EFFECT OF CHEMICALS ON THE COMPRESSIVE STRENGTH OF RICE HUSK ASH CONCRETE

Abstract

This paper is an empirical investigation on the effect of chemicals on the compressive strength of Rice Husk Ash (RHA) concrete. This was achieved by partially replacing Ordinary Portland Cement (OPC) with 10 percent (%) of RHA to produce concrete cube samples. Samples of 100% OPC concrete were equally produced and served as the control. The quantities of cement, fine aggregate and coarse aggregate used for the research were obtained through absolute volume method of calculation having a mix ratio 1: 2: 4. Water-cement (w/c) ratio of 0.6 was adopted for the control specimen and 0.65 for the specimen with RHA. Twenty one (21) concrete cubes were produced for each specimen. The specimens (OPC/RHA, and the control) were completely immersed in ordinary water for 28 days curing periods. The cured specimens were thereafter, completely immersed in chemical solution of 5% H2SO4 , 10% MgSO4 and ordinary water for another 28 and 56 days. The percentage reduction in strengths of OPC/RHA and the control specimens in 10% MgSO4 at 56 days were observed to be 2.09% and 10.06% respectively. In 5% H2SO4, the percentage reductions in strengths of OPC/RHA and the control at 56 days were also observed to be 25.13% and 33.61% respectively. The results show that RHA concrete exhibits better strength than 100% OPC concrete in MgSO4 solution. The two specimens tested in H2SO4 performed poorly at 56 days. The study concluded that OPC/RHA concrete proved resistant to MgSO4 and can be recommended as sulphate resistant additive in concrete production.