•
Due to the high fines content and viscosity, SCC concrete tends to dry
faster
than conventional concrete and therefore there is a potential of
increased
plastic shrinkage cracking, as there is little or no bleed water at the
surface. As such it is important that evaporative retarders are used
between initial screeding and finishing and curing is implemented in a
timely
manner as per specification requirements. On the
other hand the reduced
bleeding reduces the risk of plastic settlement
.•
SCC must be supplied on a continuous basis and sufficient manpower and
equipment
must be on site to avoid
any delays which may result in the concrete being left
too long without fresh concrete being applied thus creating the
potential for a
cold joint to be formed. Where concrete has been untouched
for long
periods it may be necessary to vibrate the new concrete into the old to
prevent
a cold joint from occurring.
•
In order to minimise the risk of segregation of SCC the vertical free-fall
should be limited to 3 m and the horizontal flow from point of discharge
to 6 m.
•
As SCC concretes are more susceptible to quality and material
fluctuations than
conventional vibrated concrete, a stricter
quality control regime, production
control, construction control and training regime must be put in place.
•
In concreting applications other than under water and dry bores,
consideration
should be given to undertaking
controlled field trials where all of the critical
plastic and then hardened properties can be assessed.
•
Ensure
adequate and ongoing communication between the mix
designer, the
contractor, supervising personnel and the personnel responsible for
placing SCC
concrete.
