The effect of rice husk ash properties on the strength and durability of concrete at high replacement ratio

The objective of the study is to investigate the mechanical properties of Rice Husk Ash with different replacement levels on the strength and durability of concrete. Three types of rice husk ash (A, B and C) with differences in chemical composition and physical properties were used. Ordinary Portland Cement (OPC) type 52.5 N was replaced with 5%, 10%, 15%, 20%, 30%, 40% and 50% RHA (by weight) keeping the ratio of the water/cementitious material at a constant value of 0.50. Superplasticizer was used to maintain the workability of the fresh concrete within acceptable values. The compressive strength was measured after 7, 28 and 90 days, while splitting tensile strength was obtained at age of 28 and 90 days. Migration coefficient of chloride ion penetration was evaluated using non-steady-state migration tests [1] at 28 days age. The results revealed that the RHA properties (silica form, fineness, silica percentage and loss on ignition) have a direct impact on the development of strength at long-term age [2]. Experiments showed that even with 50% replacement of OPC with RHA, concrete has a higher strength and durability performance compare to OPC concrete. According to the results, increasing replacement ratios leads to decreasing porosity and in turn increasing strength and durability of concrete.