Precipitated silica, fumed silica, and gel silica are purposely made forms
of silica. While these materials are amorphous and would be expected to
perform well in concrete, they are typically too expensive for such use.
More information on these materials may be found in ASTM E 1156 or in the
work of Dunnom.
Colloidal silica is a stable dispersion of discrete synthetic amorphous
particles of silicon dioxide. Colloidal silica may also be referred to as
silica gel. Again because of the expense, colloidal silica is not being
used in concrete.
Silica flour is a crystalline form of silica that may perform as a filler
material in concrete. It will not contribute as a pozzolan.
ASTM E 1156, Standard Practice for Health Requirements for Occupational
Exposure to Synthetic Amorphous Silica.
Dunnom, D., ed., 1984, Definitions for Asbestos and other Health-Related
Silicates, STP 834, ASTM, West Conshohocken, PA.
The Silica Fume Association
38860 Sierra Lane, Lovettsville, VA 20180
Tel: 540.257.4224 Fax: 540.822.9456
