Environmental Enhancement through Utilization of Silica Fume as a Partial Replacement of Fine Aggregate in Concrete

Abstract

The proper disposal of silica fume, an industrial by product waste, is one of the major issues for environmentalists world wide since dumping of silica fume as a waste material may cause severe environmental problems and hazards. An experimental research program was carried out to study the utilization of silica fume in concrete instead of dumping it as a waste material. Fine aggregate was partially replaced with 5, 10, and 15% of silica fume by weight. Compressive strength of concrete specimens, at three water/cement ratios of 0.50, 0.55, and 0.60, were compared with concrete specimens, with no silica fume, at 7, 28, and 56 days age. Specimens were cast and tested in accordance to ASTM standards. Test results indicated improvement, of up to 21.6%, in the compressive strength properties of concrete by the inclusion of silica fume as a partial replacement of fine aggregate. Compressive strength of concrete containing 10 to 15% silica fume was acceptable for structural applications since the minimum compressive strength was more than 27 MPa at 28 days. Environmentally speaking, results suggest that silica fume, used as a partial replacement of fine aggregate, could be conveniently used in concrete industry as a means of waste product utilization and as a saving of fine aggregate resources.

 Keywords: Concrete, Silica fume, Compressive strength, Fine aggregate, environmental hazards, Waste utilization