Yield stress and strength of saline cemented tailings materials in sub-zero environments: slag-paste backfill

This paper presents the results of an investigation that aimed to evaluate the influence of sodium chloride (NaCl or salt) on the yield stress and evolution of the strength of a cemented tailings material (called cemented paste backfill, CPB) that contains ground granulated blast furnace slag (Slag-CPB) in sub-zero environments. About 200 CPB specimens with different NaCl concentrations (0, 5, 35, and 100 g/L) and cured at −6 °C are tested at different curing times (0, 0.25, 1, 2, and 4 h for yield stress measurement; 7, 28, and 90 days for uniaxial compressive testing). Moreover, microstructural analyses are conducted on cement-slag paste and Slag-CPB samples with various concentrations of NaCl. The results show that the addition of NaCl provides better flowability of the fresh Slag-CPB and significantly affects the strength development of Slag-CPB. The results presented in this study have significant implications for backfill practices in permafrost and cold regions.