Engineering properties and sustainability evaluation of crushed low grade magnesite mortars

Abstract

China is the country in the world with the most abundant magnesite resources. The ever-increasing deposit of low grade magnesite ore derived from the process of magnesium products has occupied a substantial space and caused environmental damages. In this study, crushed low grade magnesite (CLGM) was prepared and then applied in mortar as fine aggregate to partially or entirely replace natural river sand (30%, 60%, and 100%), while 100% limestone sand (LSS) was applied as the reference group. The findings of this study demonstrated a positive correlation between the ratio of CLGM substitution and the improvement of both engineering properties and sustainable potential in the mortar. Compared with the control group at 28 d, the 100% CLGM mortar exhibited improvements of up to 6% in splitting strength, 25.86% in compressive strength, 16% in porosity reduction, 22.22% in impermeability enhancement, 27.52% in resistance to chloride ion penetration, 21.66% in frost resistance (after 150 cycles), and a remarkable 54.8% in anti-abrasion property. Furthermore, the sustainability evaluation assessed its potential societal value, and highlighted its reduced production costs (down 52.28%) and impressive environmental benefits (notable decreases of 28.3% in ozone depletion potential, 33.2% in land use potential, 38.7% in marine ecotoxicity, and 33.9% in fossil resource scarcity). These findings well demonstrated the feasibility of adopting magnesite tailings as a substitute of conventional aggregate within the construction sector along with substantial economic savings and positive environmental ramifications. The successful application of CLGM mortar in cleaner production can further facilitate the sustainable advancement of environment and construction industry.