P. K. Mehta describes the transition zone in his textbook, Concrete:
Structure, Properties, and Materials.
ACI Committee 234 describes the role of silica fume in the transition zone
in the committee document, ACI 234R-96, Guide to the Use of Silica Fume in
Concrete.
The Silica Fume Association
38860 Sierra Lane, Lovettsville, VA 20180
Tel: 540.257.4224 Fax: 540.822.9456