Physical and Thermal Properties of Rice Husk Ash Blended High Strength Concrete at Elevated Temperature

Abstract

High temperature is one of the most detrimental effects that cause important changes in concrete's physical, thermal and mechanical properties. Despite numerous advantages accrued to High Strength Concrete (HSC), it may experience damages such as cracks and spallings as in the case of Normal Strength Concrete (NSC). The addition of pozzolan such as Rice Husk Ash (RHA) as partial replacement of cement in concrete is a well known method for improving the strength and durability of NSCs because of the interface reinforcement. In this study, RHA as a partial replacement material in HSC at high temperature to prevent spallings and improve thermal and physical properties were investigated. The Ordinary Portland cement (OPC) was partially replaced by 0%, 5%, 10%, 15%, and 20% to produce grade 50N/mm2 concrete cube and disc samples. Concrete was first made without supplementary cementitious material, which served as the control, concrete. The cubes and disc were cured for 28, 56 and 90 days and the hardened concrete was thermally treated at 250C (control), 2000C, 4000C, 6000C and 10000C for 2hours. The physical properties, such as cracks/ spalling, weight, and thermal properties such as thermal conductivity, specific heat and thermal diffusivity and mass loss were conducted on the hardened samples and compared with the control. The results showed that the addition of 5% RHA in OPC led to improvement in physical and thermal properties of the concrete when exposed to elevated temperature up to 400°C.