Influence of Additions of Anatase TiO2 Nanoparticles on Early-Age Properties of Cement-Based Materials

The performance and properties of cement-based materials can potentially be altered by the addition of nano-sized inclusions. In this study, the effect of chemically nonreactive anatase TiO2 nanoparticles on early-age hydration of cement was investigated. First, the effects of different percentage addition rates of TiO2 to portland cement on early-age behavior were examined through isothermal calorimetry and measurements of chemical shrinkage. On the basis of accelerations in hydration observed in TiO2 portland cements, additional experiments were performed with tricalcium silicate (C3S), the main strength-giving mineral component of portland cement, to determine whether the influence of TiO2 could be adequately described by a kinetic model that relies on boundary nucleation theory. Comparison of the experimental results and the modeling showed that (a) an increase in addition rates of TiO2 accelerates the rate of cement hydration and (b) the heterogeneous nucleation effect rather than the dilution effect was dominant. The result of the boundary nucleation model reinforces the concept of the heterogeneous nucleation effect and demonstrates that the surface area provided by nano-TiO2 particles increases the rate of hydration reaction. This research forms the foundation for future studies aimed at optimizing photocatalytic and other nanoparticle-containing cements.