

OBITUARY: JOHN WILMOT LANE (1924-2017)

INDUSTRY NEWS 8

He worked tirelessly on numerous

Home Building Manual and various Joint

technical and SABS committees to

Structural Division publications. Besides

He was the recipient of a 40-year

further the science and technology of

the CMA’s masonry manual, he was the

Institution of Structural Engineers ser-

concrete masonry and wrote several pub-

editor and co-author of Build Your House

vice award and, in 2004, was presented

lications in this regard. These included

Step-by-Step, Detailing of Concrete Ma-

with the SAICE President’s Award for

an extensive CMA manual on concrete

sonry Structures, the CMA’s Paving Block

meritorious service to that institution

masonry, which ran to over 100 pages.

Manual, Structural Concrete (a design

for “significant ongoing contributions to

Generally regarded as the definitive au-

guide) and Structural Concrete Masonry:

the civil engineering profession”.

thority on concrete masonry, it is now in

A Design Guide (2000). He was also the

After retiring from the CMA in 1992,

its ninth edition.

author of The Manufacture of Concrete

he continued to lecture and sat on several

Masonry Units (1997).

committees. He assisted with revisions

In addition, he authored and co-

SABS technical committees.

authored several international publica-

He was a scrupulous editor who al-

on various publications, wrote articles and

tions and contributed to the National

ways ensured that his written output

participated in seminars and conferences,

Homebuilders’ Registration Council’s

was absolutely correct, both technically

both for the CMA and SAICE.

and grammatically. This is one of the rea-

John and Bette moved to Elphin Lodge

John enjoyed world sons that his publications, as well as the Retirement Village in Johannesburg in leaflets and instructional film material to 2007. After 56 years of marriage, she renown in concrete which he contributed, are still referred to died in 2014. by professionals and contractors. John is survived by his son Neill, masonry and daughter-in-law Karoline and his grandchildren, Charlotte and Harold. several generations Other roles Besides his work for the CMA, John was He was much admired by Elphin Lodge of technikon and chairman of the SA Institution of Civil residents for his old-world courtesy. Al(SAICE’s) structural divithough his eyesight had deteriorated due university students Engineering sion in 1983 and chairman of the joint to the onset of macular degeneration, he benefited from his structural division’s standing committee remained active to the last, attending onuntil structural masonry for many years. Please a weekly exercise class before Final material will not be supplied for print/publication such time as approval is received. return fax to: 086the 509day 4850 written material. He was also an active participant in the his stroke.

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INDUSTRY NEWS 9

PRECAST CONCRETE AT ITS FINEST Entries are in for one of the biggest

as the professional stage on which the

ing techniques, condition of the installa-

events on the construction industry

awards are presented.

tion, condition of the precast concrete

calendar next year, in the form of the

“That’s why judging for the event is

Concrete Manufacturers’ Association

designed specifically around set cat-

and performance of the product. Sponsored by PPC, Afrisam, ASPASA,

(CMA) Awards for Excellence.

egories. For the 2018 event, the entry

Aveng and Chryso, the 2018 CMA Awards

Every two years, manufacturers in

categories were reformulated to provide

for Excellence will be a glamorous event

the precast concrete industry present

a better spread of awards for each pre-

befitting its high esteem within the con-

their very best work for judging against

cast product type and size. This ensures

struction industry. It will be held at The

peers in various categories. These are

we compare ‘apples with apples’,” says

Venue in Melrose Arch, Johannesburg, on

scrutinised by a panel of recognised pro-

Cockcroft.

the evening of 24 March 2018.

fessionals, who judge the entries against

The two main pillars of the awards are

a strict set of criteria designed to make

“Aesthetic Excellence” and “Engineering

FAST FACTS -

the process as fair and transparent as

Excellence”. Each of these pillars has

This year’s judges

possible.

three judges who are experts in that

Over the years, the CMA Awards for

particular field. For instance, “Aesthetic

Aesthetics

Excellence have recognised newly-built

Excellence” has a landscape architect, an

• Eamonn O’Rourke, president:

projects that later became landmarks

architect and a civil engineer as judges,

Institute for Landscape

for the country and benchmarks for the

while “Engineering Excellence” has a civil

Architecture in SA

engineering and architectural profes-

engineer, a structural engineer and a

• Kevin Bingham, president:

sions. CMA marketing manager, Henry

contractor as judges.

SA Institute of Architects

Cockcroft, says the 2018 awards will

• Prof James Maina, Faculty of

once again showcase the best-of-the-

Separate criteria

Engineering, Built Environment

best in the use of precast concrete in

The criteria for judging include the ap-

& Information Technology:

southern Africa.

pearance and enhancement effect of the

University of Pretoria

“Despite the decline in building and

precast product on the overall project,

infrastructure activities, we’ve received

detailing, quality of the installation,

Engineering

a similar number of entries as we did

product quality, condition of installation,

• Prof James Maina, Faculty of

for the previous event and will require

structural integrity, age of project and

Engineering, Built Environment

all hands on deck when the judging is

the environmental conditions causing

& Information Technology:

finalised in mid-November 2017. Due

wear or erosion for aesthetics alone.

University of Pretoria

to advancements in materials, design

Engineering excellence has its own

• Prof Mitchell Gohnert, School of

elements and technology, we certainly

equally tough criteria, including the engi-

Civil & Environmental Engineering,

expect to see some leaps forward and

neering excellence achieved with product/

University of the Witwatersrand

look forward to discussing these in more

project, best practice applied, installa-

• Bonke Simelane, president:

detail on the night of the awards.

tion functionality, innovation in design,

Master Builders SA

application, installation and manufacturImproved format “The quality of the entries is directly affected by the status of the Awards for Excellence, as they’ve grown over the years and entrants are aware that they’re being monitored externally by engineers, consultants, architects and contractors. This contributes to the quality and number of entries, as well

PRECAST | ISSUE THREE | 2017

INDUSTRY NEWS

• Seawater or brackish water: This

water may be used for concrete

withou t r einf or cement or o ther

embedded metal, but is in general

unsuitable to produce reinforced or

pre-stressed concrete. For con-

crete with steel reinforcement, or

with embedded metal, the permitted

total chloride content in the concrete

should be the determining factor.

• Sewage water: This water is unsuit

able for use in concrete.

• Chloride content: In general, the

chloride content of the water for

pre-stressed concrete or grout must

not exceed 500mg/litre; for concrete

with reinforcement, the maximum is

1 000mg/litre and for concrete with-

out reinforcement or embedded metal,

it is up to 4 500mg/litre.

• Sulphate content: The sulphate con

tent of the water should not exceed

2 000mg/litre.

• Alkali content: If alkali-reactive agg

regates are to be used in the

concrete, the water must first be

tested for its alkali content. The equiv-

alent sodium oxide content of the

water should not normally exceed

CHOOSE MIXING WATER WISELY

fects. It’s recommended that water of

1 500mg/litre.

unknown quality be evaluated in terms

• Harmful contamination: Qualitative

of the methodology in SANS 51008.

tests for sugars, phosphates, nitrates,

When assessing the suitability of water

lead and zinc should be carried out.

The Concrete Institute (TCI) has cautioned

concrete, both the composition of the

Test carefully

concr ete manuf actur er s to select

water and the application of the concrete

Perrie adds that the initial setting time

mix water carefully, as its quality can

to be produced should be considered.”

obtained on specimens made with un-

(Above): The quality of the mixing water in concrete can influence its setting time and strength.

of unknown quality for the production of

influence the setting time and strength

known water should not be less than an

development of concrete, as well as

Fit-for-purpose

hour and not differ by more than 25%

the protection against reinforcement

Perrie says the suitability of water to

from the initial setting time obtained

produce concrete depends on its

on specimens made with distilled or de-

corrosion. Bryan Perrie, MD of TCI,

origin. The following types may

say s tha t w i th the high

be distinguished:

levels of contamination of

• Potable water: This water is suit-

water r esour ces f r om

able and needs no testing.

ionised water. “The mean compressive strength at seven days of the concrete or mortar specimens prepared with the water

industrial processes, not

• Water recovered from pro-

should be at least 90% of the mean

all natural waters found

cesses in the concrete indus-

compressive strength of corresponding

in SA are suitable as mix-

tr y: T his water is normally

specimens prepared with distilled or de-

ing water. “It’s commonly said that

suitable for use in concrete, but

ionised water,” he says.

if water’s potable, then it’s suitable

must conform to the requirements

for concrete. But water that’s not

SANS 51008 provides test methods

of SANS 51008.

for the tests required, applicable fre-

potable may still be satisfactory

• Wa t e r f r o m un d e r gr o un d

quencies for testing and detailed require-

for making concrete, as long as the

sources: This water also needs to

ments for the use of water recovered

be tested and assessed in accordance

from processes in the concrete industry.

quality and chemical composition remain constant to avoid unexpected effects on

with the requirements of SANS 51008.

TCI recommends that these methods be

the concrete,” he says.

• Natural surface water and indus-

studied and complied with to ensure that

“Turbid water should be allowed to

trial waste water: This, too, must

the water component of the concrete

settle before use to remove suspended

be in accordance with SANS 51008

mix will not negatively affect the quality

solids which could have unexpected ef-

stipulations.

of the concrete.

PRECAST | ISSUE THREE | 2017

INDUSTRY NEWS

So-called “green” precast products cannot truly be sustainable unless the aggregates used in the manufacture of the concrete is procured from quarries that uphold strict sustainability and environmental policies. This is according to Nico Pienaar of aggregates and surface mining industry

association and CMA member Aspasa, who explains that every year billions of tons of aggregates are extracted around

ETHICALLY OBTAINED AGGREGATES KEY TO SUSTAINABILITY

the world to build roads, dams, hospitals, schools, private homes and a myriad of other structures which are essential to the development of our planet. As a result, aggregates are by far the most widely used bulk material on earth, with demand growing apace with expanding urban populations. However, the potential for large-scale damage to the environment demands that all aggregates

(Above): Green aggregates.

should be procured from ethical suppliers who can prove their credentials.

4. Working within the confines of legisla

tion and ensuring consistency of

Better way

enforcement of the law and a level

In SA, the most reliable means of ensur-

playing field among both members and

ing ethical supply is to deal with Aspasa

non-members. Working with legisla-

member quarries, which are required

tors to modernise legislation, cut red

to uphold strict environmental require-

tape and promote a profitable and

ments and pass annual audits based on

thriving industry in support of the

ISO14001 standards. These aggregates

country’s future development goals.

are obtained from sources where suit-

5. Promoting responsible extraction

able geological deposits occur, rather

of minerals and working with interest

than being randomly excavated near

groups, research centres, universi-

construction sites.

ties and other interested parties to

Furthermore, procuring materials

overcome environmental challenges in

from these companies ensures stable

areas that may be deemed sensitive.

and sustainable jobs for workers who

6. Encouraging social participation and

are employed within the confines of the

(Above: Nico Pienaar of Aspasa.

open lines of communication with

law in a safe environment, as prescribed

training member companies to work

surrounding communities and other

by Aspasa health and safety standards,

safely in pursuit of zero harm to all

stakeholders. The aim is to leave a

and the companies are also subject to

emplo y e e s, c on tr ac t or s, sub -

legacy that empowers the community

an annual audit, in line with international

and its people.

standards.

2. Realising that quarrying is a tempo-

7. Developing communication tools and

contractors and visitors.

