The Civil Engineering Contractor March 2018 | Page 27

TECHNOLOGY
Working on multiple projects simultaneously,
their work is repetitive in nature and they do
not have to contend with the many variables
that are encountered on site. This has also
played a prominent role in the high levels of
accuracy and quality that have been achieved
on many HCC projects, while also contributing
towards their buildability.
Different techniques are deployed in
the manufacture of precast concrete items.
They vary from steel fixing and
placing concrete in conventional
moulds, through to extrusion that
entails mechanically placing the
construction material on a long pre-
stressing line.
Both manufacturing techniques
are undertaken at ground level
and do not require temporary
support work and scaffolding, as is
the case on a conventional in situ
building programme. In addition to
providing safer working conditions,
this approach promotes higher
productivity levels, with fully cured
precast concrete elements able to be
manufactured in as little as 24 hours
from the placement of the steel
reinforcement in the moulds.
In situ construction conventionally
requires three separate teams.
Following on the earthworks,
workers place and fix the steel
reinforcement for the foundations
while another team then establishes
the formwork. These teams,
comprising mainly moderately
skilled people, may be required to
work in awkward positions and at
heights, compounding safety risks on
construction projects.
The placement and finishing of
the concrete is then undertaken
by a combination of skilled and
unskilled workers.
Depending on the type of elements
being used, a team comprising only
about seven people is required to
install a precast modular system. It
includes a specialist mobile crane
operator who can safely handle
the lifting and placement of the
heavy precast concrete elements
as they arrive on site. In addition
to timely transportation of the
items from the factory to the site,
rigging capabilities are critical for
a successful HCC project. Not only
do professional teams demand high
levels of efficiencies, they want
to be reassured that the handling
of the heavy items will be
undertaken safely.
One of Corestruc’s strengths
has always been its own in-depth
expertise and capabilities in
all components of the precast
concrete supply chain, starting
with design through to full
project management during the
installation phases. Its teams work
alongside those tasked with the in
situ component of the project.
The crane operator is accompanied
by a rigger. The number of workers
accompanying the crane operator
and rigger depend on the type of
project, and they work at heights
with man-access platforms, as
opposed to scaffolding.
Precision in the casting process and
sound upfront planning also mitigate
inaccuracies and over-handling of the
various precast concrete elements.
The role that precast concrete
plays in providing a cleaner site is
noticeable, minimising the need for
heavy construction materia l delivery
vehicles. This also contributes
towards safer site practices.
It has taken time for HCC
projects to gain traction in South
Africa, compared to countries
in the developed world. This is
considering the focus on labour-
based construction in the country.
The extremely labour-intensive
nature of the manufacturing
component of the precast concrete
value chain is often overlooked.
In addition to providing a safer
working environment for many
people, workers in the precast
concrete sector also enjoy secure
employment, motivating ongoing
investment by companies into
internal skills development and
training of their staff. This, in turn,
has resulted in higher paid jobs
and, therefore, improved living
conditions. nn
Willie de Jager is the
managing
director
of
Corestruc. He is a civil
engineer specialising in precast
concrete structures. De Jager’s
expertise in the field includes
project management during
the installation phases of the
precast concrete structure.
CEC March 2018 - 25