The document discusses the utilization of foundry waste sand in the preparation of concrete. It presents the results of experiments conducted to study the compressive strength, split tensile strength, and flexural strength of M20 and M25 grade concrete containing 0%, 10%, and 100% replacement of foundry waste sand in place of fine aggregate. The tests were conducted at curing periods of 7, 28, and 56 days. The results showed that 100% replacement of foundry waste sand can be used for M20 and M25 grade concrete based on the compressive strengths achieved at different curing periods being comparable to control mixes. Flexural and split tensile strengths were also found to be comparable between control mixes and mixes with foundry