Analysis of mechanical and microstructural properties of high performance concretes containing nanosilica and silica fume

Abstract

The use of nanomaterials in concrete has shown promise, and the use of several types in cementitious compounds has been found to guarantee greater physical-mechanical properties and improvements in microstructure. The use of mineral admixtures, such as silica fume, ensures the improvement of the interfacial transition zone (ITZ) between aggregate and paste in high-performance concrete (HPC). Thus, this work evaluates the performance of superplasticizer additive with colloidal nanosilica suspension and slurried silica fume with HPC and its macro-and micro-structural properties. The mechanical (i.e., compressive strength and elastic modulus) and microstructural properties via (scanning electron microscopy and X-ray micro tomography) of concretes with 1.5 and 3% nanosilica and 5 and 10% silica fume included in the evaluation methods in this study. The results indicate that, with the use of mineral admixtures, the compressive strength and elastic modulus of concrete increased significantly. The concrete with the use of 10% silica fume and 3% nanosilica resulted in a showed an increased strength over 75% at 28 days. Besides that, for same w/b = 0.35 the elastic modulus increased by 36% compared with the reference concrete. The microstructural investigations show that the nanosilica and silica fume led to a densification of microstructure, which is responsible for the improvement of HPC performance.

Evaluating the effect of autoclave curing on the microstructure and compressive strength evaluation of a high strength concrete

“…With the further improved density and homogeneity, UHPC possesses outstanding mechanical properties and durability [2,3]. Concrete research and practice have shown that HSC uses silica fume and/or other pozzolanic materials at content lower than 10% by mass of Portland cement, while UHPC uses those materials at content higher than 20% [4,5].…”