Thermal performance and fire resistance of nanoclay modified cementitious materials

Thermal performance and fire resistance of nanoclay modified cement mortar were evaluated in this study. To prepare the modified mortar mix, part of the cement was replaced by montmorillonite nanoclay in a range of 0-2% by weight of cement. After a curing period of 28 days, the hardened mortar specimens were exposed to high temperatures of 200 °C, 400 °C, and 600 °C for 2 h. DSC and TGA tests were conducted to examine the thermal performance of the nanoclay modified specimens. The fire resistance was evaluated by comparing the residual mechanical strengths of heated specimens with the strengths of control specimens. The effect of nanoclay on the chemical composition and microstructure of heat-damaged specimens were evaluated using XRD and SEM tests, respectively. Experimental results revealed that the nanoclay modified cement mortar exhibits higher compressive, tensile, and flexural strengths than control specimens, especially at higher temperatures. The addition of nanoclay significantly reduced the degradation in the tensile and flexural strengths of cement mortar due to elevated temperatures exposure. SEM images showed that the presence of nanoclay decreased the density and the width of the hairline cracks that appeared along the cement matrix due to elevated temperature exposure.