Effect of elevated temperature on physico-mechanical properties of metakaolin blended cement mortar

Abstract

An experimental investigation was conducted to evaluate the performance of mortars with and without Metakaolin (MK) exposed to elevated temperatures <TEX>$200^{\circ}C$</TEX>, <TEX>$400^{\circ}C$</TEX>, <TEX>$600^{\circ}C$</TEX> and <TEX>$800^{\circ}C$</TEX> for two hours. The binder to sand ratio was kept constant (1:5.23). The ordinary Portland cement (OPC) was replaced with MK at 0%, 5%, 10% 20% and 30%. All mixtures were designed to have a flow of <TEX>$94{\pm}5%$</TEX>. The compressive strength of mortars before and after exposure to elevated temperature was determined. The formation of various decomposition phases were identified using X-ray diffractometry (XRD) and differential thermal analysis (DTA). The microstructure of the mortars was examined using scanning electron microscope (SEM). Test results indicated that MK improves the compressive strength before and after exposure to elevated temperature and that the 20% cement replacement of MK is the optimum percentage.