Precast

PRECAST VOLUME SIX ISSUE 1 • 2012

THE CMA – QUALITY CAST IN CONCRETE

• Concrete piping for massive infrastructure project • Extensive retaining wall project • UK flood alleviation scheme

CONTENTS

1

CONTENTS NEWS

23 SIKA SUPPLIES ADMIXTURES FOR

EARTH-CORE DAM

2

TECHNICRETE GEARED

FOR RISING DEMAND

3

CMA HOUSE PLANS NOW

AVAILABLE ON CAD

4

MAPEI APPOINTS NEW PERSONNEL

5

EASIER NAVIGATION ON REVAMPED

TERRAFORCE WEBSITE

27 ‘FUNDAMENTALS OF CONCRETE’ UPDATED

7

CMA ADOPTS FRESH APPROACH

27 FOXING EFFLORESCENCE

TO AWARDS FOR EXCELLENCE

28 CMA MEMBERS

24 CONCRETE BLOCK PAVERS –

THE PEOPLE’S CHOICE IN HEIDELBERG

25 CONCRETE SOLUTIONS FOR

UNDERGROUND CONSTRUCTION PROJECTS

26 NEW SUPER-SEALANT FROM MAPEI

8

CONCRETE TECHNOLOGISTS

NEEDED URGENTLY

11 PAVING STANDARD AMENDED 11 BIRKENMAYER APPOINTMENT

TECHNICAL NOTES 14 NEW CONCRETE BLOCK PAVING

STANDARD AMENDED

ARTICLES 12 EXTENSIVE RETAINING-WALL PROJECT

FOR NEW SHOPPING CENTRE

17 CONCRETE PIPING SPECIFIED

FOR INFRASTRUCTURE PROJECT

20 UK FLOOD ALLEVIATION SCHEME OPTS

FOR PRECAST CONCRETE ELEMENTS

APPLICATIONS 22 CONCRETE BLOCK RETAINING WALLS

PROTECT BURGERSFORT WAREHOUSE

22 PPC CEMENT USED FOR DE HOOP DAM

Our front cover shows a pipelaying operation at Waterfall City, Midrand, where close on 5 000m of precast concrete stormwater piping forms a major part of the site’s civil work. The pipes were specified by the Johannesburg Roads Agency (JRA) for what is seen as one of Gauteng’s largest infrastructure projects to date. Trench depths vary between 1.5m and 5.5m and with natural gradients as high as 1 in 20 in some places, 17 drop boxes are being built to reduce water velocities. See article on page 17.

PRECAST is the official journal of the Concrete Manufacturers Association (CMA) Block D, Lone Creek, Waterfall Office Park, Bekker Road, Midrand PO Box 168, Halfway House, 1685 Tel: +27 11 805 6742, Fax: +27 86 524 9216 E-mail: main.cma@gmail.com, Website: www.cma.org.za Publishers Isikhova Publishing & Communications PO Box 651793, Benmore, 2010, South Africa Tel: +27 11 883 4627, Fax: +27 11 883 4627 Website: www.isikhova.co.za Publisher: Andrew Meyer Tel: +27 11 883 4627, Cell 082 456 5175 E-mail: andrewm@isikhova.co.za Editor: David Beer Tel: +27 11 478 0239, Fax: +27 11 678 0254 E-mail: bigsky@ibi.co.za Advertising: Rui Chirindja Tel: +27 11 883 4627, Cell: 082 717 2851, E-mail: communications@isikhova.co.za Design, layout and production: Joanne Brook The views and statements expressed in this publication are not necessarily those of the editor or the publishers and neither he/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.

PRECAST VOLUME 6 • ISSUE 1 • 2012

TECHNICRETE GEARED FOR RISING DEMAND Production-line efficiencies combined with new quality levels mean that building-products manufacturer, Technicrete, is well placed to meet the demand from Government’s proposed spending on infrastructure.

“The multi-billion rand “shopping list” announced in President Zuma’s State of the Nation address, and echoed in the 2012 Budget, is good news for the construction industry,” says Technicrete MD, Albert Weber.

Technicrete is a member of the Murray & Roberts Building Products group and is one of the country’s largest producers of concrete building products, with eight strategically located manufacturing plants in Gauteng, Free State, Mpumalanga, Limpopo and North West Province. It produces an extensive range of concrete paving blocks and kerbing for heavy and light-duty roads, pedestrian routes, retaining wall systems, roof tiles, advanced erosion-protection systems, as well as mining products.

Weber says Technicrete already has an impressive record in infrastructural growth, having contributed significantly to improving the quality of life for many thousands of people in rural areas.

“In recent years, we have manufactured tens of thousands of paving blocks and kerbing in projects to upgrade hundreds of kilometers of roads and pedestrian routes - in some cases where no decent roads previously existed.”

A feature of Technicrete’s operations - especially in rural areas – is its close collaboration with emerging construction companies, he adds.

“These growing companies are benefiting greatly from Technicrete’s experience, technical know-how and training backup. We like to think of ourselves as partners in these upgrading projects, and our responsibility does not end with delivering the goods.”

Discussing the Government’s latest infrastructural spending blueprint, Weber adds, “We are encouraged to hope that the Government will really make it work, and that the building and construction industry will see money flowing in to create more jobs.”

Infrastructure in action: roads ugrade at Alldays Township near Polokwane generates work for local labour.

CMA HOUSE PLANS NOW AVAILABLE ON CAD Architectural plans for the 40m² CMA

dimension is accounted for and avoids the

House are now available on CAD. CAD-

time-consuming and wasteful process of

based plans can be down-loaded off the

chopping blocks to fit; if applied correctly,

Concrete Manufacturers Association

the process can generate substantial cost

(CMA) website at no charge.

and quality benefits.

Isia Ortner, the architect who designed

“Preparing plans for proper modular

the CMA House, says that placing the

masonr y is time consuming bu t the

plans into CAD software means that they

extra ef for t is definitely wor thwhile.

can be easily modified and will therefore

As most subsidy housing developments

have much broader appeal.

involve the construction of +- 50 if not

“There is no such thing as a totally

hundreds of houses, the additional costs

standard house even at the subsidised

that detailed modular-masonry plans

h o u si n g l e v e l . E a c h d e v e l o p m e n t i s

entail, are rendered insignificant through

different, if only minimally, and CMA House

amortisation. Moreover, when the savings

plans can now be easily adapted to suit

that accrue from modular masonry are

specific developments.

realised, the preparation of detailed plans

“For example, CAD allows for easy

becomes even more compelling.

orientation and makes future extensions

“This poses the question as to why

much easier. It also facilitates mirror

all subsidy housing developments are

imaging as well as the adjustment of

not built using modular masonry? The

internal layouts,” comments Ortner.

sad truth is that most subsidy housing

Unlike most subsidy housing plans

developers are too focused on securing

which are basic, the CMA House plans are

architectural plans at the lowest

fully detailed, down to the last concrete

possible cost, and in so doing, miss out

block in fact. Central to the whole CMA

on the cost savings and improved quality

House concept is modular masonry which

aspects that detailed plans for modular

requires that each and every block and

masonry entail.”

CMA House plans designed with the 290 solid block.

4

NEWS

MAPEI APPOINTS NEW PERSONNEL Mapei South Africa has made four new appointments.

L aur ence Gopane joined Mapei on 9 Januar y 2012 as senior technical consultant for its grinding-aids division.

Gopane holds a BSc (Ed) degree and has over 13 years experience as a quality-

Johan Venter has been appointed as

merce degree in marketing, and has worked

a sales consultant f or Mapei’s Cape

in the construction chemicals industry for

Town region.

four years.

