Title: Roles of Silica Fume, Slag, and Fly Ash in the Development of High-Performance Concrete Microstructure

Author(s): S. L. Sarkar

Publication: Symposium Paper

Volume: 149

Issue:

Appears on pages(s): 449-460

Keywords: admixtures; aggregates; calcium oxides; C-S-H; fly ash; high-performance concretes; hydration; microstructure; pastes; silica fume; slags; Materials Research

DOI: 10.14359/4093

Date: 10/1/1994

Abstract:
The combined use of chemical and mineral admixtures has resulted in a new generation of concrete called high-performance concrete (HPC). Understanding the roles of mineral admixtures, such as silica fume, fly ash, and slag depends on in-depth microstructural investigation of HPC at different ages. What is of major interest concerning these materials is their contrasting hydraulic behavior. Whereas silica fume and fly ash are pozzolanic, slag is strictly cementitious. The early strength of concrete increases when silica fume is incorporated, but the activity of slag and fly ash starts much later, and therefore, manifestation of changes in concrete properties, such as strength enhancement, also appears to be delayed. It is in this light that the roles of these admixtures, both individually and in combination, are described in terms of the development of HPC moisture.