Mechanical properties and microstructure of high performance concrete containing stabilized nano-silica

Nanotechnology can significantly improve the mechanical strength and durability of concrete. At thenanoscale, good dispersion of constituent materials is an essential factor for the improvement of concreteproperties. In this scenario, the objective of this research was to evaluate the mechanical properties of highperformance concrete containing stabilized nano-silica. The incorporation of nano-silica to thepolycarboxylate chemical admixture allowed its application in concrete, since the nano-silica was evenlydispersed in the concrete mass. For this study, three different concretes were employed: a reference concrete,one containing stabilized nano-silica and another containing a mixture of silica fume and stabilized nanosilica.The evaluated concrete mechanical properties were the axial compressive strength and secant modulusof elasticity measured in three different ages. The results indicated a substantial increase in concretecompressive strength and modulus of elasticity with the addition of stabilized nano-silica combined with areduction in cement content. The results also showed that use of stabilized nano-silica proved to be veryadvantageous, especially when mixed with silica fume. When they were combined, a synergy effect occurredin the concrete that was of chemical nature in addition to the physical effect of better concrete particlepackaging. Analysis by scanning electron microscopy showed the improvement in microstructure ofconcretes with stabilized nano-silica, which contributed to gains in mechanical properties