Previously employed as sales & technical

Martin Olivier joined Mapei on 1 May

consultant before taking the role of sales

2012 as a national specification consul-

manager, Ven ter has o v er 10 y ear s

tant. Martin has a national diploma in

experience in the construction industry.

building science and began his career

assurance chemist, cement and concrete

Tanya Duvenage joined Mapei on 24 April

in housing. Prior to joining Mapei

laboratory supervisor, production and

2012 as a senior technical consultant for

he worked on cellular-tower construc-

quality superintendent, and as a technical

its extensive building range.

tion as a senior pr oject planner and

Duvenhage holds a Bachelor of Com-

consultant.

Laurence Gopane

Johan Venter

Tanya Duvenage

quantity surveyor.

Martin Olivier

EASIER NAVIGATION ON REVAMPED TERRAFORCE WEBSITE Terraforce, a Cape Town-based precast concrete licensor, specialising in modular, hollow-core concrete blocks, has announced a redesigned website.

Terraforce marketing manager, Karin Johns, says the new site provides a more cohesive web presence for its licensee network, and has improved the overall user experience for all other visitors to the site.

“Considerable thought has gone into our Web presence and we are delighted with the new design. Besides easier navigation, the site provides our clients and prospective clients with a practical access point where they can find important in f orma tion on our pr ecast modular concrete blocks, quickly and easily. The site also includes a comprehensive Q&A section, a PDF downloads page for technical manuals, bill of quantities, recommended specifications and detailed submission sheets, and an easy subscription to a monthly newsletter,” says Johns.

Terraforce takes pride in sustainable and attractive retaining wall design.

Terraforce’s licensees can now also be contacted through several Web-based platforms, as each licensee has been allocated a separate page. These pages allow Web users to contact licensees via email and they provide Google maps of each Terraforce associated business.

A completely new feature of the site is its social-media connectivity.

“Visitors can share content or follow Terraforce on LinkedIn, Facebook and Twitter. This makes the site considerably more interactive and turns it into a hub of information on the retaining wall industry in general,” comments Johns.

Johan van Wyk, MD of Cape Retaining Systems, a Terraforce block supplier added: “Many of our customers’ first contact with us is via the Terraforce website, as Terraforce is a household name in retaining walls. We are very excited as the new website will make it easier for potential clients to reach us. Social media, which is used increasingly by the IT generation, is a vital adjunct to those who want to share information, specifically in a dynamic

A sampler page of Terraforce’s website which can be accessed via www.terraforce.com.

environment such as the retaining-wall industry.”

CMA ADOPTS FRESH APPROACH ON AWARDS FOR EXCELLENCE Coinciding with its 40th anniversar y

Commenting further, Laing says that an

celebrations, the Concrete Manufacturers

awards entry book won’t be published this

Association (CMA) has announced that its

year. Instead all entries will be posted on

2012 Awards for Excellence competition will

the CMA’s website and on Facebook. As

be run on an entirely new basis.

in previous years a winners’ book will be

Unlike in the past when competition

published and distributed immediately after

categories were product-based, this year

the Awards which will be staged jointly

the emphasis is on the core values and

with the Association’s 40th anniversary

standards on which precast concrete

celebrations on November 3rd at the Indaba

products and applications are measured,

Hotel in Johannesburg.

and the new award categories reflect this.

These are as follows:

“The event presents an outstanding opportunity for all professionals involved

• Aesthetics

in the manufacture and application of

• Sustainability

precast concrete to establish themselves

• Community involvement

as trendsetters in their specific disciplines

• Technical excellence

C and to gain national recognition for their

• Innovation

achievements,” concludes Laing.

• Vintage Besides the new categories, the number

M

The deadline for entry submission is Y

June 29th and judging by constructionCM

of awards has been halved from 36 to

related professionals will take place in

18. Moreover, the thee-tiered structure

MY August. Award entry forms together with

comprising regional awards and ceremonies,

the competition rules can be downloaded CY

national awards and five trophy awards has

from www.cma.org.za .

been dropped. It is being replaced by a single streamlined ceremony in which trophies are awarded to the overall winner of each category; in addition three commendation awards per category will be made.

CMA director, Hamish Laing, says each category is open to entries from any construction project providing one or more precast concrete product manufactured by a CMA member has been used in its implementation.

“Entries will be judged on the contribution that precast concrete elements make in one or more of the competition’s categories.

In other words the same project could be entered for more than one competition category. For example, a township paving project could be entered into several if not all six categories.”

Laing says the standards on which the award entries will be judged this year will be as high if not higher than they always were, and awards will only be made if the quality of entries meet competition criteria.

In instances where standards are not sufficiently high, awards will be withheld,” says Laing.

CMY

K

8

NEWS

CONCRETE TECHNOLOGISTS NEEDED URGENTLY The biggest threat to the economic growth

Technology every two years under the

concrete, mining and also the cement,

of South Africa is the shortage of technical

auspices of the Institute of Concrete

aggregate, admixture, and ready-mixed

sk ills in engineering and technology,

Technology (ICT) in the UK.

concrete industries. Successful candi-

according to Bryan Perrie, managing

Delegates are drawn from qualified

dates will qualify for free membership of

dir ec tor o f the C emen t & C oncr e te

civil engineers, cement chemists, concrete

the Concrete Society of Southern Africa

Institute (C&CI).

technologists and technicians involved

while studying. The Society has officially

in the building, construction, precast

endorsed the course.

Speaking at a breakfast function in Midrand to mark the start of the C&CI School of Concrete Technology’s 2012 Advanced Concrete Technology ( AC T ) training course, Perrie said the shortage of qualified concrete technologists was a major component of the shortage of materials engineers in this country.

“The ACT course will, this year, expose delegates to a wide range of concrete disciplines and insights that could provide a competitive advantage to both delegates and their companies,” Perrie stated.

The globally-recognised ACT course is presented by the School of Concrete

The 21 delegates for the C&CI 2012 ACT class pictured with SCT lecturer, John Roxburgh (back row, extreme left).

A CONCRETE PAVED ROAD FOR ALL Quality paved roads for every setting.

Creating community skills development.

SABS approved product from CMA members.

For supply and technical advice visit the CMA website.

www.cma.org.za

For more information call our toll-free line on 0800 023 470 or visit www.ppc.co.za

amount of regular 32,5 N general-purpose cement. Imagine how much further your vision could go with 15% extra.

strength properties which allow you to make at least 15% more bricks or blocks of the same strength, compared with the same

You can now make 15% more bricks when you buy improved PPC SureBuild 42,5 N cement. SureBuild 42,5 N cement has improved

TJDR 51988

Dynamon NRG & Dynamon SP Solutions specially designed for the precast concrete industry

3Accelerated development of mechanical strength

of 3Optimisation production cycles and strong reduction of maturing cycles

To solve specific problems encountered in the precast concrete industry and to strongly contribute to the development of this sector, Mapei has developed the DYNAMON NRG and DYNAMON SP product ranges. These products are specifically intended for this type of application and are especially suitable for manufacturing self compacting concrete.

Facilities Management Exhibition Visit us at the

29 - 30 May 2012

stand B3

Sandton City Convention Centre

www.mapei.co.za

Contact us: +27 11 552 8476 or info@mapei.co.za ADHESIVES • SEALANTS • CHEMICAL PRODUCTS FOR BUILDING PRECAST VOLUME 6 • ISSUE 1 • 2012

NEWS

11

PAVING STANDARD AMENDED The new standard for the manufacture

majority of manufacturers which weren’t

of concrete block pavers (CBP) SANS

able to comply with the new standard

1058:2010 was of ficially amended by

consistently, even though a few had been

the South African Bureau of Standards

able to do so.

