Strength Characteristics of Rice Husk and Corn Cob Ash Blended Cement Concrete

The study investigates the mechanical properties of concrete incorporating Rice husk Ash (RHA) and Concorb Ash (CCA) as cementitious binders. Concrete cubes was prepared from a standardized prescribed mix of 1:2:4. The cement component in the reference mix was replaced with combined % weight of rice husk ash and corncob ash. The physical and chemical composition of RHA and CCA were examined as well as the workability and compressive strength properties of varying percentage of RHA and CCA blended cement concrete. Water–cement ratios of 0.6, was adopted for the reference and blended mixes. A total of 75 concrete cubes of different percentages by weight of combination of RHA and CCA to Portland cement in the order of 0%, 10%, 20%, 30%, and 40% were cast. The strength measurements of concrete were performed at the ages of 7, 14, 21, 28 and 56 days. The results revealed that compressive strength increased with increase in curing age but decreased as the RHA and CCA contents increased. The compressive strength of concrete cubes with the combination of RHA and CCA was lower at early stages but improves significantly up to 56 days. The highest compressive strength was 22.94N/mm2 and 26.27N/mm2 at 56 days for 0% and 10% combination of RHA and CCA respectivelyBased on the test results the study concluded that 10% RHA and CCA content is adequate as supplementary cementitious material for blended concrete.