A healthy and profitable formal aggre-

rary land use and minimising damage

public relations training for staff so

gates industry is essential to the con-

to the environment. At the end of the

that stakeholder concerns can be

struction industry and adds value to the

land use, ensuring that it is returned

raised, documented and dealt with in

entire construction supply chain. Apart

to being a fully functioning ecosystem

from government legislation, Aspasa

or is rehabilitated in line with future

represents the only formal regulation of

land use objectives.

the industry, without which it would prob-

3. Promoting a circular economy in which

tainability, while still ensuring that it’s

ably become swamped by roadside and

maximum efficiency is sought in all

able to meet demands of the industry,

unscrupulous operators who pay scant

stages of the life-cycle of the quarry, in-

as well as the overall development plans

attention to any laws or standards.

cluding optimal extraction, production

of the country. It’s true that we can’t do

and transport in the closest possible

without aggregates and, for this reason,

Seven pillars

proximity to the end-user market. The

we’re working tirelessly with the indus-

By comparison, Aspasa measures sus-

local economy is supported in recycling

try to ensure that we can extract and

tainability by:

and making use of all available re-

produce them in the most sustainable

1. Regulating, raising awareness and

sources as far as possible.

manner,” says Pienaar.

PRECAST | ISSUE THREE | 2017

a transparent manner. “Aspasa is seeking to move the entire

aggregates industry towards true sus-

INDUSTRY NEWS 12

CONFERENCE UNITES CONCRETE INDUSTRY S A’s c on cr e t e or ganis a ti ons h a v e

As a result, there is fiercer competi-

and balances throughout the industry,

emerged from a first-ever, industry-wide

tion within the entire construction sup-

the leaning towards sub-standard prac-

conference united and better equipped

ply chain. This is a healthy sign, but could

tices needs to be avoided at all costs.

to deal with challenges facing the con-

also lead to price-cutting that results

The conference, sponsored by Af-

crete and construction sectors.

in less focus on quality of materials and

r isam, Sephaku, PP C and L a f ar ge,

workmanship. Without proper checks

therefore cut to the heart of many of

This is according to organiser Johan van Wyk, of the Southern Africa

the issues and raised concerns among

Readymix Association (Sarma), co-host

the multi-disciplinary audience. Further,

of the event along with the Concrete

it focused on excellence by highlighting

Manufacturers’ Association (CMA), The

award-winning projects through in-depth

Concrete Institute (TCI) and Concrete

technical case studies. These proved

Society of Southern Africa (CSSA). He

that even in the face of tough economic

adds that the event also served to unite

conditions, innovation and design excel-

concrete industry role-players with the

lence can overcome challenges and lead

broader construction and civil engineer-

to the construction of noteworthy con-

ing industry.

crete landmarks.

“In future, we need all professional bodies in the construction sector to

High-performance concrete

work together for the greater good of

“Concrete is by far the most commonly

the industry. That’s why we included

used building material on earth and is

professional bodies from the civil and

the binding ingredient that runs through

consulting engineering fraternity, con-

all our industries. Quality concrete used

tractors, cement producers, builders

in the right applications is essential for

and other role-players to address chal-

construction and it’s vitally important

lenges and form opinions on the way

that all professionals are kept abreast

forward in challenging times.”

of developments in this material,” says Van Wyk. “Rapid urbanisation is driving the

Tough times With the construction industry suffer-

development of new concrete material

ing the effects of a lacklustre economy

and techniques to enable ever-faster

and failing business confidence, trends

construction of larger, taller and more

suggest that it will remain under pressure for the foreseeable future. Political uncertainty has recently also led to a number of construction projects either being cancelled or postponed until political and business confidence returns to the market.

(Above, from top): Richard Tomes underpinned the value of co-operation between professional bodies in the concrete and related industries; CMA marketing manager Henry Cockcroft with CMA accountant Charlotte Swanepoel at The Concrete Conference. (Below): Delegates from across the construction industry attended The Concrete Conference recently.

complex structures. At the same time, challenges are emerging because of skills shortages and cost pressures, which places stress on the entire industry, from the cement producers to the concrete manufacturers, contractors, engineers etc. “The timing of the conference was therefore perfect and these role-players had the opportunity to communicate and network, while also using this platform to share best practices. Without industrywide co-operation, we can’t hope to successfully meet these challenges. I imagine that this is the reason why the conference was able to attract over 300 professionals from a diverse array of backgrounds.” Flourishing together Richard Tomes, chairman of TCI, also suggests that the theme of the conference, “Unlocking High-performance Concrete”, was particularly relevant this year because unless companies continue

PRECAST | ISSUE THREE | 2017

that users are protected. The profes-

of the other bodies. The kind of co-

see our infrastructure begin to fail.

sional bodies in concrete, as well as

operation shown between the concrete

“Each company, in each sector of the

broader construction organisations, have

organisations is therefore an important

construction industry, must therefore

a role to play in self-regulating, testing

step in the right direction and shows

do its bit to uphold quality and speak out

and furthering transparency in their own

we’re making progress in the fulfilment

where it isn’t being advanced. My chal-

specialised areas. In this way, we can

of our combined duties to further the

lenge to you, as civil society, is therefore

consolidate our efforts going forward.

use of quality, fit-for-purpose concrete,”

to self-govern and work together in order

adds Tomes.

to do things right and flourish together,”

First steps

says Tomes.

Planning has already begun for the

“We need neutral industry authorities

next instalment of the conference, which

“We must therefore ensure that we

and we must ensure that we consolidate

is expected to become an important

gravitate towards quality to uphold and

our efforts so that we aren’t duplicat-

fixture for construction professionals

support professional bodies which act in

ing work or wasting resources on work

with interests in concrete. The dates

the interest of the industry and ensure

that’s already been carried out by one

and venue have yet to be announced.

WELCOME TO THE NEW MEMBERS Over the past few months, a number of

fast delivery times. The company runs

well-known companies have joined the

its own fleet of 20 Mercedes-

Concrete Manufacturers’ Association

Benz trucks with the latest

(CMA) to share in the many benefits and

crane technology, able to

mini maxis and hollow blocks).

show their customers that they uphold

deliver various load size

All its products are manu-

the strictest standards and ethics.

requirements. It is also

factured according to strict

They include:

environmentally friendly,

SANS1058-2012 standards

m anu f a c tur ing w i th r a w materials which are recycled.

wide range of precast kerbs. It also manufactures masonry products (cement stock bricks, maxis,

for concrete paving units, SANS1215-2008 standards for its masonry products and

Vibro Bricks & Paving

SANS927-2013 for its precast kerbs.

Seeking further expansion, Laudiumbased Vibro Bricks entered into a joint venture with Savanna Bricks & Paving five years ago to form powerhouse Vibro Bricks & Paving. The merger added a potential output of 400 000 bricks per day (pavers and masonry units), as well as precast kerbs to the existing facility where the output of 130 000 bricks per day is achieved with a PMSA Brick It

VB 4X brick press for masonry units.

This brand has become well-known for

This is supplemented by a further 1 600

quality brick products. For more than

squares of quality paving per day using

12 years, the Kempton Park-based busi-

a PMSA VB 4XA machine.

Mpumalanga Brick & Crete

ness has specialised in the production of

The company manufactures a wide

This Ermelo-based company supplies

paving blocks, cement stock bricks and

range of paving products, as well as a

a wide range of masonr y concr ete

maxi bricks. Its products have been used

products such as stock bricks, maxi

on projects for fine residential develop-

bricks, hollow blocks and pavers. With a

ments, homes, industrial buildings and

sales and manufacturing plant situated

office parks. Owners Steven Carr and

only 12km apart, sales are seamless

Sean Cameron have over 20 years’ expe-

and the company uses its fleet of crane-

rience in manufacturing these products

equipped truck trailer rigs to deliver

and use state-of-the-art manufacturing

to clients’ sites wherever they may be

machinery. “We pride ourselves on our

within the region.

quality and service and our products exceed SANS standards,” says Carr.

Fr om enquir ies and or der ing to delivery, Mpumalanga Brick & Crete

Brick It is able to manufacture over

prides itself on offering a first-class

350 000 bricks per day. Curing cham-

ser vice based on uncompromisingly

bers ensure top-quality products and

high ethics.

PRECAST | ISSUE THREE | 2017

INDUSTRY NEWS

to advance standards, we will eventually

PRODUCTS 15

“LuminTech application merely calls for the particles to be placed on the concrete surface. It also requires no manual input to ‘switch on’ and just needs conventional decorative concrete maintenance: washing the surface occasionally with soapy water. Even in daylight, the particles offer designers creative potential: the choice of daytime colours differs from the colours glowing in the dark.”

GLOW-IN-THE-DARK CONCRETE

Alternative aggregate

CMA member Chryso Southern Africa

Watch-the-step

in conjunction with a water-based sur-

has launched a new product that adds

“The innovative technology can be used to

face retarder. The luminous particles

an attractive, luminous glow to concrete

illuminate and enhance the architectural

are also suitable for polished concrete

surfaces after dark.

lines of an urban building at night, or high-

surfaces, although this application is

LuminTech, the impressive latest addi-

light a domestic terrace or garden path-

not widely used.

tion to Chryso’s range of decorative con-

way, or the edges of a swimming pool. The

“For a building industry increas-

cretes, comprises a variety of different

intensity of the illumination depends on

ingly concentrating on sustainability,

luminescent particles that are applied

the volume of particles scattered on the

LuminTech is an environmentally friendly

to the surface and incorporated into

concrete skin. Available in four colours,

light source, as its particles are sourced

the concrete skin. The particles, which

the particles are ideal for outdoor use, as

from composite recycled material and

imitate natural aggregates during the

they aren’t epoxy-based,” Fick explains.

natural mineral pigments. The new prod-

day, absorb UV radiation, both natural

She says LuminTech’s glowing appear-

uct’s technology meets several French

and artificial, and then release the energy

ance can generally be seen for more than

and European standards and strongly re-

after dark to illuminate selected areas of

10 hours after dark and can be used as

sists impact and friction. It also isn’t af-

a building or home.

luminous nocturnal marking in low-light

fected by freeze-thaw cycles,” she adds.

Fick says LuminTech should ideally be used on exposed aggregate concrete

Michelle Fick, executive relationship

areas, or even replace electric lighting

The durability of the product is said

and project manager for the Chryso

on cycle paths, for example. The lumi-

to be high and its luminosity does not

Southern Africa Group, says LuminTech

nous concrete marking enhances qual-

deteriorate over time.

offers exciting new design possibilities

ity of life, as it clearly defines spaces,

for architects, landscapers and home-

making it easier for users to find their

owners.

way in the dark.

PRECAST | ISSUE THREE | 2017

(Above, from top): The LuminTech border around a swimming pool at night; the LuminTech border around the same swimming pool.

PRODUCTS

Sika SA, a Concrete Manufacturers’ Association member, recently implemented new and improved changes to its labelling and artwork to represent the brand’s identity, while simultaneously being more practical and useful than before. When the new corporate design was

introduced in 2013, a basis for clearer lines and better reader orientation was created, which now also applies to Sika’s product packaging. The growing product range was taken into account in relation to space, as well as the changing needs

more suitable and usable for different

IMPROVED PACKAGING

user groups. These include designations,

identify which Sika product they need and

for production after use. The materials

descriptions of a product or the use of

what that product can deliver for them.

needed for some packaging are mini-

images. Sika has renewed pictures and

Except for the logo and the prominent

mised, which makes a big saving in total.

drawings on the cartridges, boxes, bags

use of company colours, the visibility of

Though Sika’s packaging will be modi-

and buckets. Now it will be easier to

the Sika products has been improved and

fied, the contents inside will not. There

identify the application field for which the

creates a unique, stand-alone product

are no changes to form, fit or function

specific product is suitable, be it profes-

label design.

of any of these products. Customers will

of the market. There are new label versions which are

sional specialists, retail trade, craftsmen

All Sika packaging is as recyclable

receive the excellent quality to which

as possible. All paper packaging is cer-

they are accustomed. All Sika solutions

The goal is to deliver a clear product

tificated, plastics are recycled for other

are designed with the customers’ suc-

message and simple orientation, which

productions and the steel and other

cess in mind in order to build long-lasting

will make it even easier for customers to

metal sheets of barrels are re-used

and mutually beneficial relationships.