(SABS) on February 8, 2012 and is now known as SANS 1058:2012.

The upshot for CBP manufacturers is that Edition 2.0, which was f ir st

CMA director, Hamish L aing, says although the per formance criteria of Edition 2.1 are lower than Edition 2.0, they are only so marginally.

announc e d in Mar ch 2010 as S A NS

“Edition 2.1 of SANS 1058:2012 still

1058:2010 and then officially introduced

sets a higher quality benchmark and is

in September 2011, has been replaced by

considerably more comprehensive than

Edition 2.1 as SANS 1058:2012.

SANS 1058:2006,” says Laing.

The requirements for two of the three

In addition to the amendments, the

performance measurement techniques in

standard’s two strength ratings were

the new standard, tensile splitting and

renamed for greater clarity. These are

abrasion testing, have been lowered, and

Class 30/2.0, officially rated at 2.0.MPa

the third, a water absorption test, has

(tensile strength), and Class 40/2.6, rated

been placed on a voluntary footing.

at 2.6MPa (tensile strength).

BIRKENMAYER APPOINTMENT

Initiated by the Concrete Manufacturers

A n o f f i cial t e chni c al n o t e o n th e

Mr. Anthony Makgale has been appointed

Association (CM A ), the amendments

amendment is a v ailable on the CM A

as sales engineer at Birkenmayer in

wer e in tr o duc e d t o ac c ommo da t e a

website and page 14 of this issue.

Johannesburg.

12

ARTICLE

EXTENSIVE RETAINING-WALL PROJECT FOR NEW SHOPPING CENTRE One of the largest retaining wall projects ever undertaken in South Africa is currently under construction at Cradlestone Mall, a new shopping centre in Muldersdrift, which is being constructed for the Sasol Pension Fund and Retail Africa by Aveng Grinaker-LTA. Designed as gravity retaining walls by

built, including a perimeter wall around

and temporary 70º slopes have and are

the entire site and several walls within

being created in the dolerite sections prior

the site itself.

to erecting retaining walls. Excavated

Sloping ground has necessitated ter-

dolerite, which conforms to a G6 material

racing with cut-to-fill earthworks and is the

standar d, is being used f or the bulk

main reason why retaining walls are playing

earthworks fill.

such an important role in this project.

Before Diesel Power moved on site,

The Cradlestone Mall walls are being

geotechnical testing involving pits and

built by CMA contractor member, Friction

augered holes indicated no observable

Retaining Structures, working as a sub-

seepage. Despite this it was recom-

contractor for earthworks contractor,

mended that the retaining walls and the

Diesel Power.

fill behind them be rendered waterproof

Silvio Ferraris, CEO of concrete retaining

Site material consists predominantly

blo ck ( C RB ) m anu f a c tur er an d C M A

of residual dolerites and dolerites as

Drainage is being installed above the

member, ReMaCon Products, the walls are

well as some potentially collapsing soils.

finished levels directly against the cut

being built on a site situated between the

However, the latter are not expected to

faces. It consists of perforated 110mm

N14 highway and Hendrik Potgieter Drive.

be problematic. The dolerite constitutes

Just under 2 000m of walls are being

an acceptably stable founding material

PRECAST VOLUME 6 • ISSUE 1 • 2012

with good drainage.

Completed retaining wall sections at Cradlestone Mall.

ARTICLE

13

piping which is covered with 19mm stone.

sustained loading and it has a 27kN long-

contractor is essential to any successful

Both the stone and the piping are being

term design strength rated at 5% strain.

CRB wall project.

wrapped with A2 bidim to prevent soil

This means that in the unlikely event

“This prevents problems from

fines from clogging the stone. Bidim is

of any soil movement, the fabric will be

developing and solving those that do

also being laid against the cut faces to

sufficiently resilient to ensure that the

promptly and inexpensively. This aspect

prevent the possibility of any sub-surface

stretch factor won’t be greater than 5%

is working extremely well at Cradlestone

water from percolating through the soils

at maximum permissible strain.”

Mall,” concludes Ferraris.

and destabilising the walls. Any seepage

Commenting further, Ferraris said that

will be transmitted through geofabric into

in opting for CRB walls rather than vertical

the drains and this will prevent phreatic

in situ walls at Cradlestone Mall, at least

pressure from developing behind the walls.

50% was saved on costs and an additional

Varying in height between 1m and

60% on time.

10m, the walls are being built either as

“A v e r t i c a l w a l l r e q u i r e s a h u g e

cut-face or as bulk reinforced structures,

f oundation with steel r einf or cement

the latter using fill material and geofabric

and steel starter bars. It also involves

reinforcement supplied by Kaytech. All the

shuttering on both sides of the wall,

walls are being constructed at an angle

the pouring of wet concrete, waiting for

of 65º using 8 000m² of Terraforce L11

the concrete to set and stripping the

blocks, manufactured under license by

shutters. Then one still has to compact

ReMaCon. The same blocks are being used

the ma ter ial f ill behind the wall. B y

for the base courses, but in instances

contrast CRB walls are simpler and quicker

where the walls are higher than seven

to erect, and more attractive, especially

metres, the blocks are supplied in greater

when filled with plants.

strength ratings.

Risidual dolerties and dolerites at Cradlestone Mall are cut and excavated prior to reinforcing with concrete block retaining walls

“However, one has to weigh up the

Ferraris comments that flatter walls

additional cost of vertical walls versus

are less imposing and more attractive

the space they save. When space is at a

and that walls steeper than 70º require

premium and the cost of land extremely

considerably more engineering.

high, the additional cost of vertial walls

He says that geofabric reinforcement is

P

can sometimes be justified.”

being used on walls six metres and higher.

Ferraris advises that communication

“Minimum geofabric depths begin at

and cooperation between the earthworks

three metres and vertical spacing varies

contractor and the retaining-wall block

Partially completed earth-works and retaining wall sections seen here at Cradlestone Mall.

from 450mm to 900mm, depending on wall heights. Up to 15 layers are being used on the highest walls.

“Because the terraces are soil-filled, geofabric is installed to intersect soil planes and the designer must ensure that the combined force of the geofabric is greater than that exerted by the soil. The type and depth of fabric is determined by the wall angles. SANS 207 states that if the angle is less than 70º, geofabric with a 5% strain can be used. In such instances the geofabric is allowed to stretch by 5%, which at Cradlestone Mall means that the angles of the walls can steepen from 65º to 68,2º. However, this is unlikely to happen due to the good quality of on-site fill material and the shear interaction between the soil and geofabric.

“The geofabric specified for Cradlestone Mall is Kaytape woven polypropylene S270 with a short-term rating of 50kN. It is designed to stretch and creep under

One of several retaining walls which follow the contours on the cut-to-fill earthworks project at Cradlestone Mall.

PRECAST VOLUME 6 • ISSUE 1 • 2012

TECHNICAL NOTES

NEW CONCRETE BLOCK PAVING STANDARD AMENDED The official standard for the manufacture of concrete block pavers (CBP) SANS 1058:2012 has been amended.

COMPARISON OF OLD AND NEW SPECIFICATIONS

With effect from February 2012, Edition 2.1 replaced Edition 2.0, which was first announced in March 2010 and became official in September 2011. This was the 18-month window period for manufacturers to alter their mix designs and production processes in compliance with the new standard.

Initiated by the Concrete Manufacturers Association (CMA ), the amendment was made to accommodate a majority of manufacturers which weren’t able to comply with the new standard consistently, even though a few were able to do so. The performance criteria of Edition 2.1 ar e ther ef or e lower, albeit only marginally. Edition 2.1 of SANS 1058:2012 still sets a higher quality benchmark and is considerably more comprehensive than the standard it replaces.

