Effect of Foundry Sand and Mineral Admixtures on Mechanical Properties of Concrete

Foundry sand waste can be utilized for the preparation of concrete as a partial replacement of sand. The strength properties of M25 grade concrete are studied with different percentages of replacement of fine aggregates by foundry sand at 0%, 10%, 20%, 30%, 40%, and 50%. The optimum percentage of foundry sand replacement in the concrete corresponding to maximum strength will be identified. Keeping this optimum percentage of foundry sand replacement as a constant, a cement replacement study with mineral admixtures such as silica fume (5%, 7.5%, 10%) and fly ash (10%, 15%, 20%,) is carried out separately. The maximum increase in strength properties as compared to conventional concrete was achieved at 40% foundry sand replacement. Test results indicated that a 40% replacement of foundry sand with silica fume showed better performance than that of fly ash. The maximum increase in strengths was observed in a mix consisting of 40% foundry sand and 10% silica fume. SEM analysis of the concrete specimens also reveals that a mix with 40% foundry sand and 10% silica fume obtained the highest strength properties compared to all other mixes due to the creation of more C-H-S gel formations and fewer pores.