Showing papers on "Silica fume published in 1981"

Silica reinforced rubber

Abstract: Incorporating a reinforcement promoter into the silica prior to the drying of the silica which is precipitated has been found to result in a significant improvement of the heat buildup properties of rubber reinforced by such silica as compared to adding both silica and the promoter to the rubber mixture.

Characterization and reactivity of silica fume

Abstract: : Silica fume is a fine, siliceous powder that is a by-product of producing silicon metal or ferrosilicon in a reducing environment in an electric furnace. Recent research work on cementitious materials included characterization of such a silica fume from Alabama by chemical, physical, and petrographic tests. In addition, properties of mixtures of this fume with water and calcium hydroxide were studied. Compressive strengths were determined at different ages, and the composition and microstructure of the hydrated material was studied by X-ray diffraction and by scanning electron microscopy. The results show that the silica fume is characterized by small spheres of high silica content, by very high surface area, and is almost totally amorphous. Physical tests showed that it is a pozzolan, is effective in reducing expansion due to alkali-silica reaction, and increases the sulfate resistance of mortars. Combination of this material with water and calcium hydroxide results in the formation of extremely well crystallized Type I calcium silicate hydrate (CSH-I). (Author)