In addition to the amendments, the standard’s two strength ratings were renamed for greater clarity.

However, to help the industry better understand the new per formance measurements, SANS1058:2012 still refers to the old compression standard, even though it does not form part of the new standard.

Unlike the old standard, SANS1058-2006, which relied on a single, compression based measurement, SANS1058:2012 includes two new performance measurement techniques: tensile splitting and abrasion testing.

The CMA made a conscious decision to increase the performance requirement of quality concrete block pavers in drafting the new standards in collaboration with SABS and to this end, two upgraded strength ratings were added.

Class 30/2.0, officially rated at 2.0MPa (t ensile s tr eng th ), is indic a ti v e o f a c o m p r e s si v e s t r e n g t h r a t in g o f around 30MPa, and Class 40/2.6, rated at 2.6MPa (tensile strength), approximates a compressive strength rating of about 40MPa. Unfortunately there is not a direct correlation between the tensile and compression strength of a concrete block paver. This relationship varies depending on aggregate type, shape and grading and the amount of vibration available during manufacture.

For specification purposes, Class 30/2.0 replaces the old class 25 of SANS10582006, which was based on a compressive strength rating of 25MPa, and Class 40/2.6 replaces the old Class 35 based on a compressive strength rating of 35MPa.

A set of paving blocks after a run on the abrasion testing machine.

Tensile splitting is a far more appropriate performance measure than compressive testing because it measures resistance to cracking and break-ups as opposed to resistance to crushing.

Research has shown that paving blocks are hardly ever crushed under load whereas cracking and break-up as well as abrasion are the main causes of paving failure. The tensile-split test involves applying line loads to the top and bottom of the blocks using two steel bars, each with a diameter of 150mm. Plywood strips are inserted between the bars and the blocks to ensure an even load distribution. More importantly, the test takes the thickness of the block into account whereas thickness was not a factor in compression testing.

It is known that paving blocks with good strength ratings do not necessarily provide good abrasion resistance, which is why a surface-wear test has been included in the new standard.

Abrasion is specific to the quality, density, shape and particle distribution of the aggregates used in the topping layer

and the percentage binder. For example, a paving block with a high strength rating can have low abrasion resistance.

Conversely, a block with a low strength r ating can have excellent sur f acewear properties.

Most South African paving producers manufacture pavers with two layers.

The bottom and thicker sections provide the required strength. The top layers, w hich ar e a t le ast as str ong, ar e coloured with pigments for enhanced aesthetic appeal.

Now that the new standard measures abrasion r esistance, these topping layers are being designed with excellent surface-wear properties. Even lowergrade blocks with a good topping layer can of fer high abrasion resistance, providing the topping layers do more than offer colour variation.

It is important to note that pedestrian traffic is highly abrasive, more so than most other forms of traffic.

As part of its research for the new standard, the CMA investigated all forms

Abrasion testing machine.

of abrasion resistance, testing various systems around the world. In the end, it opted for the Australian/New Zealand model, which proved to be suited to in-situ performance conditions. The amendments to SANS1058:2012 restrict the average mass loss per block to 15g after being pounded by 600 16g ball bearings for 60 minutes in a rotating steel box.

A water absorption test had been included in the original SANS1058:2010 because CBP with low absorption rates tend to offer better durability but the test has been dropped in the amended standard. The denser a block the lower its water absorption rate and a block with good density will almost invariably pass the tensile-splitting test. The absorption test was first introduced in Europe to prevent blocks from shattering when frozen. Although the requirement has been left out of the amended SANS1058:2012, it remains an informative and voluntary part of the standard.

It is strongly recommended that both private and public specifiers adopt the revised standard as soon as possible and that block users check compliance with the new standard prior to ordering.

A tensile spilt test underway.

FOR MORE INFORMATION, CONTACT THE CONCRETE MANUFACTURERS ASSOCIATION (CMA) Block D, Lone Creek, Waterfall Office Park, Bekker Road, Midrand • PO Box 168 Halfway House 1685 Tel: +27 11 805 6742 • Fax: +27 86 524 9216 • E-mail: main.cma@gmail.com • Website: www.cma.org.za

ARTICLE

Recently laid 650mm concrete piping prior to being connected by an in situ built manhole.

Sections of 650mm concrete pipe are aligned with laser beams prior to joining and sealing.

17

Two 1 650mm stormwater concrete pipes prior to being connected by an in situ-constructed drop box.

CONCRETE PIPING SPECIFIED FOR INFRASTRUCTURE PROJECT Just under 5 000m of precast concrete stormwater piping is what it will take to drain Waterfall City, currently under construction and earmarked to become Midrand’s new central business district. The concrete pipes were specified by the Johannesburg Roads Agency ( JRA) for what is seen as one of Gauteng’s largest infrastructure projects to date. Driven by Atterbury Property Developers, the initial development will comprise 800 000m² of letable space when completed in 2018.

supplied by two Concrete Manufacturers Association (CMA) members, Rocla and Southern Pipeline Contractors.

Infrastructural work began in 2009 when aerial sur veys established land gradients. Labucon moved on site in 2011 where it will remain until the completion of all infrastructure work in August 2013.

This includes the construction of some six kilometres of roads and the laying of

Spanning 125 hectares, the site forms

A section of 650mm concrete piping is covered with soil after laying and joining. A layer of bidem sheeting which is installed to prevent excess water from penetrating beneath the road surface can be clearly seen on the right.

4 985m of concrete stormwater piping.

part of a 565 hectare estate (formerly

The stormwater piping project began in

owned by the Mia family) bordered by

November 2011 and will be completed in

Allandale Road , the Johannesburg/Pretoria

November 2012. The pipes, in diameters

highway, Woodmead and a mushroom farm.

from 450mm to 1 950mm, will drain

Infrastructural planning and project

the site and discharge into three water

management is being undertaken by C-Plan

channels which will ultimately feed into the

Consulting Engineers. Earthworks, road

Jukskei River to the south.

infrastructure and the installation of

Trench depths vary between 1.5m and

stormwater, fresh water, and sewerage

5,5m, and with natural gradients as high

piping falls to Labucon Resources, while

as 1 in 20 in some places, 17 drop boxes

the concrete stormwater pipes are being

are being built at T junctions and at bends

PRECAST VOLUME 6 • ISSUE 1 • 2012

18

ARTICLE

Trenching and stormwater pipe laying at Waterfall City.

One of the infrastructure plans for Waterfall City.

to reduce water velocities. In addition

providing additional founding stability for

manholes are being constructed in all

the pipes and blasting is breaking up the

other places where there is a change of

rock which is then crushed and used as

pipe direction.

dump material for a road-building project

A c c o r din g K C O o ij k a a s o f C - P l a n

Sias Swart, contracts manager, says

being built to Johannesburg Roads Agency

the stone bedding pr events any soil

( JR A ) standar ds f or which concr ete

movement from exerting excessive stress

stormwater piping is mandatory.

on the pipe joints.

“Precast concrete is the best material

“We are also using a laser-beam system

for stormwater drainage, which is why

to ensure that the pipes are properly

it forms part of the JRA road-building

aligned,” says Swart.

specifications,” says Ooijkaas.

Two 1 950mm pipe sections prior to being connected by an in situ-built manhole.

on an adjacent site.

