Preliminary Study of Lime-Pozzolan Based Cement after Exposed to High Temperatures

Abstract

This paper presents a preliminary study on the properties of lime-pozzolan based cement and the effect of high temperatures on these properties. Conventional lime-pozzolan cements (LPC), alkali-activated LPC and hybrid alkali-activated LPC pastes were experimentally investigated. Microstructural analyses were performed based on XRD and SEM tests to identify the hydration products. Based on the results, the strength improvement of hybrid alkali-activated LPC cement, where ordinary Portland cement (OPC) was used to enhance the early age strength, could be due to (i) the dissolution of Ca(OH)2 in the mixtures, and (ii) the pozzolanic effect of pozzolanic materials, which interacted with the free Ca(OH)2 during hydration. The residual strength results indicated that the materials lost the strength gradually when exposed to the temperature up to 400°C, except for hybrid cement which showed a slight increase in strength. The microstructure analysis results indicated that the deterioration of the materials was due to the decomposition of hydration products at high temperature.