E+I 4533

or DIY users.

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

GREEN CONCRETE ON SITE AfriSam has released an environmentally responsible Eco Readymix concrete that blends high-performance cement with carbonneutral mineral components to achieve excellent cementitious properties. The carbon footprint of this concrete has been reduced by 46-51%, compared with typical industry concrete, depending on the compressive strength. The Eco Readymix brands, Starmix, Foundation Mix and Retainer Mix, are developed to suit the particular construction application. “As part of our efforts to conserve the environment, AfriSam has perfected the art of producing composite cements using additives as partial replacement for cement,” says Victor Bouguenon, marketing manager at AfriSam. “Not only does this practice of recycling by-products from other industries minimise harm to our environment, but these additives enhance the performance of cement and offer advantages over ordinary Portland cement.” The additives include limestone, fly ash (a by-product of coalfired power stations) and ground granulated blast furnace slag from the steel industry. These products behave like pure cements in the presence of cement or lime. “While pure Portland cement has served the industry well for over a century, it’s now been superseded by composite cements,” says Bouguenon. “Despite their low carbon footprint, the performance of the Eco Readymix concretes is superior to concrete made from pure cements. What’s more, AfriSam is able to produce ultra-high-performance Eco Readymix concretes with compressive strengths of above 70 MPa.” He says AfriSam’s years of research and development in cement products, as well as its C-Tech technology, give the company’s products several distinct advantages over pure cements. “These include improved workability, reduced heat of hydration, reduced susceptibility to chemical attack and increased erosionresistance. They’re also less permeable, so they’re more corrosion-resistant, and they continue to gain strength over time.” (Top, from left): The performance of the Eco Readymix concretes is favourable, compared with concrete made from pure cements; AfriSam has released an environmentally responsible concrete range, Eco Readymix, that blends highperformance cement with carbon-neutral mineral components to achieve good cementitious properties.

PRECAST | ISSUE THREE | 2017

GLOBAL VIEW 20

CMA member, Terraforce, has notched up several recent successes in the UK through its licensee company, Terraforce UK. Among them are four retaining wall projects in which the Terraforce L15 block was installed with a high degree of professionalism and workmanship. One of the sites is located in the Cornwall holiday resort town of Rock, situated on the Camel Estuary opposite the fishing port of Padstow, where a 4 000-block wall was constructed. Using starter bars at the top of the vertical wall section, the

as well as a double layer of L15 blocks.

GROWING INTO THE UK

Geogrid reinforcing was placed at every

compared with other earth-retaining so-

second row of blocks of the wall’s sloped

lutions, are easy to transport and install,

section and a perforated 110ml drainpipe

and next spring we’ll plant some foliage,

was installed to drain excess water via

which will finish off the wall nicely.”

wall was built with concrete infill and nofines concrete for additional reinforcing,

two discharge points. Jon Bond, contract manager for the

Global appeal

developer, Williams Homes (Bala), says

A new residential complex, Llwyn Onn in

they intend using the blocks for future

Holywell, Wales, was the site of a second

projects. “The blocks are af fordable

installation. Here the L15’s round-face

“The fact that the blocks can be laid without mortar is what initially attracted me to the system.”

finish was chosen to retain a 4m-high building platform for some new houses. The first six courses of the 3 000-block wall were filled with concrete and the remainder of the wall was reinforced with geogrid. Then a filtered backfill layer was installed to guide any excess water into a perforated 100ml drainage pipe which runs along the full length of the wall. The third project represents a perfect showcase for a DIY retaining wall. Situated in Sheffield, this small retaining wall was built with a creative pattern of grey and red rockface L15 blocks. Martyn Symonds, who laid the blocks with the help of a family member, loved the versatility of the blocks. “I found all the information on installation easily on the Terraforce website. I then played around with different finishes, setting up a simulated test wall. The fact that the blocks can be laid without mortar is what initially attracted me to the system, and I knew I could do the work (Top): A 4m-high retaining wall in Holywell, Wales, built with 3 000 Terraforce round-face L15 blocks. (Centre): A Terraforce wall in Cornwall, England, built with a double layer of L15 blocks. (Left): An affordable retaining wall solution was provided with L15 blocks at Brill, a village an hour out of London.

PRECAST | ISSUE THREE | 2017

ognised that Terraforce blocks had the

the 200-250mm-deep foundation trench

potential to become a sought-after land-

with compacted 25-40ml aggregate and

scaping and erosion-control product for

once the first layer of blocks had been laid

the commercial and residential landscaping

perfectly level, it was surprisingly easy to

markets in England, Wales and Scotland.

finish the wall. Each block was set back

“Terraforce had many applications and

at roughly 20mm and I used pea shingle

finishes, offering a versatility unmatched

pebbles for the backfill,” says Symonds.

by other retaining wall products on the

GLOBAL VIEW

myself without too many tools. I filled

market. Besides having several colour Growing appeal

options, one can easily add a rockface

The last retaining wall is situated in the

finish by simply turning a block around,”

village of Brill, an hour away from London.

advises Craven.

(Above): A DIY wall in Sheffield built with L15 blocks.

Here Scott Morton of Landscaping &

With a licence agreement between

and ability of the block to turn a corner

Agricultural Services introduced the

Terraforce cc and Terraforce UK in place,

easily. Every site I visited was impeccably

blocks to Derek Turner of The Green

the manufacture of the L15 block was ini-

installed and each contractor was happy

Company, who needed an af fordable

tiated in 2010 by Cumbria-based Thomas

to recommend our product,” says Johns.

retaining wall solution for an exposed

Armstrong (Holdings), a well-respected

Terraforce also has several licensees

cut slope in the garden of a home he was

construction services group which was

in Canada, and in August a new licensee,

renovating. The wall reaches 2,4m at

established in 1830.

Terraforce Vancouver, was brought on

its highest point, with a double layer of

board. The blocks will be produced by

blocks installed over the first six courses.

Growing stronger

Trisar Brick & Block in Abbotsford, British

In this instance, all the blocks were

Karin Johns, marketing director of Ter-

Columbia, which suffered some devastat-

concrete-filled and backfill comprised a

raforce SA, visited the UK recently to

ing fires in recent months.

self-compacting 20mm shingle.

meet some clients in England and Wales.

And in September, across the Atlan-

The company has had a presence in

“I was very happy to see how wholeheart-

tic, the company’s international footprint

the UK for the past seven years and was

edly building contractors have embraced

was extended to Algeria, where a new

founded by Peter Craven and his business

the retaining block system. All of them

licensee, Terraforce Algeria, will be head-

partner Rebecca Lentz, when they rec-

praised the straightforward installation

quartered in Algiers.

We are there when you need support

Need help with your concrete? We offer a free advisory service for general concrete queries. Perfect concrete with us.

www.theconcreteinstitute.org.za +27 11 315 0300

ADVERTORIAL 22

ROCLA CELEBRATES

100 YEARS OF EXCELLENCE Concrete Manufacturers’ Association (CMA) member Rocla, one of SA’s leading manufacturers of precast concrete products, celebrates a century of excellence in the supply of products to the infrastructure, building and construction industries. It is part of the Infrastructure Specialist Group (ISG), which was formed in 2013 when Rocla, Technicrete and Ocon Brick were acquired by a consortium consisting of private equity firm Capitalworks, RMB Ventures, Pan African Group and senior executives within the companies. The three iconic South African brands were previously owned by Murray & Roberts, which sold them when the group chose to focus its growth aspirations on engineering, mining and construction. ISG chief executive officer Albert Weber says: “Reaching this milestone of 100 years of service and technological excellence is an achievement of which we’re all proud. It’s amazing. Rocla’s technical team offers customers solution reliability, particularly with non-standard requirements. Our technical innovation is second to none and enables us to continue building upon our rich history of excellence in a market where we’ve become the preferred choice for precast concrete manufacturing.” Some highights An example of Rocla’s innovation is the recent launch of the Rocla Thuthukisa Sanitation Initiative ( TSI). Its “Community Cast” system was established to empower local communities, entrepreneurs, contractors and SMMEs to become manufacturers and suppliers of the most innovative and highest-quality concrete toilet structures in Africa. “Thuthukisa” means “to share” and it is with this philosophy in mind that Rocla developed the “Community Cast” toilet

PRECAST | ISSUE THREE | 2017

ADVERTORIAL

unit that can be manufactured simply and be ready for use within two weeks. The resulting waste material can be recycled into practical items for everyday use. As Rocla celebrates its South African precast concrete manufacturing milestone, the importance of technical research to meet customer require-

ments has never been greater. It is critical to understand the client’s needs at the outset and this is best achieved by ensuring that the client involves all their external and internal role-players in the development of a “need definition”. A r e c en t ex ample o f inno v a tion through collaboration was the development of a precast solution using steel components for an international diamond mine based in Gauteng. Apart from designing and manufacturing precast components, the project required the development of underground installation manual and lifting equipment with handling equipment specialist Manitou. Research was conducted as far away as the Codelco Mine in Chile. While the project is still in the feasibility stage, it showcased Rocla’s ability to develop and manufacture a bespoke and unique solution to stringent client requirements. Concrete award In April 2016, Rocla’s locally manufactured concrete cabins for use at photovoltaic farms located in the Northern Cape and the Free State received the

cost-efficient, but also safe. Rocla, for

CMA Award for Excellence commendation

example, designed and manufactured

in the Innovation Category. Rocla was

many of the precast poles required by

praised by the CMA judges for its ground-

Eskom for its electrification projects

breaking advancements in the use of

across the country in the 1990s. A large

precast concrete in manufacturing these

spun concrete pole for 132kV distribution

concrete cabins, which are vandal-proof

networks and double poles for specific

and quick to assemble. The burgeoning

power transmission requirements were

South African photovoltaic farm sectors

also manufactured and designed by us.”

needed an innovative solution to house

“With public-sector infrastructure

and safeguard the electronic compo-

spend at approximately R865,4 billion

nents required at these installations and

over the next three years, we believe

Rocla rose to the occasion.

Rocla has a continuing role to play in the

The company’s technical executive,

supply and manufacture of appropriate

Gerhard Rossouw, an engineer with 40

infrastructural products in sanitation,

years’ design and application experi-

water, roads, transport developments,

ence, says: “We work with municipal and

schools and healthcare facilities,” says

consulting engineers regularly to develop

Weber. “Our 100 years of experience not

solutions for projects that are not only

only showcase our commitment to this market, but highlight the expertise that

PRECAST | ISSUE THREE | 2017

(Left): Specialised concrete poles from Rocla.

‘Team Rocla’ offers to our customers.”

(Right, from top): Operations director Roy Robins cuts Rocla’s 100th birthday cake with sales and marketing director Christo van Zyl; the Rocla Thuthukisa Sanitation Initiative.