Consulting Engineers, all the roads are

The pipes are connected with ogee

Besides fairly steep gradients, other

joints. These are rendered water-proof

engineering challenges included outcrops of

through the application of a water-based

rock and a high-water table. Stone bedding

damp seal to the joints and on 20mm of

comprising 19mm imported aggregate is

piping surface on either side of the joints.

This area is then covered with A4 bidem sheeting and a second coating of damp seal.

Bidem sheeting is also being installed on the land embankments which rise above the pipes so that excess ground water is prevented from penetrating beneath the road surface material, in this instance bitumen. Instead, water will be trapped by the bidem and channelled into perforated 160mm PVC pipes, which run parallel to the stormwater pipes, before discharging their contents into the manholes. To prevent them from being clogged with soil, the PVC pipes are covered with 19mm stone and wrapped in bidem.

Wingwalls are being installed where the pipes discharge into the water channels to prevent soil ereosion. However, the

An aerial view of the Waterfall City site.

PRECAST VOLUME 6 • ISSUE 1 • 2012

Waterfall City project is setting a prec-

ARTICLE

19

edent in that two of its wingwall outlets

CM A dir ector, Hamish L aing says

are not being constructed on site. Rather

that besides its durability and long life-

when working in trenches.

“There is a great deal of knowledge on

they have been factory-built in precast

span, concrete piping is far less depend-

concrete and its related performance, as

concrete by Rocla.

ent on embedment material than a flexible

opposed to new piping materials on which

Recently introduced to the local market

pipe. Because concrete piping is rigid,

field knowledge is scant. If you want value

by Rocla, and JRA approved, precast

contractors don’t incur the same sort

for your money, and aim to get it right

wingwalls offer several advantages such

of difficulties as they do with the proper

first time, concrete is the route to go.

as very much quicker installation, a lower

installation of flexible pipe products. These

We can’t afford to have reworks in South

material requirement, no formwork and

difficulties become even more pronounced

Africa,” concludes Laing.

no waste. They are installed by crane, and depending on gr ound conditions, take between 15 minutes and an hour to install. By contrast, in situ wingwalls take a minimum of two days to construct and seven days to cure and can also be adversely affected by rain shortly after construction.

Craig Waterson, sales and marketing director of Rocla, says that in stormwater applications, wingwalls direct the water into a flow path that will result in the least amount of turbulence, thereby optimising the hydraulic capacity of the conduit.

“P r e c a s t w i n g w a l l s c o m e w i t h a separate precast concrete toe which keys the entire unit to the ground and prevents any movement. The toe also reduces the risk of soil scouring below or to the side of the toe,” says Waterson.

A five-ton precast concrete wingwall and concrete toe prior to installation at Waterfall City.

P

20

ARTICLE

Precast wave wall being unloaded and ready to be placed.

Lifting the concrete ‘mattresses’.

UK FLOOD ALLEVIATION SCHEME OPTS FOR PRECAST CONCRETE ELEMENTS The north-east coastal town of Redcar lies on a naturally eroding coastline and has in recent years suffered from significant breaches in its sea wall. Flood modelling estimates show that 978 homes and 209 business premises are at risk of sea flooding. Without improvements to the sea defences a further 184 residential and 98 commercial properties would be at risk within the next 100 years. Brian Farrington of Birse Coastal reports.

the natural ‘Scar Rocks’ formation, which

Birse Coastal worked closely with the

of coast protection in order to meet the

Environment Agency, Redcar and Cleveland

required standard of protection against

Borough Council, designers, architects

flooding.

This article first was published in February by Concrete, a UK-based journal which covers various aspects of concrete usage.

also provides an important feeding ground for visiting birds. As a result, the finished works and also the method and timing of the work required close consultation and agreement with Natural England.

The scheme is split into two distinct sections that require different methods

and suppliers during an extensive Early T he Redcar Flood Alleviation Scheme

Contractor Involvement (ECI) phase. The

Specially designed

involves protecting a 2.7km stretch of

ECI process is a key part of developing

The 1.5km esplanade will be protected by a

coastline from Coatham Boating Lake in the

high-quality sustainable solutions that can

specially designed precast stepped concrete

west, along the esplanade in the centre of

be constructed safely and with minimum

revetment with a precast reinforced

town and The Stray to the east.

disruption to the local community.

concrete curved wave return wall on the

For over three years prior to the

The site also sits within a Site of Special

scheme reaching construction stage

Scientific Interest (SSSI) area containing

PRECAST VOLUME 6 • ISSUE 1 • 2012

top and a steel pile or concrete beam at the toe, which provides scour protection.

ARTICLE

21

The precast units are being manufactured by Macrete at its facility in Ireland and shipped by road via Heysham. As the new sea defence is also an integral part of the regeneration of the promenade, not only was a high-quality finish required but also the curved wave walls use a buffcoloured concrete to complement the finishes on the promenade and match the natural beach colour.

Re-landscaping the seafront

significant benefits to coastal schemes

As well as replacing the sea defence in this

through the use of its modern fleet of

section, Birse Coastal is working together

cranes and its expert operators.

with Redcar and Cleveland Borough Council to re-landscape the seafront, creating an

Technological development

enhanced visitor experience and amenity

One particular technological development

area for residents and tourists. This will

came through discussion on a previous

include leisure and entertainment spaces,

scheme with Blackpool Tower operators

water-play areas and quiet areas where

about materials and maintenance systems

the atmosphere and natural wildlife can be

they use in the tower lifts. As a result,

enjoyed. It also incorporates high-quality

BPH Equipment has increased its use

coloured precast concrete steps laid out to

of multi-core compacted wire rope on

give the impression of a long ‘wave’ effect.

cranes instead of the three-core wire

Placing wave wall and completed section in place.

T h e f ir s t a r e a o f t h e si t e t o b e

rope used traditionally. This, together

problem for cranes working for lengthy

constructed on the scheme invol ved

with a forensic inspection regime and the

periods in coastal environments.

placing some of the largest precast units

use of a high-specification rope lubricant,

The 1.2km Stray requires a slightly

ever installed by Birse Coastal. These were

has signif icantly r educed the risk of

reduced standard of protection due to

the 6m-high walls that surround the old

corrosion and associated maintenance

the natural sand dune system that forms

nightclub site, with the largest precast

costs, which had traditionally been a

a barrier between the roadside housing

units weighing in at an impressive 28 tons.

and the sea.

Detailed planning and sequencing of precast

This area will be protected by repairing

unit manufacture, delivery and storage with

the existing groynes, overlaying the current

supplier Macrete is required to ensure

sloping defence with a precast concrete

construction progresses smoothly. The

mattress, constructing a short section of

close working relationship with sister

flood defence wall beside the paddling pool

company BPH Equipment has provided

and creating a new promenade.

Programme restraints T h e r e a r e signi f i c an t c h all e ng e s t o overcome while constructing the scheme, including programme constraints that limit both working areas and the times of year that par ticular areas can be accessed. For example, the town centre area needs to be kept free for tourists to use during the summer season and working hours are restricted at the west end of the scheme either side of high tide so as not to disturb visiting birds, which congregate in the boating pool area when the tide is in. The £21 million project started in January 2011 and should be complete and ready for residents and

Mattresses and revetments in place

visitors to enjoy in early 2013.

P

PRECAST VOLUME 6 • ISSUE 1 • 2012

22

APPLICATIONS

CONCRETE BLOCK RETAINING WALLS PROTECT BURGERSFORT WAREHOUSE

Small said that during construction, high-tenacity, polyester-coated woven reinforcing grids were installed at every third block and that the tieback length of the grid was equivalent to 80% of wall heights.

