Influence of nano-SiO2 on the Portland cement pastes

The evolution of nanotechnology provides materials with new properties and over the last years a lot of effort has been put to introduce nano-particles into cement pastes in order to improve their properties and to produce materials of better performance. In the present research work, nano-SiO2 produced by pyrolysis and with specific area of 200 m(2)/g has been added at different percentages (0%, 0.5%, 1%, 2% and 5%) to high-strength cement pastes. These pastes were tested for their mechanical and structural properties at different ages. Nanoparticles act as nuclei for crystallization and large, idiomorphic crystals of Ca-Si composition were formed assisting, up to a certain percentage, in producing materials with dense structure, reduced porosity and improved strength. (C) 2012 Elsevier Ltd. All rights reserved.