The Civil Engineering Contractor March 2019 | Page 26

ON SITE
previous project, so we changed the
design to position them differently —
and now it works perfectly.
“We do the same thing over and over,
so our intellectual capital is constantly
developing through repetition,
enabling us to learn and invest in our
technology.” The company also does
stadiums, bridge beams, and parapets,
in addition to structures, namely
retail, industrial, and commercial
buildings, and bespoke projects.
Where the possibility exists for
things to go wrong, says De Jager, is
in the accuracy of the factory casting.
“Ten panels are manufactured at a
time. Each panel has its own drawing
and its own quality process and
quality documentation recording pre-
inspections, post-inspections, and
concrete strength (70–80Mpa). The way
we achieve these accuracies is by having
control of the whole process, and it was
for this reason that we opened our own
engineering shop, which enabled us to
manufacture and cast-in components
that we intended while designing the
shutters ourselves. Without that total
control of the process, something
somewhere would likely be missed and
then the total installation would not
work. It is this total control that speeds
up the process.”
While the walls were still being
installed, the centrepiece of the
roof was constructed and the first
panels for the perimeter of the roof
delivered. These have a 10.8m span
and are 250mm thick. The panels are
installed without the use of props
— except the first — which would
encumber the space other workers
need. When the first panel of the
wall is set with external props, each
subsequent panel is set against the
previous one. “An important aspect
of the design is an understanding of
how the different trades all work, so
our process does not obstruct any
of them,” says Meyer van Rooyen,
Corestruc’s project manager.
A concrete pump on site is
required to be highly variable, as
the nature of the project means that
24 | CEC March 2019
Willie de Jager, managing director of Corestruc (left), with Rudi Bezuidenhout of Mbako
Projects & Trading.
small quantities of concrete are often
required (as little as 5m 3 /hour),
increasing sometimes to 30m 3 /hour.
One particular problem of the site,
which slowed the project, was the
shortage of aggregate, says Kunaka,
as there were no suitable quarries or
borrow pits in the area. “We initially
had access to suitable material from a
local borrow pit near Kwaggafontein,
but the quality subsequently
deteriorated during construction.
We had already finished with the
earthworks, and because conditions
were wet, we initially could not
identify changes in the material. But
once we finished with compactions
and it was dry, the concrete started
to crack and that is when we realised
the material was unsuitable. We had
to rip out the whole floor platform
and bring in new material. We
required G6, but the borrow pit
had downgraded to G7 and G8. In
particular, the clay content was too
high. We ended up using commercial
material after testing all the borrow
pits around here but couldn’t get the
proper material.”
The ‘mother’ ship
The view from Mathysenloop is hilly
and scenic, with numerous reservoirs
visible on surrounding hills — some
part of the broader programme,
though not of this particular project,
the reservoir at the centre of which
is the ‘mother’ that feeds them by
pumps. Currently, many of the
existing reservoirs are fed by borehole
water, which is insufficient.
Bezuidenhout explains some of
the surrounding work: “A 13km
pipeline stretches from Bundu
to Boekenhouthoek and on to
Mathysenloop, where there is a
chamber which has an outlet pipe
into the reservoir for storage.”
The trench for the long pipeline is
dug by excavator down to the rock
foundation, at which level drilling
and blasting is used to get the level
down a further 1.5m to 1.8m. “It
must be placed at a certain depth
because the pressure on this pipe is
enormous,” says Bezuidenhout.
He explains that the major
challenge of the project is the rural
nature of the location, which is typical
and expected — and there is none of
the politically motivated stoppages
that affect so many other projects in
South Africa. Bezuidenhout explains
that local communities have been well
involved in the work and supportive,
with 30% of the contract work
having been allocated to community
contractors. “They bid for the work
and we selected the best ones. They
were involved with digging the
trenches, the drilling, and the blasting
and they were good.” nn
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