Análise da microestrutura de concretos de alto desempenho contendo nanosílica e sílica ativa

Abstract

The use of nanomaterials in concrete has shown promise, as the use of several types of these materials in cementitious compounds have been found to guarantee greater physical-mechanical properties and improvement in concrete microstructure. The use of mineral admixtures like nanosilica and silica fume ensures the improvement of interfacial transition zone (ITZ) between aggregate and paste, which is a weaker part in high-performance concrete (HPC). In this way, the present work intends to evaluate the performance of nanosilica and silica fume in properties of HPC in macro and microstructural properties. Were evaluated the mechanical properties (compressive strength and elastic modulus) and microstructural properties through nanoindentation, scanning electron microscopy, X-ray microtomography and atomic force microscopy of concretes with 1.5 and 3% of nanosilica and 5% and 10% of silica fume. The results indicated that with the use of mineral admixtures the compressive strength and elastic modulus of concrete increase significantly. The microstructural investigations showed that the nanosilica and silica fume leads to a densification of ITZ, which was the main responsible for the improvement of HPC performance.