ENATO EFOSA

This work investigated the possibility of using waste concrete materials as partial replacement for coarse aggregates in concrete work and some of the properties of Recycled concrete aggregates. The Recycled concrete aggregate used was gotten from waste samples in the laboratory of the Department of Civil/Structural Engineering of the University of Benin. These samples were dried and crushed, they were used to replace Natural Coarse Aggregate under different percentage of 0%, 20%, 40%, 60%. The test done was Aggregate Impact Value (AIV), Sieve Analysis, Slump Test, Compressive Strength and Split Tensile Strength Test. With a total of 36 cubes and 36 cylinder made, curing age of 7, 14 and 28 days were used to investigate the strength of the concrete made. The results obtained show that the aggregate impact value of Natural coarse Aggregate was 27.43% and that of Recycled concrete Aggregate 35%. Slump value for 0%, 20%, 40%,60% are 40.50, 30.50, 30.30, 30.70mm. The compressive strength test of 0% is 23.30N/mm2 at 28 days, 20% is 28.11 N/mm 2 at 28 days, 40% is 20.10N/mm2 at 28 days, 60% is 26.96 N/mm2 at 28 days, and the split tensile strength of 0% is 2.69 N/mm2 at 28 days, 20% is 2.75 N/mm2 at 28 days, 40% is 1.78 N/mm2 at 28 days, 60% is 2.18 N/mm2 at 28 days. It was seen that Recycled concrete aggregate (RCA) decreases with increase in percentage of replacement and the maximum or optimum strength was obtained at 20% replacement.