THE USED OF PARTIAL REPLACEMENT OF CEMENT WITH CORN-COB ASH IN A CONCRETE PRODUCT

Abstract: This study concerns the investigation of concrete produced by partial replacement of cement with corn cob ash (CCA). Corn cob ash was obtained and used to replace cement partially in specified ratios of 5%, 10%, 15%, 20% and 25%. Concrete cubes were casted and cured in ages base on curing life was provided of 7, 14 and 28 days respectively. While concrete beams were cast and cured for 28 days. Compressive strength test was carried out on the cubes and the flexural strength on beam. The results showed that the concrete strength decreased with increasing replacement with the corn cob ash (CCA). The 28 days compressive strength for 5% replacement was 28.78N/mm2 , 10% replacement was 26.22N/mm2 , 15 % replacement was 22.33N/mm2 , 20% replacement was 20.27N/mm2 and 25% replacement was 17.33N/mm2 respectively while its flexural strength for same age for 5% replacement was 9.98N/mm2 , 10% replacement was 8.58N/mm2 , 15% replacement was 7.82N/mm2 , 20% replacement was 6.56N/mm2 and 25% replacement was 5.72N/mm2 . The initial and final setting time of OPC-CCA at 10% replacement was observed to be 168minutes and 305minutes respectively. The density of OPC-CCA was also observed to decrease with increasing CCA replacement. The 28 day density for 10% CCA replacement for concrete cube was 2373.33kg/m3 and that of rectangular concrete beam was 2575kg/m3 . The specific gravity of CCA was 2.55. It was concluded that CCA can be used as partial replacement for cement in concrete production as well as for walls of building units and other mild construction works, and replacement should not exceed 10% as strength produced above this replacement level may not be adequate for strength requirements. Key Words: Cement, Corn Cob Ash, compressive strength, specific gravity, Partial Replacement.