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 Si-O-Ti 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. (C) 2017 Elsevier Ltd. All rights reserved.