Effect of nano-silica on Portland cement matrix
AbstractThe use of nano-particles is a current trend that may play an important role in the efficient use of Portland cement. The aim of this study is to evaluate the effect of nano-silica on Portland cement matrix. The particle size distribution of Portland cement matrix was modified by the incorporation of 11, 6.2, 3.1, 1.7, 0.85 and 0.42 wt.% of nano-silica. The water demand and the dispersant consumption were adjusted, and rheological properties of suspensions were analyzed through rotational rheometry. The mechanical performance of studied mixtures was evaluated by the compressive strength. The pore size distribution was measured by mercury intrusion porosimetry (MIP), and hydration was analyzed through X-ray diffractometry. The rheological behavior presents a considerable change, as a consequence of high specific surface area of nano-particles. The optimum nano-silica content, or the smaller quantity of nano-particles that lead to the maximum strenght gain, varies according to the water to powder ratio. An increasing on the hydration and the refinement of pores were obtained due to the use of silica nanoparticles. The particles packing and the pozzolanic reaction are the two main effects of nano-silica on the microstructure of Portland cement matrix.