9001:2008-certified and have the ap-

A l l R o c l a’s p r o d u c t s a r e I S O plicable SANS recognition.

PARTNER WITH PROVEN

Quality materials are nothing without quality partnerships. PPC is dedicated to helping its customers get the most from every single project through unparalled service and a holistic range of products and solutions.

Choose proven quality in every build. Choose PPC. Want to know more? Visit www.ppc.co.za

PPCisCement

ppc.cement

CMA member Aveng Infraset has invested millions of rands in a refurbishment of its core-vibration concrete pipe plant in

COMPANY NEWS

PIPE PLANT STREAMLINES PRODUCTION CAPACITY Kuils River in the Western Cape. Aveng Infraset general manager,

Stephan van Niekerk, says quality assurance has been made easier because the plant is more streamlined and now has the capacity to supply larger quantities over shorter lead times – improvements

vertical production plants at Kuils River.

which have immediate benefits for the

The second, which produces pipes from

contractor.

900-2 000mm in diameter, employs ex-

“We’ve bought new mould stock and

ternal vibrators and is used to manufac-

installed a very energy-efficient, state-

ture HDPE-lined pipes for sewer systems.

(Above, from left): A mould is lifted off a newlycast concrete pipe in Aveng Infraset’s recently installed computer-controlled production plant; freshly produced 450mm diameter pipes roll off the production line at Aveng Infraset’s Kuils River storage yard.

of-the-art, closed-steam curing system.

Most concr e te pipes in S A ar e

plant operates to ISO 9001 quality

Computer controls monitor heat build-

manufactured using roller suspension

management and all its pipes, culverts

up, ensuring constant temperatures

(RS) casting and the Kuils River plant

and manholes carry the relevant SANS

and low electricity consumption,” says

is no exception. It uses RS production

certifications.

Van Niekerk.

to produce high-quality pipes from 300-

“We’ve also upgraded the mixer

1 650mm.

W i th a f oo tpr int w hich ex tends across the SADC region, Aveng Infraset

and automated the mixing controls.

“RS production is labour-intensive

manufactures a diverse range of pre-

Moreover, all the pipe handling in our

and is very effective in providing the

cast products for the development of

core vibration plant is done by machine,

necessary compaction required for

infrastructure. These include products

which makes for a much cleaner and

thin-walled pipes,” explains Van Niekerk.

such as pipes, culverts, retaining blocks,

The Kuils River plant also manufac-

paving, roof tiles, pre-stressed poles,

safer working environment.” The core vibration plant is one of two

tures culverts in various sizes. The

masts and railway sleepers.

various retail stores in the Limpopo and Mpumalanga region. “Research showed us that when customers go to retail stores to buy cement, there often isn’t anyone on hand to assist and advise the potential customer on their purchase and ensure they choose the right product. We saw the need to have PPC ambassadors on hand to do this. Rather than using our existing sales team, we decided to give unemployed, qualified young people an opportunity to gain on-the-job experience and expose

PPC COMBATS UNEMPLOYMENT

them to the workplace,” says Corrie.

With unemployment on the rise in SA, ce-

of job-seekers surging by 433 000 people.

of technical training, advanced driving,

ment producer PPC is making a small dif-

The youth unemployment rate also rose

credit training and a mini cement tech-

ference by employing a number of young

by 1,6 percentage points to 38,6%‚ with

nology course. As part of the internship

people in learnership positions so that

58% of unemployed people aged 15-34.

programme, the interns are required to

The four graduates attended a twoweek training course which consisted

they can gain valuable work experience

PPC has developed a programme

do activations and promotions at various

to help them succeed in the workplace.

aimed at empowering and employing

retail outlets in their respective areas.

According to Marlene Corrie, PPC

young people in Limpopo and Mpumalanga

“We’re happy to make a tangible differ-

general manager for inland sales, unem-

provinces. The programme, launched

ence in the lives of these young people.

ployment in SA is at its highest level since

in April this year, has so far given four

The invaluable experience they’re receiv-

September 2003 and while the economy

young people with marketing qualifica-

ing here will really take them a long way

added 144 000 jobs during the first quar-

tions an internship opportunity to get

and they’ve also added value to our busi-

ter of 2017, this was offset by the number

involved in sales and marketing sales in

ness and the PPC brand,” says Corrie.

PRECAST | ISSUE THREE | 2017

FEATURE 26

CRB WALL FAILURE – ANOTHER TAKE The last issue of Precast featured an article on CRB wall failure and its likely causes. Based largely on the views of a geotechnical engineer, its core message was that cost-cutting and client ignorance are the essential drivers of wall failure. This month we explore other causes of the problem.

In fact, it is the general standard laid

While acknowledging that cost-cutting

patterns over the past 10 years. Today

rather than entire walls. And in most

does occur, this article, based on input

there is a high incidence of torrential

cases, these failures are covered by

from CRB wall engineer and product manu-

and localised downpours which result

insurance, as the circumstances of their

facturer Silvio Ferraris of ReMaCon – who

in f l o o ding an d th e o v er f l o w ing o f

collapse were unforeseen.

has 27 years’ experience – and well-known

stormwater systems. Some of these

international product licensor Holger Rust

storms exceed the 25-year flood mark

Agree to disagree

of Terraforce, asserts that it is not the

for which most CRB wall designs are not

It is also interesting to note that when

prime cause of wall failure. Rather, human

generally designed.

walls fail, there is seldom unanimous

error and lack of attention to detail are

down by Gauteng municipalities. Nearly all walls fail due to excessive amounts of water invading the bulk fill. However, most failures are very localised, ie small sections of wall collapse,

If walls are to cope when the 25-year

agreement among those investigating

mark is exceeded, corrective detailing

the underlying causes. This is due partly

It should be stated at the outset that

on critical areas of overflow is required.

to lack of experience in CRB wall con-

CRB walling is one of the construction

This is achieved by caulking the voids

struction, but mostly due to a failure by

industry’s many success stories, with a

below and between certain types of

investigating engineers to gather all the

proven capacity to provide innovative and

block systems in an inverted “V” so that

necessary information before reaching

eco-friendly solutions to retaining wall

water can cascade down the face of the

a conclusion.

challenges. Of the hundreds of CRB walls

wall without eroding the soil between

built every year, only a small percentage

the blocks.

the most common reasons for it.

fail, mostly within a year of completion.

Although no engineer designs a wall to fail, problems often arise right at the

Stormwater systems can, of course,

outset when the project engineer’s CRB

be designed to a 100-year flood mark,

design specification and bills of quantity

Climate change

but at huge cost. A balance must be

briefs lack essential information. Typi-

One of the factors affecting CRB wall

struck between cost and performance,

failure is the dramatic change in weather

which the 25-year mark attempts to do.

(Above): A drain channel above a CRB wall.

PRECAST | ISSUE THREE | 2017

the layout of services and their proximity above the retaining walls, and even basic essential information such as

“One of the factors affecting CRB wall failure is the dramatic change in weather patterns.”

soil parameters, surcharge loadings,

To the book

specification does not carry sufficient

wall heights and angles. Sometimes

Design engineers should refer to the

detail, either the CRB contractor or

drawings are not supplied with the

Concrete Manufacturer Association’s

the design engineer must establish the

specifications either.

NP C (CM A’s) CRB wall installa tion

parameters within which the wall should

It is virtually impossible for the sub-

manual. Crucially, it includes a typical

be designed and constructed. Even so,

contractor and his design engineer to

bill of quantities and covers most of the

the CRB design engineer is responsible

second-guess what the actual require-

requirements for constructing a CRB

for inspecting the site before and dur-

ments are if the bill of quantities lacks

wall. The CMA has also produced a film

ing wall construction. Visible evidence of

relevant details and diagrams. In fact,

(available on CD) which provides step-by-

variations in the geology, ground water

it is always the main contractor’s re-

step construction guidelines.

ingress or old buried pipes can then be

sponsibility to set out the wall before

CRB wall specifiers can also refer to

the foundations are excavated, and this

two national SABS standards: SANS

is not always done correctly.

quickly rectified.

207:2006 for the design and construc-

The bigger picture

On site, CRB contractors often find

tion of reinforced soils and fills, and SANS

This means sourcing the necessary infor-

that the project involves additional ele-

508: 2007, the specification for the

mation from the project engineers, who,

ments not dealt with in their quotations,

manufacture of retaining blocks, which

because they are focused on the whole

such as a higher wall, poor access, ad-

was published in August 2008. Alterna-

project, are usually unable to provide

ditional backfill and/or fabric reinforce-

tively, they can use an experienced CRB

it immediately. For example, they may

ment, drains and foundations requiring

wall design engineer.

not have the soil parameters required

additional sizing or reinforcing. So they

Despite inadequate bills of quanti-

to design walls to SANS 207, and they

either cut corners, building a wall in

ties and/or no drawings, it is still the

may be uncertain of the loading, heights

which the risk of failure is high, or revise

responsibility of the design engineer to

and angles, which makes the design and

their quotation, pushing the project

ensure that walls are built according to

pricing of the wall very difficult.

hopelessly over budget.

sound design principles. If the original

V I H Y

FEATURE

cally, this includes irrigation systems,

All these aspects ought to be taken

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FEATURE

into account before or during the design stage to avoid the type of situation where a service trench cuts into the geofabric after a wall has been built, rendering it useless, or an irrigation system is installed with similar consequential damage. Design flaws can also occur when the main contractor changes the original design

without consulting the CRB design engineer. This could involve raising the wall or changing a kerb position, which can alter and ultimately compromise the safety and structural integrity of the wall. To avoid the scenarios outlined above, adherence to the SANS standards as

Ground conditions

well as to the CMAâ&#x20AC;&#x2122;s Installation Manual,

Geotechnical reports are mainly in-

Code of Practice for Gravity Walls, Design

tended for piling and building foundation

required less frequently and the results

of Reinforced Walls, Design Checklist and

designs and seldom include shear box or

can be correlated with DCP tests to

various project reviews such as Hydraulic

triaxial tests. This means that if design

ensure compaction uniformity.

Applications, should be mandatory refer-

engineers rely solely on a geotechnical

Stormwater management should be

ence material. They remove the ambiguity

report, their assumptions can be off the

the overall responsibility of the profes-

as to where responsibility for design and

mark by a considerable margin; this is why

sional team, the project managers and

construction procedure lies. One of the

every site must be inspected before wall

the main contractor. It is unreasonable

important rules covers design devia-

construction commences.

to expect a sub-contractor to manage

(Above): Sub-surface drains against a cut face.

tions and how best to handle them. In

The initial geotechnical investigation

the other sub-trades such as bulk earth-

this instance, good liaison between the

must also include undisturbed shear box

works, plumbing and bricklaying, whose

project engineer and CRB design engineer

or triaxial test results as per SANS 207

site works often have a direct impact

is a prerequisite.

if the project is to include a retaining wall

on the CRB contractorâ&#x20AC;&#x2122;s progress and

element. But even thorough geotechnical

performance.