A 146m concrete block retaining (CRB)

was undertaken to create space for the

Moreover, soil compaction levels one

wall which reaches a maximum height of

geosynthetic reinforcement of the walls

metre in from the external wall face were

8,5m, has been built for Amidad Trading

and the excavated soil was stockpiled for

carefully monitored during construction

using Aveng Manufacturing Infraset’s

re-use as backfill material. There were also

to ensure that the blocks wouldn’t be

Ridgeblok® at new warehouse premises

outcrops of rock in some sections of the

pushed forward during the lifespan of the

in Burgersfort, Mpumalanga.

embankment and compressors were used

walls, as this would steepen the angle of

to break it up,” said Small.

the wall faces.

A second wall, three-metres high and 55m long, was built on the same site with

Actual construction began by laying

Small advises that a good drainage

Aveng Manufacturing Infraset’s Terrace

base blocks at 85º on top of the foundations

system is essential to the proper

Blok® TB300 and TB490 retaining blocks.

which were 100% level. This created a level

functioning of a retaining wall.

Designed by TMV Consulting and built by

base and the desired starting point five

Engineered Interlock Solutions, the walls

degrees off the vertical.

“Drainage of the Burgersfort walls was achieved through the installation

were erected to protect embankments

of perforated pipes covered with 19mm

adjacent to the warehouse.

s t o n e an d w r ap p e d w i th n o n -w o v e n

Brennan Small, Aveng Manufacturing

polyester sheeting. A needle-punched

In f r ase t: L andsc ape Pr oduc ts sales

geotextile fabric was laid against the back-

manager, comments that the walls were

face and drainage outlets were installed

erected at steep 85º angles in order to

at three-metre intervals. Furthermore,

free up as much space as possible for the

250 wick drains were installed against the

construction of the warehouse.

“The site is situated on a fairly steep slope and a level platform was created by excavating into the slope.

“Further cutting into the embankment

back-face to collect any sub-surface water Reaching 8,5m at its highest point and stabilising a 146m embankment, this concrete block retaining (CRB) wall was built for Amidad Trading using Aveng Manufacturing Infraset’s Ridgeblok® at new warehouse premises in Burgersfort, Mpumalanga.

behind the reinforced backfilled sections.”

Small concluded by saying that the pr oject complied with all SA NS 207 requirements.

PPC CEMENT USED FOR DE HOOP DAM Southern Africa’s largest cement supplier,

been used, the latter having enhanced

PPC Cement, is supplying cement for the

cement yields by 15%.

construction of the De Hoop Dam in Lim-

“Owing to an overwhelmingly positive

popo. PPC will continue to do so over the

r esponse on OP C 52.5N cement we

duration of the four-year project which is be-

proposed its use for the De Hoop Dam to

ing run by the Department of Water Affairs.

the Department of Water Affairs and it has

Situated on the Steelpoort River, the

been used on the project since July 2011.

dam wall will be close on 85 metres high

“The enhanced OPC cement has been

and contain around 1.125 million cubic

formulated to enable end-users to produce

metres of concrete (700 000m³ when

cost-e f f ec ti ve concr ete and r elated

compacted) on completion in March 2013.

products, and through stringent quality

PPC had supplied 77 517 tons of cement

con tr ol me asur es, the new pr oduc t

at the time of writing.

ensures consistent performance.”

Marius Joubert, PPC area sales man-

Johan van Niekerk, Depar tment of

ager, says the project demonstrates PPC’s

Water Affairs site manager comments:

flexibility in meeting stringent deadlines

“We are extremely happy with the enhanced

and an ability to produce vast quantities

OPC product as it has been one of the

of cement.

contributing factors to the success of the

“Cement for the dam was supplied from

project. We have also received exceptional

our Dwaalboom factory in Limpopo and our

support from PPC’s technical specialists.”

Hercules plant in Pretoria. Both OPC 42.5N and the enhanced OPC 52.5N cement has

PRECAST VOLUME 6 • ISSUE 1 • 2012

The new De Hoop dam wall which is being built with PPC cement.

SIKA SUPPLIES ADMIXTURES FOR EARTH-CORE DAM Sika’s SikaPlast-V210 concrete admixture has been specified

by MBB Consulting Engineers for the construction of the first phase of Ludeke Dam, in Mbizana, Eastern Cape.

A multi-purpose water reducer and super plasticizer incorporating Sika’s ‘ViscoCrete’ polycarboxylate polymer technology, SikaPlast-V210 was used to construct the intake towers and the spillways. Selected for its versatility, good slump retention and optimised mix design, the product contains no formaldehyde, calcium chloride or any other chlorides, and as such will not initiate or promote the corrosion of steel in the concrete.

Due to substantial steel reinforcement, 580m³ of concrete had to be poured continuously into the base of the intake towers, a process which took 27 hours, far longer than any standard concrete pour.

The dam, pump station and rising main form the rawwater components of the Mbizana Bulk Water Supply Scheme initiated by Umgeni Water. The wall is 240m long and almost 40m high and the dam’s maximum storage capacity is in excess of 14.5 million cubic metres, providing much needed supply to 266 000 people in surrounding communities. Budgeted to cost R218 million, this is one of a very few earth-core dams in the country. The dam wall comprises a clay-cored rock-fill embankment with a concrete-lined side-channel spillway.

The pump station will supply water through a 13.9km steel pipeline to an existing water treatment works. The estimated earthworks volume is approximately 600 000m3.

An unseasonably high winter rainfall has posed additional challenges for the contractor, Rumdel Cape, which had to waste valuable construction time draining excess water.

The project is scheduled for completion in September this year and Sika will be supplying many more litres of SikaPlast V210 as well as several of its other high performance products.

The Ludeke Dam wall under construction.

24

APPLICATIONS

CONCRETE BLOCK PAVERS – THE PEOPLE’S CHOICE IN HEIDELBERG The use of concrete block paving (CBP) as a road-paving material in townships is widespread, certainly much more so than most realise.

The Concrete Manufacturers Associa-

One of the CBP roads laid by community members in Ratanda, a township in Heidelberg (Lesedi).

tion (CMA) has done some research into CBP township sites scattered across

aspects were other considerations which

he was initially responsible for designing

the country in diverse locations such as

influenced our CBP decision and our tender

the roads himself, but that as from 1996,

Rustenburg, George, Stilfontein, and Dur-

process ensures that all concrete paving

the volume of work meant that external

ban. Long-term and ongoing, most of them

blocks and concrete kerbing materials are

consultants were required, and since then

were initiated after 1994, and besides pro-

SABS approved.”

consulting engineers have been appointed

viding low-maintenance and highly durable

An interesting aspect of Heildeberg’s

road surfaces, are creating much needed

CBP initiative is that in addition to the

Much of the recent civil work has been

work for and the transfer of skills to local

township projects some suburban roads

handled by Century Civils, a specialist

communities.

have been surfaced with CBP as well. These

earthworks company, whereas local sub-

include upmarket Jordaan Park and middle-

contractors employing local community

income Heidelberg Ext 9.

members have laid the paving and installed

One initiative about which very little had been heard until recently is situated in

each year.

Heidelberg (Lesedi), Gauteng, where some

“Besides features such as exceptional

the kerbing. Training is given to new

90km of township roads have been paved

durability and labour intensity, CBP’s

recruits and refresher training courses

and kerbed over the past 17 years.

superior aesthetics is what swayed our

are also given by various accredited service

For example, all the roads in Ratanda

decision for suburban use,” said Aufmkolk.

providers when required.

