The Civil Engineering Contractor June 2018 | Page 16

ON SITE
The massive piles will comprise about 40t of rebar to support the huge weight above.
The good soil that comes from the
excavations will be used on other
projects, while the rest will be
disposed of in municipal dumps.
Devan continues: “Presently, we
have completed the bulk excavation,
by and large, with one section
remaining. How we sequenced the
earthworks was by starting from the
northern face, working towards the
southern face, creating the excavation
platforms that we required for the
piling to get underway.”
The piling operations had literally
started on the day of the site visit,
with the first pile in progress.
Dan Alford, contracts manager at
Mega Pile Inland, says that Mega Pile
Inland is responsible for the major
lateral support works and piling works
within the four parking basements.
His response to comment on the
large puddles of water possibly being
14 - CEC June 2018
from groundwater seepage is: “The
significant water on the site was not
from water seepage, but from the
substantial rain experienced over the
past week,” Alford assures and adds:
“We have had about 0.5 metres of
rain since the start of the project.
Despite this, we are still on track
with meeting the deadline, although
the rain causes logistical problems
with trucks moving in and out of
the site. We were concerned about
encountering groundwater at the base
of our excavation, but fortunately, we
have not found any.”
When asked about the number of
piles, he says with a grin: “96 piles in
total. I think this was intentional, as
this is 96 Illovo.”
The piles are various diameters,
ranging from 500mm to 1.2 metres
— BIG piles, with heavy steel, to
support massive loads. The concrete
used in the piles amounts to about
700 cubic metres, with about 40 tons
of rebar.
The 13-metre-high basement’s
retaining walls are made of wet
Shotcrete, Alford explains: “Previously,
dry Shotcrete was used. This new wet
Shotcrete is an innovation; it reduces
wastage massively and also produces a
more consistent mix and wall finish.
“In the old conventional system,
using dry Shotcrete (gunite), the
process was to add the water at the
nozzle, whereas wet Shotcrete is
already mixed. By adding water at the
nozzle, the emerging concrete spray
can be inconsistent, dependent on
the consistency/pressure of the water
spray. Now we use ready-mix, which
goes straight through the nozzle. This
gives uniform quality and moisture
consistency, which also reduce
wastage considerably. Air entrainment