Washed away

soil tests can miss hazards which could

Most walls fail because their design

undermine the integrity of a wall, such as

On-site supervision

or structural weaknesses make the fill

a large rock, underground water or poor

Temporary stormwater protection during

prone to water saturation. Irrigation

geological soil intrusions.

the works is vital. Failure to attend to it

systems, which often leak and block with

Some design engineers insist on a

debris, can also undermine the integrity

troxler test, a nuclear device which

of a wall. It therefore makes sense for

tests compacted soil density. As this is

For example, stormwater drains are

design engineers to be involved in the

expensive and involves testing at every

often blocked. In addition, wall drains

specification of irrigation systems, as

300mm, it is generally only used when

are sometimes covered with concrete

this helps lessen the threat of leaking.

the walls are very high or when there is

when a drain channel, walkway or road is

In an ideal world, the backfill of CRB

a substantial amount of fill. DCP indicator

built next to a wall. This type of mishap

walls would contain a substantial per-

testing is used extensively by experi-

demonstrates why it is crucial for the

centage of coarse material and a low

enced contractors and their appointed

design engineer not only to design the

percentage of fines (<15% minimum

design engineers to check the indicative

wall, but to oversee its construction with

passing a 75 micron sieve). This would

degree of compaction and fill quality as

regular site visits.

reduce wall failure incidence dramatically,

work progresses. It is inexpensive and

but importing selected fill is an expensive

takes little time, but can be invaluable.

option, which is why soil found on site

will cause erosion and localised collapses, sometimes requiring a costly rebuild.

In summary, if a significant reduction in the number of CRB wall failures is to be achieved, a substantial change of atti-

is generally selected, although it may

Testing required

tude from the entire professional project

require improving.

As the compaction and classification of

team, including the CRB wall contractors,

Before engineers can design a wall,

backfill is critical, all CRB contractors

is required. It is certainly an attainable

they need accurate information on the

should initiate regular DCP indicator

goal and one that needs pursuing.

internal friction angle (Ă&#x2DC;) of the soil and

compaction tests before laying founda-

its cohesion by conducting a shear box

tions and during the construction of a

or triaxial test. SANS 207 prescribes

wall. They should also take regular photos

this test, yet in the majority of retaining

as proof that the walls were built and

wall sites, it is not done. Instead, as a

detailed according to design.

fall-back measure, design engineers use

DCP indicator tests should be man-

the geotechnical report, which includes

datory up to the full height of the fill at

results on the fines content of the soil.

1 000mm intervals. Troxler tests are

PRECAST | ISSUE THREE | 2017

APOLOGY In a previous article (July issue) on failed retaining walls, Brennan Small was referred to as Vernon Small and we extend our apologies to Brennan for this error.

TECHNICAL 30

MAINTAINING SA’S ROADS SA’s national road infrastructure, including precast concrete elements, provides a fundamental network that delivers a wide range of economic and social benefits. Adequately maintaining road infrastructure is essential to preserving and enhancing those benefits. Bakwena N1N4 toll concessionaire’s commercial manager, Liam Clarke, explains why this is more cost-effective in the medium to long term. Maintenance is relevant to all industries

damage timeously means it can be easily

that supply the country road networks

managed and cost-effectively achieved.

and includes concrete road infrastruc-

This is called routine/preventative main-

ture such as barriers, light poles, curbs,

tenance and is achieved by creating a

culverts, etc. “While it might seem over-

check-list of jobs and performing them

simplified, maintaining a road works on

regularly, without excuses.

exactly the same principles as maintain-

(Above): Road maintenance is important and includes all precast concrete structures.

“Just as home-owners should be check-

ing your home. If you don’t regularly main-

Routine maintenance

tain it, your dream home can turn into

“As the custodians of the Bakwena N1N4

ing gutters and roofs to see if the paint’s

a nightmare. Every home experiences

Platinum highway, we practise routine/

peeling, we know our roads will have taken

maintenance issues of varying degrees

preventative maintenance to keep the

a beating over the summer period, with

at some point or another,” says Clarke.

roads for which we’re responsible in a

damage caused when rain gets into the

“The reality is that these repairs need

condition that ensures the safety of all

cracks, so the winter months are ideal

to be done regularly in order to maintain

road-users. If cracks and potholes were

for carrying out repairs, before the wet

a home properly. It can be daunting to

left unrepaired, it wouldn’t be long before

season begins. The importance of main-

do everything all at once, but keeping

they became a dangerous obstacle for

tenance can’t be over-emphasised. When

everything under control by meticulously

unsuspecting motorists, resulting in

funded appropriately and managed well,

following a plan to prevent and repair

serious accidents.

maximum value is achieved,” says Clarke.

TECHINCAL 31

FIRST AID, EMERGENCY EQUIPMENT

AND PROCEDURES Employers must take all the necessary steps to ensure that persons at work receive prompt first aid treatment in case of injury or emergency. Oom Callie Calitz of OHS Consultants looks at requirements in the workplace and practical measures to ensure compliance with legislation.

that the first aider is trained in the

procedures which are necessary for

the treatment or injuries that may

result from such activities.

Companies need to provide a first aid box

• An employer must affix a prominent

notice or sign in a conspicuous place

at a workplace indicating where the

15. Four first aid dressings

first aid box is kept, as well as the

name of the person in charge of it.

(150mm x 200mm)

and supplies that meet the requirements

16. Two straight splints

• An employee with an open wound, cut,

for the kind of work and injuries that can

17. Two pairs large and two pairs medium

sore or any similar injury must report

be expected. Whenever more than five

such injury to his employer. The em-

employees are employed, the employer

18. Two CPR mouthpieces or

ployer may not permit the employee

also needs to provide a first aid box or

to continue working before the injury

disposable latex gloves similar devices

boxes at or near the workplace which

The employer must also ensure that

has been cleaned with soap and water

must be available for the treatment of

only the articles and equipment men-

or with a diluted disinfectant.

injured persons at the workplace.

tioned or other similar equipment or

• Where an employee is exposed or

medicine is kept in the first aid box/boxes.

coud be exposed to a potential hazard

of injury to the eye through contact

It is the duty of the employer to ensure that the first aid box contains suitable first aid equipment, including at least

Procedures, not pills

with a biological or chemical sub-

the following:

Where more than 10 employees are em-

stance, the employer must ensure

1. Wound cleaner/antiseptic (100ml)

ployed, the employer must ensure that

that there is an eye-wash fountain, or

2. Swabs for cleaning wounds

for every group of 50 employees at the

similar facilities, in the immediate

3. Cotton wool for padding (100g)

workplace, or in shops and offices, at

vicinity of the workplace and that

4. Sterile gauze (minimum quantity 10)

least one person is readily available dur-

employees are trained in its use.

5. Pair of forceps (for splinters)

ing working hours who is in possession of

• Where the employee is exposed or

6. Pair of scissors

a valid certificate in competency in first

could be exposed to a potential haz-

aid, issued by the SA Red Cross Society,

ard or injury to or absorption through

7. Set of safety pins

St John’s Ambulance, the SA First Aid

the skin as the result of contact with

8. Four triangular bandages

League or a person or organisation ap-

a large amount of toxic, corrosive,

9. Four roller bandages (75mm x 5mm)

proved by the chief inspector.

high-risk or similar hazardous sub-

Employers must therefore ensure

stance, the employer must ensure

11. A roll of elastic adhesive

that this employee is appointed as a first

that there is a fast-reacting deluge

aider by using the correct appointment

shower with clean water or a simi-

12. Non-allergenic adhesive strip

letter. Also note:

lar facility in the immediate vicinity of

• At a workplace where a high-risk

the workplace and that employees

13. Packet of adhesive dressing strips

substance or toxic, corrosive or

are trained in its use.

similar hazardous substances are

14.Four first aid dressings

used, handled, processed or manufac-

Safety greetings!

tured, an employer must ensure

Oom Callie

(minimum size 100mm)

10. Four roller bandages (100mm x 5mm) (25mm x 3mm) (25mm x 3mm) (minimum quantity 10 assorted sizes) (75mm x 100mm)

PRECAST | ISSUE THREE | 2017

TECHNICAL 32

Figure 3

CARBON CONCRETE: FROM RESEA German academia and the private sector are pursuing strategies backed by the German government to make concrete more sustainable and energy-efficient. Seeking alternatives to steel reinforcement forms part of this process and non-metallic glass and carbon reinforcement have been at the forefront of research for several decades. Text: Prof Dr-Ing Manfred Curbach, Dr-Ing-

Reinforced concrete is an excellent

rode, however, thus causing consider-

Frank Schladitz and Dip-Ing Egbert Müller

composite material. It is used for the

able damage, the effects of which are

construction of buildings, roads, bridges,

frequently reported in the press. To

(Published with permission from BFT

tunnels and many other structures.

prevent corrosion, the steel is enclosed

International)

Conventional structural steel can cor-

by a concrete cover several centimetres thick. Nevertheless, the lifespan of steel-

Concr ete has been in use f or over

reinforced structures is usually well

2 000 years and is today the world’s

below expectations. In addition, the large

most widely used construction material.

amounts of material used are associated

For more than 100 years, it has been

with a correspondingly high consumption

reinforced with steel (before that, iron).

of resources and energy. Basic research into alternatives to

Steel, however, is prone to corrosion and can cause major damage.

Figure 1

steel began with textile reinforcement and, over the past 10 years, has achieved very encouraging results. Moreover, the material has gradually made its way into German building practice. Carbon concrete can be used for the refurbishment and strengthening of existing structures, as well as for new construction, and there is widespread consensus in Germany that carbonreinforced concrete is the material of the future. (Above, left): Comparing reinforced concrete (rear) and carbon concrete (front). (Image: C³/Jörg Singer)

Figure 5

(Left): Refurbishment of a former railway bridge in Naila – execution: Laumer Bautechnik GmbH. (Image: C³/Jörg Singer); refurbishment of a former railway bridge in Naila – execution: Laumer Bautechnik GmbH. (Image: C³/Jörg Singer);

PRECAST | ISSUE THREE | 2017

TECHNICAL 33

Figure 4

“Carbon Concrete Composite – C³” Figure 6

is a major research project initiated in 2014. It is currently the world’s larg-

ARCH TO APPLICATION

est research project in construction

Material performance

additional functions such as integrated

third comprising research institutions)

As many as 50 000 carbon filaments –

heating, measuring, data transmission

are collaborating in the development and

each of which is thinner than a human hair

and storage. Figure 1 compares steel-re-

nationwide introduction of carbon con-

– are combined into carbon yarns. Using

inforced concrete with carbon concrete,

crete construction. The Federal Ministry

dif ferent manufacturing processes,

while Figure 2 illustrates the production

of Education and Research (Bundesmin-

these are used to produce grid or bar

of a carbon concrete beam.

isterium für Bildung und Forschung –

engineering in which over 140 partners (two-thirds of which are enterprises and associations, with the remaining one-

BMBF) is funding the project with around

reinforcements. Carbon reinforcement is around four times lighter than steel rein-

Development

€45 million; the partners’ equity capital

forcement (with a density of 1,8g/cm³,

Initial tests with alternative types of

amounts to approximately €20 million.

rather than 7,8g/cm³) and its structural

concrete reinforcement were conducted

This large project has been divided into

capacity is six times higher (a tensile

as early as the 1980s and were expanded

over 50 research partnerships. Since

strength of 3 000N/mm², rather than

during the 1990s [1, 2]. Between 1999

2015, ground-breaking research work

500N/mm²). As a result, the performance

on reinforcement, coatings, binders,

of carbon is roughly 24 times better than

concretes, structures, design, mate-

that of standard steel reinforcement.

rial testing and initial multi-functional

Carbon’s low weight makes it less

structural elements has been conducted

expensive to transport and easier to

in four extensive basic projects. At

install. Carbon-reinforced concrete

the beginning of 2016, projects were

covers the full gamut of available mixes,

launched to lower the barriers to market

from standard ordinary concretes to high-

entry. The areas addressed here include Figure 2

performance fine concretes and special ultra-high-performance concretes. The

not only manufacturing and processing operations, standards and approvals, or

concrete mix design depends on the

and 2011, two collaborative research

occupational safety, but also demolition,

intended use, namely strengthening, new

centres of the German Research Founda-

deconstruction and recycling.

construction, precast elements or in-situ

tion (Deutsche Forschungsgemeinschaft

New projects were launched at the

concrete, and on the production process,

– DFG), based in Aachen and Dresden,

beginning of 2017. In 2018 and 2019, the

such as pouring or laminating.

were the key drivers of basic research

focus will be on projects addressing spe-

As carbon does not corrode, it only

in the field of non-metallic types of re-

requires a concrete cover of a few milli-

inforcement in that country. The prior-

metres, whether in new construction, re-

ity was on developing textile-reinforced

furbishment or strengthening. In addition

concrete using AR glass fibres. It was

to its structural function, the electrical

only in the final phase of this research

conductivity and electrical resistance of

that the focus gradually shifted to carbon

carbon reinforcement enable it to take on

reinforcement.

