Title: Study of Concrete Containing Silica Fume and Activated Amorphous Silica

Author(s): H. Tanaka

Publication: Symposium Paper

Volume: 145

Issue:

Appears on pages(s): 901-916

Keywords: compressive strength; concretes; permeability; silica; silica fume; water; Materials Research

DOI: 10.14359/4419

Date: 5/1/1994

Abstract:
The physical properties of concrete with additions of silica fume and activated natural amorphous silica were investigated. Much research has been carried out to this point regarding the effects of silica fume on concrete, and it has been made clear that silica fume additions are effective in improving strength characteristics, resistance to water permeation, etc. In the present study, the effect of addition of a mix of silica fume and activated natural silica on the properties of concrete was investigated. The naturally occurring amorphous silica was activated by first treating it with alkali, after which it was neutralized by acid treatment. It was found that addition of this activated amorphous silica and silica fume is effective in reducing the water permeability of concrete to a significant extent. The amount of silica fume required in this case is less than a third of what is normally used in silica fume concrete. SEM observations suggest that the decrease in water permeability is due to a denser structure being obtained because of the uniform distribution of the activated amorphous silica and silica fume particles within the concrete and the effective filling up of the interparticle spaces by calcium silicate gel.