Enhanced mechanical and photocatalytic performance of cement mortar reinforced by nano-TiO2 hydrosol-coated sand

This study investigated the impact of natural sand supported nano-TiO2 hydrosol (TiO2@Sand) on the mechanical and photocatalytic performance of cement mortar and the underlying mechanisms. The incorporation of TiO2@Sand in cement mortar (TiO2 was 0.6 wt% of cement) improved 28-day compressive strength by 67% compared with the one without nano-TiO2. Various beneficial changes towards improved mechanical strength were also observed in TiO2@Sand cement mortar: reduced total porosity by 35%, densified interfacial transition zone (ITZ) microstructure, enhanced modulus of ITZ by 54%, reduced ITZ thickness by 40% and improved dispersion of TiO2. The degradation efficiency of Rhodamine B and NO by TiO2@Sand reinforced mortar was 40% and 25% higher than cement matrix with conventionally dispersed nano-TiO2 powder, respectively. The significantly enhanced photocatalytic activity of the TiO2@Sand mortar was attributed to the expanded light absorption range, the reduced recombination of electron-hole pairs of TiO2@Sand, and the better dispersion of nano-TiO2 in cement matrix. These results demonstrated the promising potential of using TiO2@Sand in cement mortar to deliver significant enhancement of both mechanical strength and photocatalytic activity.