Structural, Mechanical and Thermal Properties of Cement Effect of Fractional Addition of Rice Husk Ash

Abstract

It has been established that Rice Husk Ash (RHA) contains a large amount of Silica and causes environmental problems if left to burn. An inevitable and preliminary interest of the current work was to investigate the effect of partial replacement of RHA in ordinary Portland cement (OPC) regarding variation in its compressive strength, thermal conductivity and structural properties. The RHA was obtained via controlled burning followed by grinding and replacement with OPC. RHA has been added at various percentages from 10 to 50% with an incremental step size of 10%. The properties of the final product have been investigated after preservation of the samples for 3, 7, 14, 21, 28, 56, and 90 days. The study reveals that samples containing 10% of RHA exhibit maximum compressive strength of 2066.33 Psi with a density of 2.65g/cm3 when cured for 28 days. Due to high relative humidity and temperature after 28 days the strength was slightly lower than the specimen preserved in water. The thermal conductivity measurements revealed that samples with 50% of RHA exhibit minimum thermal conductivity as 0.81 Btu/ft2/hr/0F while maximum thermal conductivity was obtained at 10% RHA replacement. XRD analysis showed a significant transformation in the phase and crystallinity of the mixture. The average crystallite size of pure RHA was 2227.69 Å, however, for the mixture, the crystallite size was observed to be 712.2 and 162.77 Å with 10 and 40 % of the RHA, respectively. This study concluded that partial replacement of RHA in OPC provides a low-cost and insulating building material for the construction industry.