Influences of nano-TiO2 on the properties of cement-based materials: Hydration and drying shrinkage

To better understand the influences of nano-TiO2 on the properties of cement-based materials, the hydration process, the compressive strength development, and the drying shrinkage of cement-based materials with the addition of nano-TiO2 of 25 nm were investigated. Results showed that nano-TiO2 increased the compressive strength of cement mortar through its acceleration on cement hydration and the pore-refining effect: 5 wt.% nano-TiO2 accelerated cement hydration process for 2 h and reduced the most probable pore size by 19.4%, 48.5%, and 54.4%, respectively. In addition, the influences of the hydrophilicity of nano-TiO2 on the water loss and volume stability of hardened cement pastes were primarily investigated and discussed in this work. For a comparison study, nano-SiO2 of 30 nm size was also used. Results showed that the decline of the contact angle and the refining of pore structure with the addition of nano-TiO2 slowed down the water loss of hardened cement paste, which resulted in a comparable drying shrinkage to that of the control sample at 1 month age.