Data for: Effect of elevated temperatures on strength and microstructure of mortar containing nano-calcined montmorillonite clay
The fire resistance of cement-based composite mortars is highly dependent on their mechanical, chemical, and thermal characteristics. This study presents the results of an experimental investigation on the mechanical properties and microstructure of nano-calcined montmorillonite clay (NCMC) cement mortars at high temperatures. The NCMC was prepared via thermal activation of nano-clay, and the produced mortars with progressive NCMC replacements were subjected to temperatures of up to 900 °C. The fire-resistance properties of the produced mortars and their role were analysed through thermo gravimetric analysis, X-ray diffraction, and scanning electron microscopy. Both the residual compressive and flexural strengths of mortars containing NCMC improved after the addition of NCMC. However, the residual compressive strength was enhanced more than the flexural strength, owing to the higher sensitivity of the former to microcracks emerging at elevated temperatures. Microstructural results revealed that the use of thermally treated NCMC having a high surface area and aspect ratio reduced the density and width of microcracks, reduced CH to further produce CSH gel, and strengthened the matrix; these findings explain the higher residual mechanical strengths of the thermally treated NCMC mortars. Furthermore, the mass-loss behaviour improved. The optimum NCMC replacement was determined to be 3% by weight.