Effect of total substitution of crushed limestone sand on concrete durability

Abstract

This article examines the effect of total substitution of siliceous sand by crushed limestone sand in mortar and concrete with regard to durability. Crushed limestone sand is a by-product of quarries containing a significant amount of fines characterised by a ‘spread out’ grain size distribution having a maximum diameter of around 5 mm. An extensive laboratory program was planned to achieve the objectives of this study. Effect of sand replacement on transport mechanism was analysed for two different water/cement ratio by pure diffusion and accelerated migration tests conducted on mortar and concrete samples, respectively. Gas permeability, resistance to strength development under saline curing, carbonation and corrosion tests were also done. The results have indicated the suppression of chloride diffusion coefficients in both mortar and concrete specimens for crushed sand as compared to the siliceous sand. For a given water to cement ratio, the gas permeability coefficients have reduced more than twice for crushed sand as compared to siliceous sand. In addition, the crushed sand concrete has shown better resistance against the strength development in saline curing conditions and corrosion. However, the carbonation depth was observed to be on the higher side for crushed sand as compared to the siliceous sand.