Effect of marble slurry on the microstructure of cement mortars subjected to salt crystallization and alternate wetting and drying cycles

Abstract

The scarcity of river sand has triggered the utilization of industrial waste to produce concrete and mortars. One such waste is marble slurry, which is being produced in huge quantities during marble processing, was evaluated as a partial substitute to sand for the production of mortars. This study aims to assess the properties of mortar mixes of proportions 1:3 and 1:6 made with dried marble slurry of dolomitic origin by substituting 20 and 30% of fine aggregate. It was observed that mortars could be produced with lesser water content on the incorporation of this waste. This has helped improve compressive strength, while properties like tensile and flexural strengths, water absorption are comparable to conventional mortars. On examining the microstructure using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction, the augmented formation of tobermorite and gismondine like minerals on cement hydration were detected. Traces of dedolomitization of the dolomitic marble were also identified along with the formation of calcium carbo-aluminates, enhancing the quality of the microstructure and mechanical performance. While the phenomenon of salt crystallization restricts the usage of dried marble slurry for the production of mortars with a rich mix proportion of 1:3 only, alternating cycles of wetting and drying do not significantly affect the performance of both 1:3 and 1:6 proportions on the usage of dried marble slurry as fine marble slurry.