PRECAST | ISSUE THREE | 2017

(Top, from left): Comparing a reinforced concrete beam (left) and carbon concrete beam (right) – production: Betonwerk Oschatz GmbH. (Image: Opterra); urban complex “NeuerMarkt” in Neumarkt i d OPf – execution: Max Bögl Fertigteilwerke GmbH & Co KG. (Image: Firmengruppe Max Bögl/Reinhard Mederer); carbon concrete wall element offering storage space for storage media, developed by the Autartec joint project. (Image: Ulrich van Stipriaan)

of carbon textile in a strengthening

In addition to the areas mentioned above,

layer no mor e than 15mm thick . A

individual companies are conducting their

barrel roof built in Zwickau in 1903 and

own application-orientated research

measuring approximately 7m × 16m was

work. The objective is to bring initial

strengthened in 2008. In total, 800m² of

products into the market quickly. Further

carbon textile was applied on the 8cm-

information is provided on the BMBF [2]

thick reinforced concrete structure in

and C³ consortium [4] websites.

three layers at an overall thickness of

Carbon concrete is also being re-

no more than 15-25mm.

searched on a large scale in numerous

A combined residential and of fice

other small and large research projects,

building was strengthened in 2009. The

such as the Autartec growth core. Fig-

ceilings of the newly built structure

ures 3 and 4 show some examples of pre-

exhibited insufficient structural capacity

cast where the saving on concrete usage

and major deflections of up to 15cm.

concrete exceeds 50%. The transfer of

As a strengthening measure, a total of

knowledge to the marketplace is being

3 000m² of carbon textile was applied on

made on a regular basis at numerous

the bottom side in three to four layers.

symposiums, during educational events

A 20 000-tonne sugar silo (with a

hosted by chambers and associations, as

height of 45m and a diameter of 30m)

well as through special training courses.

built in 1963 was str engthened in 2012. A cylindrical reinforced concrete

Live projects

silo required extensive crack repair and

Numerous real-life projects around the

14 000m² of carbon textile was applied

world involve the use of carbon concrete.

in four layers. The strengthening layer

In Canada and Japan, bridges with carbon

had an overall thickness of 20mm.

reinforcement were built as early as the

Fire damage in an 80 000-tonne sugar

1990s [5]. Numerous bridge projects in

silo was repaired using the same method

the USA are illustrated in [6]. The infor-

in 2015. Another project involved the

mation provided in the following section

refurbishment of a more than 100-year-

is limited to selected German projects

old arched railway bridge in Naila using

using carbon reinforcement. Numerous

carbon concrete in 2016. Large cracks

renowned enterprises, including the likes

in the 19m-wide arches were spanned

of Hering Bau GmbH, Implenia SE, Laumer

using 800m² of carbon reinforcement

Bautechnik GmbH, Max Bögl Bauservice

(see Figure 5).

GmbH und Co KG, Torkret GmbH and Betonwerk Oschatz GmbH, have already

New construction

begun using carbon concrete.

In Germany, new structures with textile

References / Literature 1. S c h e e r e r, S, S c h l a di t z, F, Curbach, M: “Textile-reinforced Concrete – From the Idea to a High-performance Material”. In: Brameshuber, W (Hrsg): Proceedings of the FERRO-11 and 3rd ICTRC in Aachen. Bag neux, France: Rilem Publica tions SAR, 2015, pp15-33. 2. Taerwe, L: Non-Metallic (FRP) Reinforcement for Concrete Structures: Proceedings of the Second International Rilem Sym posium, Taylor & Francis, 1995. 3. Bundesministerium für Bildung und Forschung (BMBF): Zwan zig20 – Partnerschaft für Inno v a ti on, w w w.un t er n ehm en region.de/de/6829.php 4. C³-Konsortium: www.bauen neu-denken.de 5. Rizalla, SH, Tadros G: “FRP for Pre-stressing of Concrete Brid ges in Canada”. ACI Special Publication, 215, pp75-90, 2003. 6. Ushima, K, Enomoto, T, Koso N, Yamamoto, Y: “Field Deploy ment of Carbon Fibre reinforced Polymer in Bridge Applications”. PCI Journal 61, 5, 2016, S29-36.

reinforcement have mainly been built

concrete bridges in Oschatz, Kempten

Strengthening projects

using AR fibre-glass as reinforcement,

and Albstadt-Lautlingen, as well as fa-

A hypar roof built in Schweinfurt in

which has been researched for a signifi-

çade panels in the Leipzig Zoo and the

the 1960s was strengthened in 2006.

cantly longer period than carbon. Exam-

“NeuerMarkt” urban complex in the city

This project involved the use of 450m²

ples include the three textile-reinforced

of Neumarkt. Carbon reinforcement has to date only been used in a small number of demonstration projects. However, they give impressive proof of the inherent potential of the material. Examples include two pavilions with design thicknesses of 4cm and 6cm respectively, a balcony floor slab with a thickness of only 7cm instead of the 20-25cm usually required for reinforced concrete, a floating pontoon with external dimensions of 3m x 3m x 3m and a wall thickness of 4cm, as well as a heated exterior sandwich wall element. Germany’s

Figure 7 (Above): Pouring a carbon concrete beam at the Oschatz concrete plant. (Image: Opterra)

PRECAST | ISSUE THREE | 2017

first carbon concrete bridge was built in 2016. Figure 7 shows the bridge, which is 15m long but only weighs 14 tonnes.

TECHNICAL

cific applications, products and services.

PROJECTS 36

In a break with traditional building methodology, Big Ben Construction has opted for precast rather than in-situ concrete beams as part of the materials mix being used to build 126 houses at Clara Anna Fontein, an upmarket housing estate in Durbanville, Cape Town, which is being brought to the market by the Rabie Property Group.

PRECAST BEAMS FOR PRESTIGIOUS HOUSING DEVELOPMENT we dovetail our deliveries with Big Ben’s construction schedule. This ‘just-in-time’ approach works well for both parties. It means good stockturns from our side and offers Big Ben a simpler, more efficient, quality-consistent construction technique.

Phase 1, which began in January 2017

Getting involved

and is due for completion in April 2018,

“Clara Anna Fontein is a prime example of

comprises 57 houses of which 21 are

how the TopFloor total-solution approach

double-storey units. Supplied by CMA

works. This entails our getting involved

member TopFloor, the beams are be-

in the planning stages to assist with

ing deployed in cantilevered designs to

more efficient and cost-effective building

dispense with corner support columns.

practice, which in this instance not only

In addition, TopFloor is

resulted in the use of hollow-core slabs,

supplying pre-

but in the beams as well.”

stressed hollow-core slabs for the

TopFloor has also developed a steel

upper-floor construction of the double-

plate connection to facilitate quick and

storey units. According to Richard Chatrer, a Big

easy interlocking of beams. Developed

Ben contracts manager, the beams could

by TopFloor engineer Howard Ruiters, it

have been constructed in-situ, but this

replaces the sleeve and rebar method

process would have taken weeks, rather

which was used in the initial stages of

than the hours it took to offload and place

the development. Demand for houses at Clara Anna

TopFloor’s beams into position. but this is the first time we’ve opted for

Fontein has been high, with the majority

Consistent quality

precast beams in a housing development

of units in Phase 1 sold. The building of

“Speed was a major consideration in our

on this scale. Our use of precast beams

Phase 2 will commence in late 2017, with

pre-construction planning and so were the

hasn’t gone unnoticed: other independent

completion of units from May 2018 to

consistent-quality finishes that come with

builders at Clara Anna Fontein have ob-

early 2019.

precasting. Moreover, the time-wasting

served what we’re doing and are now also

clutter associated with formwork, shut-

using TopFloor’s beams in the construction

tering and ready-mix trucks, not to men-

of their houses,” says Chatrer.

tion in-situ’s long curing times, fall away.

TopFloor MD Wessel Prinsloo says

Once the beams are installed, we simply

that because all the houses are built to

have to do the stitching and then resume

individual designs, the beams and slabs

building the following day.

are being custom-made. “Careful plan-

“We’ve been using TopFloor pre-

ning and co-ordination between ourselves

stressed hollow-core slabs for many years,

and Big Ben are required to ensure that

(Top): A row of house under construction at Clara Anna Fontein. (Above centre, from top): One of the double-storey units at Clara Anna Fontein in which cantilevered beams are used for first-floor hollow-core slab support and roof eave support; a window on a double-storey unit demonstrates how the use of precast beams precludes the need for supporting columns; TopFloor hollow-core slabs are supported by load-bearing walls and precast concrete beams.

PRECAST | ISSUE THREE | 2017

PROJECTS 37

Concrete Manufacturers’ Association (CMA) member Technicrete recently completed two large road contracts in the Limpopo area which underscore the suitability of concrete pavers in rural areas due to their durability and labour-intensive construction.

LIMPOPO ROAD PAVEMENT UPGRADES In mid-2015, Limpopo’s Public Works &

private commercial developments,” says

kerbs) and was initiated by the Limpopo

Infrastructure Department announced

Hendrik Steenkamp, sales consultant for

Department of Public Works, Roads &

that R1,2 billion had been earmarked for

Technicrete ISG in Polokwane.

Infrastructure.

road refurbishment and maintenance to

“Our precast concrete kerbs are an

PGN civils director Tintswalo Mothupa

be rolled out over the next three years.

ideal edge restraint in the construction

says: “The upgrade of the gravel access

Included in this roll-out was maintenance

of road, kerb and gutter systems. We can

road formed part of a general upgrading

to a section of the Moletjie Road Project

also now offer our Figure C900 mount-

project for the Go’on’o Village area. The

in Polokwane, which was to be upgraded

able kerb, which can be utilised in traffic

upgrade of the road makes vehicle traffic

from gravel to paving. Technicrete’s

calming measures. We were pleased to

easier and the sidewalks make it a safer

Bond Brick and kerbs were selected for

have joined forces on this R2 million pro-

environment for pedestrians.

this project.

ject with MacP Construction.

Mak ap ani Modip a, CE O o f MacP

“Where heavy traffic is experienced,

Construction, says: “There was no es-

our Bond Brick paving blocks are perfect

“Additionally, it was important that

tablished pavement on this section of

because of their well-established reputa-

members from the local community

Moletjie Road – it was a gravel walkway

tion for longevity and quality, while still

received skills training so that they

that needed to be upgraded to a paved

offering a really good finish aestheti-

could participate in the application of

surface. Included along this stretch of

cally. We aim to ensure that all stock is

the paving and kerbs, as well as other

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

supplied as per client requirements and

associated construction activities. The

commodated in the construction.

this was the case on the Moletjie Road

ability to upskill and become employable

Project,” says Steenkamp.

is critical in these outlying rural areas,”

Local upliftment

adds Mothupa.