Ext 7 and Heidelberg Ext 23 have been

Commenting further Aufmkolk said that

Most of the roads are five metres wide,

surfaced with CBP, and these projects

although some span 7.4m and wider. The

are due to be completed in 2012/13. A

material composition of most of the roads

more recent project, Jameson Park, was

comprise: a compacted sub-grade (in situ

completed in January. Currently, CBP road

material); a sub-base of stabilised gravel;

work is taking place at Impumelelo and

and the paving blocks.

paving will begin in other townships as and

“Collapsing soils and water presented

when funds become available.

problems on some of the roads and in these

Peter Aufmkolk, paving project manager

instances soil up to a depth of two metres

for the Lesedi Local Municipality, says the

was excavated. We replaced the soil with

main motivation behind the CBP project was to create jobs for the town’s local

A road surfaced with concrete block paving in Ratanda Ext 8, a Heidelberg (Lesedi) township.

communities.

stone and layers of gravel 150mm deep,” said Aufmkolk.

CMA director, Hamish Laing, says that

“Municipalities are under tremendous

one of the advantages of CBP, as opposed

pressure to create work and the labour-

to asphalt road surfaces, is that the paving

intensive nature of CBP not only addresses

block forms part of the structural layer.

this challenge but fits in with Government’s

This means that the sub-base layer doesn’t

E x p a n d e d P u b li c Wo r k s P r o g r amm e

have to be as thick.

(EPWP). There is massive unemployment

Aufmkolk says Heidelberg’s CBP project

in this area and although paving projects

will continue until close on 100% of its

create work for a limited number of people

township roads are paved with CBP.

over short periods, it is highly valued by community members.

“The low-maintenance and high-durability

PRECAST VOLUME 6 • ISSUE 1 • 2012

“It’s a win-win situation for the comOne of several CBP roads in Jordaan Park, an upmarket suburb in Heidelberg (Lesedi).

munity and the Lesedi Local Municipality,’ concludes Aufmkolk.

CONCRETE SOLUTIONS FOR UNDERGROUND CONSTRUCTION PROJECTS Underground mining operations in South Africa can undertake numerous construction projects swiftly and cost-effectively, by making use of a range of concrete-placer pumps manufactured locally by SEM Concrete Pumps, which forms part of the PMSA group of companies.

SEM general manager, Sarika Lutchman, points out that SEM specialises in the manufacture of concrete-placer pumps that are specifically designed for use in underground mining applications.

“SEM concrete placer-pumps are air-operated, making them ideal for underground mining applications.”

Lutchman notes that SEM concrete-placer pumps are used in underground mines for several applications, which include shaftsinking and lining, the construction of ore passes, dam walls or settlers, foundations and support structures.

SEM concrete placer-pumps include the wheel-guided SEM 100 with a 100l per-batch capacity, a maximum output of 6m³ per hour and a maximum pumping distance of 100m horizontal or 18m vertical.

“With a headspace of 140cm and a weight of just 235kg, the SEM 100 is easily transportable, even in the most restricted areas.

The SEM 100’s impressive production output, combined with its compactness and ease-of-use, has proven particularly popular among the largest names in the mining industry,” notes Lutchman.

The second model in the SEM concrete placer pump range is the SEM 250, which has a 250 litre capacity-per-batch, a maximum output of 19m³ per hour and a maximum pumping distance of 150m horizontal or 18m vertical.

“The SEM 250 is generally used where relatively large outputs are required, but where headroom or access is restricted underground. The SEM 250 is supplied either on a fixed stand or on a two-wheel site trailer,” Lutchman advises.

For further information contact Quintin Booysen on 086 100 7672 or on quintin@panmixers.co.za. Web: www.pmsa.com

Underground concrete pumping.

26

APPLICATIONS

NEW SUPER-SEALANT FROM MAPEI

Mapeflex Blackfill is not recommended for use in areas that carry pedestrian or vehicle traffic, nor for compressive, tensile, continuous or snap-shear stresses.

Mapei, an industry leader in construction

construction features on flat and

and concrete technology, has introduced

sloping roofs, including flues,

Mapef lex Black f ill, a one-component,

skylights, aerials and guttering

flexible, bituminous sealant, to the local

• Collaring around pipe-work

solid and free of dust, loose particles, oil,

building and construction market.

• Filling joints, cracks and gaps of

grease, wax, and old paintwork.

This innovative sealant is manufactured

any size.

For the best results with Mapeflex Blackfill, surfaces should preferably be dry,

“If the product is applied to damp or wet

from polymers with a sof t solvent

The product is not prone to leaching

substrates, any stagnant water should be

consistency and is ideal for quick sealing

and does not dissolve in water, allowing

removed and the product must be applied

and repair applications for most surfaces.

immediate exposure to rain after application

by pressing it sufficiently. Moreover it

“Due to its soft consistency, Mapeflex

and does not run or drip, even when applied

should not be used in temperatures below

in wide sloping or vertical joints.

5°C,” says Nieuwoudt.

Blackfill forms a plastic mass that is easily extruded and shaped. The product bonds to most substrates, such as cementitious material, wood, bricks, metals and a number of plastics,” says Paul Nieuwoudt, product manager for Building Systems, Mapei South Africa.

Applications of Mapeflex Blackfill include: • Localising seals on old bitumen

membranes without the laborious task

of getting specialised heating

equipment and gas on site

• Overlapping and filleting-in bitumen membranes • Sealing air vents • Immediately sealing gaps between

Mapei’s innovative bitumen sealant, Mapeflex Blackfill.

APPLICATIONS

27

‘FUNDAMENTALS OF CONCRETE’ UPDATED The updated, second edition of the Cement

architecture and other practitioners who

fresh and hardened concrete, mix design

& Concrete Institute’s acclaimed reference

require a working knowledge of the subject.

and proportioning, quality control and sta-

book, Fundamentals of Concrete, is now

The new 308-page edition - which con-

tistics, formwork, reinforcement, manufac-

tains many full-colour illustrations - has

ture and handling of concrete, sand-cement

First published in 1998, the book is

been updated and extensively expanded,

mixes, appearance of concrete and special

intended for students of engineering,

and now covers sustainability, concrete’s

concretes. For more information and or-

building management, quantity surveying,

constituent materials, the properties of

ders, contact publications@cnci.org.za.

available from the Institute.

FOXING EFFLORESCENCE Roof-tile manufacturer Coverland, the South

CHRYSO®Pareflo 20 reduces efflores-

African brand of the global Monier Roofing

cence and does not affect the strength of

corporation, is using CHRYSO®Pareflo 20,

the concrete. It is a long-lasting solution

a water-repellent efflorescence reducing-

that is ideally suited to precast applica-

agent, manufactured by Chryso.

tions such as roof tiles. The admixture

Efflorescence is an aesthetic problem

reacts with the cement matrix, creating

which presents as a white, chalky deposit

a polymer network that fills the capillar-

on concrete. It is caused by the migration

ies with concrete thereby preventing the

of soluble salts (capillary action) to the

migration of soluble salts to the surface.

surface where it crystalises to form an unsightly sediment.

“A cid w ashing is th e tr a di tion al approach to preventing efflorescence in

“Although ef florescence causes no

the precast industry. However, it is not

structural damage and is often removed

ideal because of potential health, safety

by the natural process of weathering (like

and environmental issues. Sustainability is

rainwater washing over tiles), Coverland

fundamental to Coverland and we respect

is taking taken every possible step to

the environment in our manufacturing

counteract it. We pride ourselves on our

pr ocesses. CHR Y SO®Par ef lo 20 has

quality and our roof tiles must be flawless.

assisted us in adhering to this principle.

Ef florescence occurs most commonly

“In addition to possible health and envi-

during the first week after production,

ronmental threats, acid washing also slows

the period when they are usually delivered

the production process. By contrast, by

to our customers,” explains Willem Grove,

using a minimal amount of CHRYSO®Pareflo

marketing manager of Monier South Africa.

