Durability investigations of micro and nano silica blended cementitious systems in self-compacting concrete under adverse conditions

Abstract

The colossal magnification of industrialization in recent years led to the snags of squandering materials that harm the environment. To employ the industrial debris into the concrete, can contribute to lower the carbon footprint to some extent. For this purpose, the M60 grade of self-compacting concrete was designed with industrial waste products. Fly ash was used as a constant cement substitute product of 20% of the cementitious systems. Further, silica of micro and nano-sized particles are used as a cementitious replacement in varying percentages from 5% to 15% and 1% to 3% respectively. A total of eight mixes including the reference mix and the combined mix of micro and nano silica were prepared and examined for the fresh state property. The slump flow test, J-ring test, and Orimet test were performed in the fresh state of concrete. Concrete specimens in the hardened state were tested for compression strength and durability characteristics like water absorption, acid attack, and sulphate attack at 7, 28, and 90 days respectively. Further, investigations were carried out on the microstructural behavior when exposed to acid and sulphate attack using a scanning electron microscope (SEM). The hardened state properties of SCC showed positive durability results for the combined mix of 10% micro and 2% nano silica, where better hiking of calcium silicate hydrate gel was observed by the inclusion of binary and ternary blending materials