Studies on Effect of Silica Fume on Workability and Strength of Concrete

Abstract

Silica fume is an industrial by product during the production of silicon metal or silicon alloys. Silica fume is known to improve the mechanical characteristics of concrete. The principle physical effect of silica fume in concrete is that of filler, because of its fineness can fit into space between cement grains in the same way that sand fills between particles of coarse aggregates and cement grains fill the space between sand grains. As for chemical reaction of silica fume, because of high surface area and high content of amorphous silica in silica fume, this highly active pozzolans reacts more quickly than ordinary pozzolans. The use of silica fume in concrete has engineering potential and economic advantage. This paper presents the optimal percentage of silica fume from the results of an experimental investigations carried out to for sustainable and economical production of concrete. It is observed that the optimum dose of silica fume is 15% (by weight), when used as part replacement of OPC. The silica fume inclusion decreases the workability and increases the strength of concrete considerably.