Investigating the potential of dimensional sandstone waste used as a 50% replacement to sand in mortar for masonry

The genesis of this research is the idea of using dimensional sandstone mining waste in construction to reduce dependence on natural resources like clay, natural river sand and topsoil. The waste produced by the sandstone mining sector ends up in landfills and is a serious environmental concern. The main aim of this study is to evaluate the potential of waste generated in the form of wet slurry during the extensive quarrying and mining of dimensional sandstone. The efficacy of different percentages of sandstone cutting waste (SSCW) as a partial replacement of natural river sand (NRS) in the mortar was evaluated for workability, water/cement ratio, compressive strength and field bond test, to arrive at a preferred recipe (i.e. 50% replacement by SSCW). The novel mortar, with a cement: lime: fine aggregate proportion of 1:0.5:4.5, was further tested for modulus of elasticity, flexural strength and drying shrinkage. The microstructure of mortar was evaluated by XRD and SEM techniques. Different masonry assemblages in the form of stack-bonded prisms, triplets and couplets were cast using this mortar and 3 brick variants to evaluate the performance of masonry under compression, flexure and bond strength in tension and shear. The brick variants used are the novel patented bricks developed by the authors Modi and Gajjar (sand-free unfired brick and manufacturing method therof. Patent No 372690. Granted for 20 Years by The Patent Office, Government of India, 2021), fly ash and burnt red clay bricks. The test results reveal that 50% replacement of NRS with SSCW helps to achieve a strong and stiff mortar with a compressive strength of 18 MPa and modulus of elasticity in the range of 13.5–14.5 GPa. The masonry cast using patented brick and this mortar outperforms the fly ash brick masonry and burnt red clay brick masonry in terms of compressive, flexure and bond strength and is more environmentally friendly.