As noted earlier, silica-fume concrete usually does not bleed. While the
lack of bleeding is certainly a benefit for strength and durability, it does
make the concrete more susceptible to plastic shrinkage cracking. The keys
to overcoming the tendency for plastic shrinkage cracking are to understand
the phenomenon and to be prepared ahead of the placement to take the
necessary preventative steps.
The potential for plastic shrinkage cracking in silica-fume concrete will
increase with lower water-cementitious materials ratios and with increasing
amounts of silica fume in the concrete.
A more detailed discussion of plastic shrinkage cracking and preventative
measures may be found in ACI 305R-91, "Hot Weather Concreting" and in ACI
308-92, "Standard Practice for Curing Concrete."
The Silica Fume Association
38860 Sierra Lane, Lovettsville, VA 20180
Tel: 540.257.4224 Fax: 540.822.9456
