Effect of waste foundry sand as partial replacement of fine aggregate in bituminous concrete mixture

Abstract

Solid waste management has become one of the global environmental issues of concern. The increase in industrial activities has led to a corresponding increase in industrial by-products which are mostly disposed to landfill as waste material. This leads to the reduction of useful land and also constitute nuisance to the environment. Also, the dwindling natural resources used in construction have pushed researchers/highway communities to seek utilization of readily available waste materials and byproducts such as waste foundry sand as supplement materials in mortar, concrete and bituminous concrete mixtures. This will on the one hand reduce wastes in the environment and its effects on human health, on the other hand, it will reduce the cost of bituminous mixtures necessary for road construction as well as reduce the burden on natural resources used in the construction industry. In this study, waste foundry sand (WFS) was investigated for use as a partial replacement for fine aggregate in bituminous concrete mixtures. Physical properties test were carried out of the bituminous concrete constituent materials according to the American Society for Testing and Materials and British standard specifications and found to be satisfactory for use in bituminous concrete mix. Marshall method of mix design was used to the produced bituminous concrete at design bitumen contents of 4.5%, 5.0%, 5.5%, 6.0% and 6.5% without the incorporation of waste foundry sand (control) to determine the optimum binder content as specified by Asphalt Institute (1997), and ORN 19 (2003). An optimum binder content of 5.5% was found and consequently used to design bituminous concrete mixtures at varying percentages (5%, 10%, 15%, 20%, 25%, and 30%) replacement by weight of fine aggregate (river sand) with WFS. The results obtained show that maximum stability was attained at 30% WFS content with a value of 6.32kN and a corresponding flow of 3.1mm. Thus, from the Marshall stabilityflow test analysis, the sample prepared with 30% WFS content as a partial replacement for river sand at OBC of 5.5% satisfied the specification requirements of the Federal Ministry of Works General Specification for Roads and Bridges.