Effects of SiO2 and Al2O3 nanoparticles on the properties of borogypsum containing mortar

Abstract

This study aimed to investigate the effects of nano-SiO2 and nano-Al2O3 on the physicochemical and mechanical properties of mortars containing borogypsum. The mortars were modified by incorporating 0.2-1% nano-SiO2 and 0.5-2.5% nano-Al2O3. Various analysis methods were applied to the nano-modified samples to observe changes in the fresh and hardened features of the mortars. The results showed that the nanoparticles used could not promote the setting of the mortars. The highest compressive strength of 67 MPa was achieved when 1% nano-Al2O3 was used. Adding 0.4% nano-SiO2 resulted in the highest flexural strength of 9.13 MPa. Supporting the water absorption test, SEM and BET morphologic analyses showed that nano-SiO2 was more effective in developing a denser microstructure than nano-Al2O3. The findings of the thermal analysis suggest that substituting nanoparticles in borogypsum-containing mortars could not decrease the unreacted CH ratio during the hydration under the studied conditions.