The Optimum Amount of Waste Glass Aggregate that can Substitute Fine Aggregate in Concrete

The study that is reported in this paper was carried out to study the effects of glass sand on the properties of concrete and determine the optimum amount of waste glass aggregate that can effectively replace fine aggregate in cement concrete. The objectives of the study were to prepare concrete specimens containing various amounts of glass sand as partial replacement for fine aggregate and to determine the properties of fresh and hardened concrete specimens so produced. It was found that glass sand does not have significant effect on the workability of concrete. The density of concrete containing glass sand was slightly lower than the density of normal concrete by a factor of 1-2%. The presence of glass sand did not alter the established strength-time relation of concrete. The strength of concrete containing glass sand increased progressively with curing time. Glass sand had significant effect on the strength of concrete. A plot of concrete strength and glass sand content was a parabola curving downward. The peak strength, obtained at 10% glass sand content, was 1.2 times the target strength of 25 N/mm2. The study concluded that the optimum amount of glass sand that can effectively substitute river sand in grade C25 concrete is 16% of the proportion of fine aggregate in the concrete. For plain concrete, glass sand alone can be used as fine aggregate. It was recommended that supplementary cementitious materials should be incorporated in the concrete to suppress the deleterious alkali-silica reaction that may take place when glass concrete is exposed to moisture.