The Civil Engineering Contractor March 2019 | Page 24

ON SITE
ended with the floor of the structure.
The roof structure, comprising
precast-concrete columns, beams,
and hollow-core slabs, was built by
Corestruc in only four days.
Mbako Projects & Trading then
proceeded with the construction of
the 2.5km pipeline and chambers, as
well as the ring beam of the structure,
while CoreSlab manufactured
the walls in a controlled factory
environment. The precast-concrete
factory is the heart of the project.
It is a labour-intensive undertaking
where many skilled people work on
multiple projects simultaneously in a
controlled and safe setting.
“These factories rely extensively
on a high level of skills, so these
operations tend to place immense
emphasis on training and staff
retention to ensure a high quality of the
concrete elements. In so doing, they
are creating long-term employment
in the construction sector, which is
in line with government policies,”
Holtzhausen says.
Meanwhile, ancillary work,
counting the pipeline, provided
ample employment opportunity
for members of surrounding
communities, as well as local
emerging contractors in line with
“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.”
a typical Expanded Public Works
Project that is financed by the
Municipal Infrastructure Grant.
Willie de Jager, managing director
of Corestruc, says that he is proud to
be involved with a municipality that
has taken a proactive approach to
service delivery, while demonstrating
its willingness to test state-of-the-
art technology that will assist in
accelerating service delivery.
Speed of delivery
The benefit of constructing a precast
reservoir is that multiple tasks can be
performed relatively simultaneously,
which is not possible with the
conventional manner. The roof,
floor, and walls of a reservoir cannot
typically be done simultaneously —
at the most, two can, but De Jager
explains that when using precast-
concrete slabs, all three tasks can
overlap. This particular project
commenced at the beginning of
December 2018 and was due for
completion end-January or the
beginning of February.
Site manager Casten Kunaka of
Mbako describes the precast method
as “pretty fast”, because in normal
circumstances, “If we were going to
do the walls with the traditional in
situ concrete, we couldn’t have started
with the walls before we finished with
the floors — but we can now do
it uninterrupted because there is no
formwork cluttering up inside. It’s a
clean site — it makes a big difference.”
This process also mitigates the
need to coordinate the delivery of
construction materials to site. Already
having the structure of a roof in place
also enables the floor concrete to cure
under the best possible conditions.
De Jager says the walls alone were
constructed in just eight working
days, in comparison to four to six
months using the conventional
method — the difference being that
all that work now takes place off-site
in the factory. “It is this factor which
The precast methodology enables all components of the reservoir to proceed simultaneously.
22 | CEC March 2019
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