Effect of nanosilica on characterization of Portland cement composite

Both the filling effect and the pozzolanic reaction make siliceous materials as one of major ingredients of high-performance Portland cement-based composites. Hence, the introduction of nanosilica with finer particle size and larger silicon dioxide to the composite becomes a great deal of interest in recent years. In this study, a liquid-form of nanosilica particle with a spherical diameter of about 20 nm was incorporated into the Portland cement paste at five different dosages and analyzed at four different ages to identify the nanosizing effects on the microstructures and material properties of composite cement paste. Experimental results show that the Portland cement composite with 0.60% of added nanosilica by weight of cement has an optimum compressive strength, in which the increase of compressive strength is about 43.8%. Moreover, the corresponding nanosilica paste of one portion of water mixed with nanosilica of 1.08 wt.% of water has the maximum absolute value of zeta potential of 41.3 mV. Properties through the analyses of NMR, BET and MIP also indicate that the microstructure of Portland cement composite with nanosilica evidently has a more solid, dense and stable bonding framework.