Mixing in a laboratory mixer may not be vigorous enough to break up all of
the silica-fume agglomerations in the densified form of the product. Either
use undensified silica fume or batch densified silica fume with the coarse
aggregate and mix for several minutes before adding the remainder of the
ingredients.
Depending upon silica-fume content and water-cementitious materials ratio,
there may be no measurable slump before the chemical admixtures are added.
It may be appropriate to add a WRA early in the mixing process and a HRWRA
after the cementitious materials are wetted.
The Silica Fume Association
38860 Sierra Lane, Lovettsville, VA 20180
Tel: 540.257.4224 Fax: 540.822.9456