Project plan “We chose the Technicrete Bond Brick

Gon’o’o Village

and kerb products due to their durability.

Another project situated in the north-

grey class 40 DZZs, 5 000 80mm

This was a key factor for the bus stop

east of Limpopo Province, in the heart

terracotta DZZs and 1 500 figure 8c

development, due to the weight and regu-

of the bushveld, was also undertaken in

mountable kerbs. “Every infrastructure

larity of the bus traffic. The good pricing

the rural town of Giyani. While the area is

project is important, particularly when

and reputation for reliable servicing made

comprised mainly of rural villages, infra-

local community members can receive

them a natural choice for the Moletjie

structural upgrades are required for the

skills training to earn or supplement

Road project,” adds Modipa.

continued upliftment of local communities

their income as they did at Go’on’o Vil-

in terms of residential and transporta-

lage. We take our role in such contracts

tion facilities and skills development.

very seriously. It’s always a pleasure for

“The project consisted of a combination of 50mm Bond Bricks together with

Technicrete supplied 36 000 80mm

Fig 8B Kerbs, 60mm and 80mm Double

CMA member Technicrete was recent-

Technicrete to be part of these kinds of

Zig-Zag Grey pavers and Fig 3’s Kerbs.

ly contracted to supply the paving and

projects,” says Mishack Mdhluli, sales

The Bond Brick is a traditional paver that

kerbs required to upgrade Phase Two of

representative for Technicrete ISG in

offers economy and durability and is very

a 5,10km gravel access road, the D3892,

Polokwane.

well suited to commercial and domestic

by Tzaneen-based PGN Civils at Go’on’o

surfaces. It’s been a preferred choice

Village. The entire upgrading project is

not only of local municipalities, but also of

valued at R8 million (for the paving and

PRECAST | ISSUE THREE | 2017

(Left and top right): Moletjie Road upgrades. (Above): The beautifully constructed road in Go’on’o Village.

PROJECTS

pile, which extended ±500mm above the waterline. Once in position, they were filled with concrete and anchored to the existing berth with steel braces. Rubber-lined berthing fenders were bolted onto the pile caps once they had been firmly secured to the existing berth. Thereafter, Bedrock’s concrete pier pan-

els were mounted between the existing berth and the pile caps, thus extending

MOZAMBIQUE BULK TERMINAL

BERTH EXPANSION

the width of berth by an additional 6,7m. Bedrock general manager David Kitching says that without the use of precast concrete, the berth-widening process would have been far more complicated. “It would have involved considerably

Durban-based precast concrete pro-

cast at Bedrock’s yard in Westmead to

more materials and man-hours, not to

ducer, Bedrock Group, has exported 16

a strength of 40MPa. The 6,7m x 3,9m x

mention the added complexity of working

precast concrete units for a brownfields

280mm panels weigh 19 tonnes each and

in an elevated position above the water-

expansion of an existing deepwater

were cast at South African Shipyards’

line. Precast concrete made the entire

berth at the bulk magnetite/coal ter-

barge dock to a strength of 40MPa.

operation much quicker, simpler and more

minal handling facility at Matola Bulk

Because of their exceptional weight,

Terminals, Maputo’s bulk terminal port

neither the pile caps nor the panels were

in Mozambique.

suited to road transport and were there-

The precast units comprised eight hol-

fore loaded onto barges and shipped to

low pile caps and eight pier panels. Weigh-

Matola Port by sea. The pile caps were

ing 34 tonnes apiece, the pile caps were

lowered by dockside crane onto each

economical,” says Kitching.

(Above, from left): One of Bedrock’s concrete pier panels is lowered onto a pile cap and existing berth. The two other pile caps await installation; one of the rubber-lined berthing fenders after attachment to a pile cap.

CONCRETE ROOF TILES FOR HOUSING ESTATE Flat-profile concrete roof tiles are being used by property developer Anton Mulder Construction for the roofing component of Turnberry Village, an exclusive 250 housing project construction situated just of f the R300 on the Haasendal Estate in Cape Town. Manufactured by Concrete Manufacturers’ Association member Monier/Coverland, the flatprofile Elite tiles are being installed by roofing specialists Elegant Roofing and Rome Roofing. According to Willie de Witt, Anton Mulder Construction’s project manager at Turnberry Village, the Elete tile is popular in upmar ke t de v elopments because of its aesthetic appeal and ease of use. “All the roofs at Turnberry are, of course, insulated to meet the R values of

(Above): Monier/Coverland’s Elete roof tile is put to good effect at Turnberry Village.

range from 130-188m².

visible and accessible from the estate.

current legislation and we find they also

A second precast concrete element,

Construction of a shopping mall on

work well with clip-lock metal roofing,

namely grey precast concrete cob-

Haasendal E st a te, f ea tur ing many

which we’re using on the garages and

blestones, were laid on all the internal

national brands, will begin soon.

over some of the patios,” he says.

roads of the estate, matching the Elete

Monier/Coverland has been manufac-

charcoal roof tiles and overall colour

turing concrete roof tiles for the past

scheme of the houses perfectly.

65 years and is part of the BMI group,

Begun in 2015 and due for completion in 2018, the Turnberry houses are being built using 20 different plans in single-

Turnberry Village is situated next

and double-storey configurations which

to the Kuilsriver golf course, which is

the largest manufacturer of flat and pitched roofing systems in Europe.

PRECAST | ISSUE THREE | 2017

PROJECTS 39

CONCRETE BLOCK PAVERS ASSIST WITH PRESERVATION OF HERITAGE SITE The Western Cape fishing village of Kassiesbaai is a national monument and tourist destination situated cheek-by-jowl with Arniston, a popular holiday resort renowned for its whitewashed seaside cottages and azure seas.

tion, and entailed paving roads and walk-

With antecedents dating back to the

cobbles, which were also used to create

first half of the 19th century, Kassies-

1 082m² of open stormwater drainage

baai is one of the few remaining historic

channels running adjacent to the roads.

members were created as a result of

fishing villages in SA. Part of its pres-

The main contractor on Phase 2 was

these projects. They formed part of a

ervation has entailed the paving of its

Hyman Masterfence. Completed at the

44-member team who lived within the

gravel roads and walkways with concrete

end of August 2017, it covered a simi-

Cape Agulhas Municipal area and did all

block pavers supplied by CMA member

lar distance to Phase 1 and an area of

the installation work. The project was

CEL Paving, in a project first initiated by

6 100m². According to the project engi-

very labour-intensive and all the layer

Heritage Western Cape in 2008.

neer and manager on both phases, Theo

work –including the box-cutting and, of

Funding for the project was approved

Portwig of WEC-Consult, the Euro cobble

course, the laying of the pavers – was

by the Department of Rural Development

was recommended due to its accurate

done by hand.

& Land Reform in 2013 and the first

multi-tone colouring.

ways spanning 6 400m² over a length of 1 180m using CEL’s unhammered exposed-aggregate Vintage pavers. The paving blocks came with a marble chip finish and light tan colouring, which was specifically selected to match the naturally occurring limestone-bearing sandstone of the area. The Vintage pavers were edged with CEL’s Pavatile Euro

phase of the two-phase project was

“Pavers harmonise well with each other, as well as blending in with the windblown dune sand.”

“The roads were laid with 150mm G5 sub-base material compacted to 97% of

completed at the end of March 2015.

Nature’s harmony

MOD AASHTO max density and the high

Both phases were executed on behalf of

“CEL’s Euro cobble and Vintage pavers

calcrete content of the local grounds

the Cape Agulhas Municipality.

harmonise well with each other, as well as

conditions provided a good in-situ road

blending in with the windblown dune sand

bed,” says Portwig.

Joint venture

and randomly exposed limestone-bearing

Phase 1 was a joint venture between

sandstone ridges and rocks.

Cape Agulhas Civils and Annev Construc-

PRECAST | ISSUE THREE | 2017

“New jobs for 28 local community

(Above, left): A section of road being paved at the fishing village of Kassiesbaai. (Above): Newly paved roads at Kassiesbaai.

PROJECTS 40

Several large-scale infrastructural projects are underway, with precast products being supplied by Concrete Manufacturers’ Association member Rocla, a company with a 100-yearold history of supplying products that have helped build the nation.

PRECAST CONCRETE INFRASTRUCTURE D road consisting of new culverts on the

River crossing

new road sections and on the extensions

Part of the Polokwane Eastern Ring Road

of existing culverts, as well as replacing

project includes a bridge structure under

In the first project, six new bridges and

existing culverts with insufficient hy-

the north-south-bound B0260A, with

four new major structures (overpasses)

draulic capacity. The minor culverts are

Ramp C serving to channel the river un-

will be constructed along Phase Two

pre-fabricated culverts constructed on

derneath and precast SATS culverts will

of the Polokwane Eastern Ring Road

in-situ cast floor slabs. The sizes range

be installed due to the load subjected by

development. This will align the N1-27

from 900 x 600 Box Culverts (BC) to

the amount of fill that will be constructed

towards the south of Polokwane in order

1 800 x 600 BC portal culverts and

over the culvert. An estimated 180 No

to ensure a more streamlined traffic flow

2 500 x 1 500 SAR culverts.

0-5m SATS culverts will be installed on

on this very congested freeway. The N1

“Diameter pipe culverts of 900mm

Ramp C and 480 No 5-10m SATS culverts

through Polokwane is the main route to

will also be constructed and 900mm-

will be installed under the north- and

Beit Bridge for entry into Zimbabwe and

diameter median pipes (approximately

south-bound carriageways.

carries an enormous amount of consumer

930m long) are to be constructed to

“We were faced with an excavation

and freight traffic daily.

address median drainage in cuttings.

challenge on the R4540 Roodepoort

Rocla was contracted to supply the

We’ve worked with Rocla before on a

bridge, as blasting demolitions due to the

culverts and interlocking joint pipes for

variety of projects, so we know the

tight location of the structure weren’t

this project due to its expertise in the

quality of its culverts and associated

possible. We therefore had to excavate

local manufacture and supply of these

products – it’s very good. We required a

the road for 2,4m below ground level in

specified products. “This project com-

broad spectrum of culvert sizes to cover

order for our work to progress. This is a

menced in December 2015 and is sched-

vastly differing lengths, as well as the

very large project that’s been badly needed

uled to be completed at the end of 2018.

appropriate interlocking joint pipes, all of

in the Polokwane area for some time, and

The N1-27 will become a four-lane undi-

which appear on the Rocla product list,

we were pleased to have been selected by

vided dual carriageway of 10,5-11,5km

but had to be supplied to our engineer’s

Basil Read to work with it,” says Lubbe.

and a four-lane divided dual carriageway

specifications and delivered to site as

of 11,5-14,9km, which will give preference

required,” says Lubbe.

