Influence of core/shell TiO2@SiO2 nanoparticles on cement hydration

TiO2@SiO2 nanoparticles with a core/shell structure widely used in photocatalytic fields were used in this paper to improve the hydration properties of the Portland cement. To this end, the core/shell TiO2@SiO2 nanoparticles were synthesized first and then characterized by a series of techniques including transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectra (XPS). Second, the influence of the core/shell TiO2@SiO2 nanoparticles on cement hydration was investigated and compared with nano-TiO2 through isothermal calorimetry, XRD, thermo gravimetric/derivative thermo-gravimetric (TG/DTG) and mercury intrusion porosimetry (MIP) analyses. The results showed that an amorphous SiO2 layer can be deposited uniformly on nano-TiO2 particles by forming new SiOTi chemical bonds at the interface between the SiO2 coating layer and nano-TiO2 particle surface. This uniform layer was conducive to decrease the aggregation of nano-TiO2 effectively. Compared with nano-TiO2, the core/shell TiO2@SiO2 nanoparticles exhibited better hydration properties in terms of accelerated cement hydration, higher degree of hydration and lower porosity, even though both particles modified cement hydration.