20, the production process is faster and

Willem Grove, marketing manager of Monier South Africa.

safer. There is also a significant cost benefit involved,” says Grove.

Another impor tant function of CHRYSO®Pareflo 20 is that it acts as a water repellent because it reduces capillary absorption. Coverland’s rain test involves

running water for two hours

over16 roof tiles. With tiles produced using CHRYSO®Pareflo 20, there is a noticeable water-beading effect and this helps to ensure that water penetration is kept to minimum acceptable standards.

An

Coverland’s ‘Rain Roof Test’.

added

benefit

of

using

The tile on the left was manufactured without CHRYSO®Pareflo 20 and the tile on the right was manufactured with CHRYSO®Pareflo 20.

CHRYSO®Pareflo 20 is that tiles have a

always strives to create products with

much richer colour.

the lowest environmental footprint and

“A s the oldest concr ete r oo f tile

the highest quality. CHRYSO®Pareflo 20

manufacturer in South Africa, Coverland

is a way to achieve this,” concludes Grove.

PRECAST VOLUME 6 • ISSUE 1 • 2012

28

CMA MEMBERS

PRODUCER MEMBERS M = Masonry

COMPANY NAME

P = Paving

Pi = Pipes

TELEPHONE

ARW Concrete Holdings

(082) 850 3512

A Fick Cement Works Bafokeng Concor Technicrete Baybrick Beta Tiles

R = Retaining Blocks

PRODUCT

S = Floor Slabs

COMPANY NAME

T = Roof Tiles TELEPHONE

PRODUCT

R

Mobicast Mossel Bay

(044) 874 2268

P

(022) 913 1921

M

MVA

(012) 386 0050

P

(014) 538 0818

MPRT

Monier Roofing South Africa (H.O.)

(011) 222 7300

T

(035) 792 5218

P

Monier Roofing South Africa

(016) 430 8000

T

002634 2925303

T

Monier Roofing South Africa (Free State)

(051) 432 5089

T

Boland Concrete

(021) 875 5365

M

Monier Roofing South Africa (North West)

(012) 250 2218

T

Bosun Brick Brits

(012) 250 1711

P

Monier South Africa (Cape Town)

(021) 534 1441

T

Bosun Brick Midrand

(011) 310 1176

MPR

Monier Roofing South Africa (DBN)

(031) 565 1312

T

Brickcast Industries

(031) 507 5525

MPR

Monier Roofing South Africa (ELN)

(043) 743 2191

T

Brickbuild T/A Panda

Monier Roofing South Africa (George)

(044) 878 1325

T

Monier Roofing South Africa (PE)

(041) 463 2629

T

(046) 624 3377

MPRS

(00267) 244 2106

MP

Cape Brick

(021) 511 2006

MPR

C.E.L. Paving Products

(021) 905 5998

P

Neat Contech

Cast Industries

(011) 316 2375

P

ReMaCon Products

(011) 393 5504

R

Columbia DBL

(021) 905 1665

MPR

Reya Pele Bricks

(016) 363 0340

P

Concrete Units

(021) 386 1923

Pi

Rocla

(011) 670 7600

Pi

Conframat

0861 33 5599

P

Salberg Concrete Products

(011) 357 7600

Pi

Corobrik

(031) 560 3111

PR

Southern Pipeline Contractors

(011) 914 8500

Pi

Deranco Blocks

(041) 463 3338

MR

Shukuma Flooring System

(041) 372 1933

S

Deranco Paving

(041) 933 2755

P

Stanger Brick & Tile

(032) 457 0237

MP

Deranco Precast

(041) 463 3338

S

Stone Age Concepts

(012) 802 1496

P

Eagle Roof Tiles

(044) 874 0290

T

Technicrete

(011) 674 6900

MPRT

Echo Prestress

(011) 589 8800

S

Technicrete (Mpumalanga)

(013) 758 1203

MPRT

(00263) 448 6620

Pi

Technicrete (Mpumalanga)

(017) 689 2100

MPR

Fort Concrete Inca Concrete Products

(021) 904 1620

MP

Technicrete (Mpumalanga)

(013) 696 1153

MPR

Inca Masonry Products

(043) 745 1215

MPRT

Technicrete (Free State)

(057) 391 4200

MPR

Infraset

(011) 876 5500

Pi

Technicrete (North West)

(018) 790 4380

MPR

Infraset

(012) 652 0000

MPR

Technicrete (Limpopo)

(015) 293 8083

MPRT

Infraset

(031) 569 6900

PR

Technicrete (Gauteng)

(011) 203 7700

MPR

(00267) 392 2850

MP

Technicrete (North West)

(018) 484 6234

MPR

(021) 875 5151

R

Technicrete (E.Cape)

(041) 372 2230

MP

(00267) 393 2850

Pi

Topfloor

(021) 951 7700

S

Lategans Cement Works

(021) 873 1154

M

Vanstone Precast

(012) 541 2056

PR

Marley Roofing

(011) 316 2121

T

Vibro Bricks

(012) 374 0205

P

Marley Roofing

(013) 933 3351

T

Western Granite Bricks

(021) 904 1620

M

Marley Roofing KZN

(032) 944 4155

T

West End Cement Bricks

(011) 851 1098

P

082 324 7277

T

Kwena Concrete Products Klapmuts Concrete & Cape Retaining Kwena Rocla

Marley Roofing Cape Town

PRECAST VOLUME 6 • ISSUE 1 • 2012

CMA MEMBERS

29

ASSOCIATE MEMBERS

COMPANY NAME

TELEPHONE

ARQ Consulting Engineers

(012) 348 6668

ILIFA Africa Engineers

(016) 981 0591

J C Paving Consultant

(011) 431 0727

Pipes

(012) 644 0043

Sekhukhune and Associates

(012) 993 4776

SNA Civil & Structural Engineers

(012) 842 0000

Terraforce

(021) 465 1907

Young & Satharia Structural Civil Engineers

(031) 207 7252

CONTRACTOR MEMBERS

COMPANY NAME

TELEPHONE

Cape Wall

(021) 856 3745

Daron Construction

(034) 955 1333

Decorton Retaining Systems

(021) 875 5155

Friction Retaining Structures

(011) 608 4321

Galaxy Paving

(011) 815 1175

Kalode Construction

(011) 781 3814

Mondo Paving & Retaining Walls

(011) 708 0800

PYW Paving

(031) 763 5771

Roadstone Civil & Paving

(011) 683 7080

SA Paving Gauteng

(011) 483 1350

Vesles Civils

(012) 662 3031

Valcal International

(011) 867 2471

NON-PRODUCER MEMBERS

COMPANY NAME

TELEPHONE

Abel Equipment

(044) 874 1876

Ash Resources

(011) 886 6200

Birkenmayer H

(011) 970 3880

BASF Construction Chemicals South Africa

(011) 203 2400

C&CI

(011) 315 0300

Chryso Southern Africa

(011) 395 9700

Dick King Lab Supplies

(011) 499 9400

Kaytech

(031) 717 2300

Kobra Moulds

(003) 111 356 2460

Manitou SA

(011) 975 7770

Mapei SA

(011) 522 8476

Pan Mixers SA

(011) 397 3754

Rampf Formen GmbH

(0049) 7391 5050 148

Sika South Africa

(031) 792 6500

Soillab

(021) 988 7410

Smartstone

(011) 310 1161

Techincal Finishes

(021) 535 4455

Techmatik SA

+48 48 3690811

PRECAST VOLUME 6 • ISSUE 1 • 2012