Performance of Rice Husk Ash - Calcium Carbide Waste in Concrete

This paper examines and present the findings of the physical and mechanical properties of concrete containing rice husk ash (RHA), and the blend of rice husk ash with calcium carbide waste (RHA-CCW). Concrete cubes, cylindrical and beam specimens containing different percentages of RHA and RHA-CCW by weight of cement (5, 10, 15 and 20 %) were cast. Compressive strength test was carried out after the specimens were cured in water for 7, 14, 28 and 56 days. Test for tensile and flexural strength was carried out after 28 days curing. Initial and final setting time test was carried out on mortar specimens with the same percentage of RHA and RHA-CCW. Bogues model was used to determine the elemental and compound composition of cement when blended with the RHA and RHA-CCW. From the results obtained, the compressive strength of RHA-CCW concrete increases as cement is partially replaced with RHA-CCW content, with the maximum strength attained at 5 % replacement. RHA concrete attains it maximum strength at 10 % replacement. The maximum compressive strength results obtained for both RHA and RHA-CCW concrete were higher than the strength of plain concrete (0 % replacement) by 1.1 % and 14.7 % respectively. Interestingly, results obtained for the tensile strength also shows a similar pattern of strength development with that of compressive strength. The flexural strength properties of concrete was improved upon when RHA-CCW was used in concrete compared to RHA. The results of setting time test for RHA mortar showed a decrease in setting time, while the reverse was the case for RHA-CCW mortar. In conclusion, provided adequate curing is maintained, the used of RHA-CCW gives a better performance in concrete than RHA. However, they both perform better in concrete than the plain, and can be used as additives in concrete production.