Propriedades mecânicas do concreto de alto desempenho com adição de nanosílica estabilizada

Abstract

Nanomaterials can improve the mechanical properties and durability of the concretes. For high performance concrete, the good dispersion of materials is an essential factor to improve its properties. The goal of this investigation was to evaluate the mechanical properties of high-performance concrete with the addition of stabilized nanosilica. The influence of this addition in compressive strength, tensile strength by diametrical compression and initial tangent modulus was evaluated at three different ages. It was also evaluated the combination of stabilizednanosílica and Silica Active as supplementary cementitious materials. Three different concrete mixtures were studied: a reference (without nanosílica and without silica fume), other containing stabilized nanosilica and another containing a mixture of silica fume and stabilized nanosilica. The incorporation of the nanosilica in the polycarboxylate superplasticizer contributed to a better application and efficiency of the nanosilica in the concrete, since the nanosilica was easily homogenized in the concrete. The results indicated an improvement in all the mechanical properties ofconcrete from the addition of stabilized nanosílica, even with the reducedconsumption of cement. The effect was even greater with the combination of silica fume and nanosilica, indicating that theres a synergistic effect between the two. The pozzolanic reaction of the additions contributed to the improved performance of mechanical properties of high performance concrete. The results also revealed that nanosílica is very advantageous, especially when mixed with the silica fume, and can be a good alternative to produce concrete with high mechanical strength, reduction in cement content and economy.