Contribution of core/shell TiO2@SiO2 nanoparticles to the hydration of Portland cement

Abstract This paper presented the contribution of core/shell TiO2@SiO2 nanoparticles to the hydration properties of Portland cement and the contribution was compared with that of nano-TiO2. Both nanoparticles were used to partially replace cement at 1 wt%. The mechanical property and microstructure of the cement pastes were experimentally characterized using compressive strength and scanning electron microscope (SEM), respectively. Specially, thermodynamic modeling was also applied to predict the phase assemblages and calculate the corresponding volumes. The results showed that the paste with 1 wt% TiO2@SiO2 developed a much higher compressive strength than the paste with or without nano-TiO2 added at each curing age. Both SEM and mapping analyses showed that obvious agglomeration of nano-TiO2 could be observed in nano-TiO2 modified cement paste, which decreased its efficiency in the cement paste. However, nano-TiO2 was well distributed when TiO2@SiO2 was added because of its limiting effect on the agglomeration of nano-TiO2, further densifying the microstructure. The calculated hydrates volumes by thermodynamic modeling also indicated that TiO2@SiO2 would result in producing most hydrates of all the pastes, thus contributing to a denser microstructure and a much higher compressive strength development.