“The challenges faced so far on this project included accommodating the daily

to traffic flow on the N1-27 Ring Road,”

“The competency of the Rocla techni-

heavy traffic loads while work was in

says Abri Lubbe, site agent for Basil

cians in assessing, assisting and advising

progress, and this was done with care-

Read, the primary contractor.

us in the correct technology and product

ful planning and re-routing in order to

selection was extremely helpful to have

minimise the disruption to traffic flow. I

Large volumes

on this enormous project. The Rocla pric-

believe that we at Rocla have such vast

“In addition, approximately 80 minor cul-

ing was very competitive and is one of

experience in major municipal infrastruc-

verts are to be constructed on this ring

the key factors that stood in its favour.”

ture developments and upgrades that we

PRECAST | ISSUE THREE | 2017

(Left): Installation of culverts in progress.

and two legs which are placed on a concrete base. This base can be cast in-situ or prefabricated.

road’ for the duration of the project and excavation of 30 000m³ of soil. The

Popular poles

removal of old and collapsed pipes had to

At the same time, Rocla is undertaking

be conducted with cutting torches due

many projects to supply concrete poles.

to a bridge collapse on a section of the

These are being used in applications

D528 road.”

across a wide variety of sectors which include electricity, electrical, telecommu-

Challenging work

nications, security monitoring, stadium

“Rocla’s SAR culverts were chosen due

and street lighting, park and public place

to their quality, longevity and capacity.

lighting and fibre-optic poles.

Ninety-three units of 2 000 x 2 000 SAR

The company has a long and estab-

culverts (5-10m fill height) were supplied

lished reputation in the manufacture

for the flood-damaged bridge element

of concrete poles in SA, Namibia and

of the project. Because Rocla’s SAR

Botswana, of which its spun poles are

culverts were custom-designed to our

manufactured from durable, partially pre-

requirements, they were loaded onto tip-

stressed or reinforced concrete. Rocla

SPEEDS UP DELIVERY

per trucks and then offloaded individually

cast and rectangular poles are made in

in order to ensure that no damage was

steel moulds from concrete with a mix

caused to each culvert,” explains Chuene.

designed to achieve the strength and

Robert Hill, sales representative for

durability to meet a wide variety of dif-

Rocla in Limpopo, says the project threw

ferent customers’ requirements.

up some challenges, from inclement

Concrete poles have become the

weather to traffic constantly trying to

benchmark in long-life, zero-maintenance

were able to offer valuable assistance

use the damaged and collapsed sections

street lighting poles. They are vandal-

to Basil Read on this Polokwane Eastern

of the road, but nothing that could not be

proof and available in a range of heights,

Ring Road project and, coupled with our

overcome by the contractors and Rocla’s

load capabilities and fitting require-

technical and product expertise, it’s a

technical support team.

ments. With increased installation of

The SAR culvert is best suited for

fibre-optics, the Rocla poles are also

use in stormwater applications with

being widely used to build infrastructure

high loadings, but can be applied in any

and replace the previously used wooden

Road rehabilitation

application where excessive fills must be

poles due to the advantages of concrete.

Another project aimed at addressing re-

accommodated. Units consist of a deck

win-win partnership,” says Sarel Pretorius, Rocla sales representative.

curring potholes from flooding in Limpopo

Electricity solution

Province has also been undertaken. Over

In line with SA’s commitment to elec-

the past few years, damage from the con-

tricity for all, Rocla has also developed

stant weight of heavy articulated trucks

cast concrete poles for the electrical

made the rehabilitation of the D528 road

distribution industry, while the advanced

in George’s Valley near Tzaneen essential.

tall spun pole is used on transmission

In addition to the quickly deteriorat-

lines like those found in Richards Bay

ing road surface and bridge, a sinkhole

and similar facilities. T he concrete

had developed under the road’s surface,

poles offer benefits that include vandal-

threatening a complete collapse of this

resistance, standardised fittings, quick

section of the D528. Rocla’s SAR cul-

installation and a maintenance-free long

verts were selected for the rehabilitation

life, all factors which the old, traditional

of the bridge section. Polokwane-based

wooden poles lack.

Batlagae Investments was awarded the

Veld fires in outlying farming and

contract to commence the rehabilitation

other facilities cause seasonal damage

of the D528 road.

and, at times, complete destruction of

Thapelo Chuene, project manager at

wooden poles housing reticulation sys-

Batlagae Investments, says: “This 30km

tems for electricity supplies of 11kV and

section of the road became known as the

22kV of power, making regular replace-

‘deathtrap’ because of the disintegrat-

ment uneconomical. The installation and related maintenance costs of concrete

ing bridge and road surface. Many challenges faced us on this project, such as the accommodation of fibre-optic lines, bad weather, the development of a ‘safe

PRECAST | ISSUE THREE | 2017

(Above, from top): Culverts ready for installation along Phase Two of the Polokwane Eastern Ring Road development; the D528 road rehabilitation project underway.

poles circumvent this type of damage and offer a far more affordable and durable option.

PROJECTS

(Far left): Concrete poles are replacing wooden and steel poles in a number of applications.

PROJECTS 42

(Left): The Jura cobble walkway inside No. 5 Silo. (Photo by Lauren Rautenbach) (Above); Inlaid with Revelstone’s York cobble, this is one of several paved octagons outside the Zeitz Museum of Contemporary Art Africa. (Photo by Lauren Rautenbach) (Below left); Revelstone’s Jura paver was used extensively on the eighth- and 12th-floor sundecks. (Photo by David Beer)

Designed by Van Der Merwe Miszewski Architects and Makeka Design Lab, the buildings achieve a high degree of sustainability with no compromise in utility, comfort or aesthetics. Built as three towers separated by lift shafts and stairs, No. 3 Silo’s architecture echoes the adjacent Grain Silos redevelopment which encompasses the Silo Hotel and the Zeitz Museum of Contemporary Art Africa, which opened to the public in September.

SILO DEVELOPMENTS AT V&A WATERFRONT Precast concrete has been used in the construction of three new buildings at Cape Town’s V&A Waterfront, No. 3 Silo (apartment building), No. 4 Silo (gym and retail space) and No. 5 Silo (office space). These buildings front onto a circular plaza, which is paved with precast concrete cobbles and flagstone pavers, most of which were supplied by CMA member, Revelstone.

No. 3 Silo features two upper-floor

The channels were specified by the ar-

And, in a break with conventional pav-

swimming pools. One forms part of an

chitects to cover electrical cabling and

ing practice, Revelstone’s external Jura

eighth-floor sundeck and the other holds

water piping which were attached to the

cobble paver was used at No. 5 Silo for

centre stage in the entertainment area

exterior pool walls. Although hidden, the

both its external paving requirements

on the 12th-floor roof deck of the pent-

pipes and cabling are easily accessible

and its internal public area flooring.

house. Both pools command spectacular

without digging or disruption to the cop-

views over the Waterfront, the City Bowl

ing or surrounding paving.

Lloyd Rubidge, a partner of Van Der Merwe Miszewski Architects, says that

and Table Mountain, and both are fringed

In addition, Revelstone’s Jura straight-

the intention was to create an ambience

with purpose-made charcoal-coloured

edge paver was used extensively at No.

of ‘external’ street space inside the

coping, which was post acid-etched to

3 Silo. It covers a path leading from the

building’s main atrium. This street-space

provide a non-slip surface.

inside of the building to the sundeck on the

design was accentuated by edging the

Revelstone designed the coping with

eighth floor and the outer ledges which

tiles with high-grade non-slip porcelain

120mm x 100mm lips which extend be-

fringe the eighth- and 12th-floor decks.

tiles and by cladding some of the walls

yond and down the side of the exterior

A smaller version of the Jura paver was

with exposed precast concrete masonry.

pool walls and create 50mm x 50mm

also used as coping for a lily pond on the

channels between the lips and the walls.

eighth floor.

“Precast elements have formed a crucial element of the overall materials pool

The plaza was paved with a combi-

for these buildings and assisted us in ex-

nation of Revelstone’s York cobble and

tending the Waterfront’s semi-industrial

Devon cobble. The former has a rounded

aesthetic,” adds Rubidge. “Moreover, we

stone-textured finish which resembles

wanted to avoid monotony, which is why

traditional European granite cobble-

we varied our choice of materials in terms

stones, while the latter is ideally suited

of design, size and colour. However, in the

to heavy vehicle traffic. A larger version

main, we opted for muted colours which

of the Jura straight-edge paver with

wouldn’t detract from other plaza at-

a rough textured surface was used to

tractions such as boutique shops, plant

create a path across a centre-piece

life and open-air cafés, restaurants and

flowerbed feature in the plaza.

public spaces.”

PRECAST | ISSUE THREE | 2017

ADVERTORIAL 43

MONEY FOR NOTHING

be further removed from the truth if

Comparing Eirich mixing technology with

mixer is capable of a minimum batch

capital expenditure.

other mixers – pan mixers, paddle mix-

cycle time of two minutes.

ers, stationary pan mixers, twin shaft

• This equates to 30 batches per hour

making machines, but are also suitable

drum mixers and spiral drum mixers

• R32,20 X 30 = R966 per hour

for any concrete application such as wet

(ready mix) – produces cost-savings

Most concrete factories work a

and profit margins for users of this

nine-hour day.

machinery.

• 9 x 30 x R32,20 = R8 694 per

We believe Eirich mixers should be

standard equipment in any concrete ap-

Eirich mixers are not only for block-

cast mixing, dry cast, semi-dry cast, blending applications, etc. Eirich has been the pioneer in material processing ever since opening its

This amounts to saving as much as

doors in Germany in 1863.

the following monthly:

reduced rejects are the order of the day.

• R8 694 x 21 working days = R182 574

Eirich has an extensive range of

in the production line and not only the

day on cement

plication where quality, time, cost and

The saving continues:

mixers (from 5-14 000lt) to suit any

one takes all aspects into consideration

Eirich intensive mixers

An Eirich plant will manufacture highvalue, high-quality concrete, heavily pigmented products. Featuring the Eirich Intensive Mixer, the

concrete need – from lab tests to big

save energy due to ef-

installed plant cost can be re-

production demands.

ficiency time which is

couped in cement savings alone

What makes Eirich mixing technology superior to the rest? The example below illustrates the

reduced drastically. The fact that a person can save on cement

in less than five years. Sav ings in power, water, pigments and maintenance will

kind of savings that can be achieved for

means that one utilises

more than compensate

companies using Eirich mixers:

less water. Theory states:

for any original capital

• 2 400kg of fresh concrete = 1m3

more water, more cement

• Assuming we use 12% cement per

and vice versa. Less cement

1m3 of fresh concrete = 288kg

thus equals less water. Hence

By using an Eirich mixer you save as

expenditure. So how cheap is cheap, actually? Oper-

the savings using Eirich mixers

ating cost advantages

much as 10% cement per mix.

compared with the traditional

do no t end when the

• 2 400kg of fresh concrete = 1m3

pan mixer, planetary mixer or twin shaft

purchase price is recovered.

• 12% cement per 1m3 of fresh

mixer (to name but a few) are as follows:

After that, it is money for nothing.

1. Cement saving of approximately

concrete = 288kg

• 10% of 288 kg = 28kg The cost-saving amounts to: • 28kg of cement at R1,15 for 42,5R

cement = R32,20 per mix An Eirich RV19 intensive 1 500-litre

PRECAST | ISSUE THREE | 2017

R182 574 per month

2. Electricity in the region of R100 per kw/h

It would be the same as purchasing a Bentley… and being paid for driving it after the initial purchase.

3. Water It is often said that Eirich mixing technology is expensive – this could not

* The above example is based on tests and results conducted in Europe.

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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

ASSOCIATE MEMBERS ASPASA Tel: (011) 791 3327 PROVINCE/COUNTRY: GAUTENG

PI – Precast Infrastructure PB – Precast Building

PRECAST | ISSUE THREE | 2017

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