Investigation on Suitability of GHA – RHA as Partial Replacement of Cement in Concrete

This paper presents the studies conducted to know the strength characteristics of cement concrete made with Ordinary Portland Cement (OPC) and two agro wastes i.e. Rice Husk Ash (RHA) with Groundnut Husk Ash (GHA). GRA Cubes were casted with different percentage level of replacement with both ashes such as 0%, 2.5%, 5%, 7.5%, 10% and 12.5%. The Chemical analysis was done to know pozzolana properties of GHA and RHA. It was found that slump and density decreases were decreases as the amount of ashes increases in control mix concrete. Slump for control mix and 10% replacement was found to be 70 mm and 50 mm respectively. Density for control mix and 10% replacement was found to be 2440 kg/m³ to 2280 kg/m³ respectively. Compressive strength also decreases with respect to control mix except for 10% replacement with 27.51 N/mm² and 27.01 N/mm² respectively. Scanning Electron Microscopy (SEM) and Chemical analysis in micro areas and Energy Dispersive X–ray Spectrometry (EDS) analysis was also done to analyse the phase changes and microstructure of mature concrete. It was found from the observations that 10% replacement of cement with GHA – RHA is suitable in concrete for construction of lightweight & non – load bearing structures.