Hydration and properties of nano-TiO2 blended cement composites

Two types of nano-TiO2 particles were blended into cement pastes and mortars. Their effects on the hydration and properties of the hydrated cement pastes were investigated. The addition of nano-TiO2 powders significantly accelerated the hydration rate and promoted the hydration degree of the cementitious materials at early ages. It was demonstrated that TiO2 was inert and stable during the cement hydration process. The total porosity of the cement pastes decreased and the pore size distribution were also altered. The acceleration of hydration rate and the change of microstructure also affected the physical and mechanical properties of the cement-based materials. The initial and final setting time was shortened and more water was required to maintain a standard consistence due to the addition of the nano-TiO2. The compressive strength of the mortar was enhanced, practically at early ages. It is concluded that the nano-TiO2 acted as a catalyst in the cement hydration reactions. (C) 2012 Elsevier Ltd. All rights reserved.