August 2013
CONSTRUCTION WORLD
62
A successful product is one that gets used more
than once, having satisfied the expectation of
the client. Below is a showcase of a Terraforce
noise barrier retaining wall that used the same
local retaining block to a extend long-standing
retaining walls.
precast concrete products
KNOWN AS THE CITY OF
Tshwane’s
Shovagakula (Easy) Paving Project, it is
being run over three years in several
phases and aims to encourage the use
of bicycles in the place of cars for travel
within Olievenhoutbosch.
Phase I, which was begun in April and
completed by the middle of June, involved
the construction of pavements 2,2 m wide
1 600 m long using 50 mm bevelled pavers
as well as Figure 10 and 12 concrete kerbing
supplied by ConcreteManufacturers Associa-
tion (CMA), member MVA Bricks.
Construction involved compacting in-situ
material to 90-93%, adding and compacting a
150 mm layer of G5 mixed with four percent
of cement, and topping that with 20 mm of
river sand. Once the pavers were laid, they
were covered with plaster sand to fill the
joints between the pavers. The surface was
then swept and compacted to form a very
attractive and hard-wearing surface.
The terracotta coloured pavements were
edged with a header course of charcoal pav-
ers whichwere also used for decoration strips
at every five metres.
The main contractor on Phase I was MK
Brick and Earthworks, owned and run by
Nathaniel Kgobe.
Kgobe says that 35 peoplewere deployed
for the execution of Phase I, 28 of whomwere
unskilled members of the local community.
“We trained them in all aspects of CBP
surfacing including the preparation of the
sub-base, the actual laying of pavers and
the installation of kerbing, and they have
acquired skills which they can use on other
projects of this nature,”said Kgobe.
●
Noise barrier wall extension
The wall, approved by Harries Projects, is a long wavy sound
barrier along Ratanga Road that shields residents of the Oa-
sis Retirement Centre from excessive noise and prying eyes.
The steep road-facing wall was designed with three curving ter-
races to reduce the overall footprint of the 500 m earth berm and
to improve overall noise absorption.
Growing a vintage wall into the future
The retaining wall, installed in 2006 by Cape Town based Terraforce
approved contractor, DecortonRetaining Systems, consists of around
8 000Terraforce L12 Rock Face blocks with a concrete foundation for
each terrace. A subsoil drainage system is located behind the bottom
row of blocks while the earth backfill is reinforced with Polytex 115
geo fabric every third row of blocks. The three meandering terrace
walls each reach a maximum height of 1,8 m to create terraces of
varying width.
Seven years later thewall is completely covered by (mostly) water
wise, indigenous plants that are also effective in preventing wind
erosion on the gently sloping embankments that face the buildings.
Pleased with the way the wall has been performing, Harries Projects
approved an extension of the noise barrier by around 13 000 blocks,
as the development keeps growing. Constructionwas completed by
Decorton in December last year.
●
LEFT:
The new section of the noise barrier wall.
RIGHT:
The old section as it looks today.
CBP used in paving project
Precast concrete block pavers
(CBP) and kerbing have been
used to construct safe, attractive
and durable pavements in
Olievenhoutbosch Ext 36, for
both pedestrians and cyclists.
LEFT:
Newly laid pavers at The City of
Tshwane’s Shovagakula (Easy) Paving
Project in Olievenhoutbosch Ext 36.
A header course of charcoal pavers being
laid in Olievenhoutbosch Ext 36.
MVA Brick’s Figure 12 kerbing is installed prior
to the construction of CBP pavements.
