Mechanical Properties and Chemical Characterization of Mortars with Halloysite Nanoclay after Exposure to Elevated Temperatures

Abstract

In this study, the effects of halloysite nanoclay (HNC) on cement mortars after exposure to elevated temperatures were investigated. The compressive strength, microstructure, and chemical composition of mortars with 0 %, 1 %, 2 %, and 3 % HNC were compared after exposure to temperatures of up to 1,000°C. Also, the materials analysis using diffraction program was used to analyze the X-ray powder diffraction data based on the Rietveld method. Test results revealed that the HNC samples maintained higher strength of up to 10 % at elevated temperatures when compared to plain mortars. An increase in the relative elastic modulus and a higher energy absorption rate were also observed when the HNC was added. It is safe to state that the HNC had an interlocking effect by which it obstructed the heat-induced microcracks. Furthermore, the quantitative analysis showed that the HNC lowered the calcium hydroxide amount and increased/accelerated the hydration of alite and belite in the matrix.