Effect of waste sandstone microfines on mechanical strength, abrasion resistance, and permeability properties of concrete

Abstract

River sand is a non-renewable resource. The erosion of rocks obtains it, taking thousands of years. The mining of river sand is increasing exponentially due to rapid economic growth and urbanization. Due to a shortage of river sand, low-quality river sand is being used in construction. Concrete can be made more resource-efficient and sustainable by using waste and recyclable materials for sand. Nowadays, manufactured sand (M-sand) is being utilized in construction to lessen the natural sand demand. Higher fines content, angular shape of particles, increased surface area, and rough texture are the key characteristics of M-Sand. The prime focus of this research article is to evaluate the potential of sand made from quarry waste of sandstone to be used as a 100 per cent replacement of river sand in concrete. Waste sandstone microfines were also used and replaced with fine aggregate from 5 to 25%, by weight with an increment of 5%. The generation of microfines is an unavoidable part of the sand manufacturing process. Microfines are particles of size less than 75 µm. These microfines are discarded through sieving or washing, resulting in a waste of our valuable and non-renewable natural resources. The effect of the w/c ratio and sandstone microfine content on the workability, mechanical strength, abrasion resistance, permeability, and ultrasonic pulse velocity of concrete is demonstrated in this paper. The tests revealed that M-sand and microfine content significantly influence concrete's fresh and hardened properties. The strong interlocking of M-sand particles and the filler effect caused by microfines improved concrete's mechanical strength and durability parameters. However, this positive impact of microfines in concrete is lowered by the higher entrapped air at a low w/c ratio. This study establishes that using moderate amounts of sandstone microfines in M-sand can be a sustainable approach to solve the problem of natural sand shortage and reduce the loads from landfills.