Time- and Temperature-Dependence of Rheological Properties of Cemented Tailings Backfill with Sodium Silicate

Abstract

Cemented paste backfilling is a novel tailings-management method that is widely used in the mining industry to minimize the environmental and geotechnical risks associated with traditional mine-waste management techniques, ensure safe work conditions in underground mines, and increase mine productivity. To enhance the early age strength of cement paste backfill (CPB), sodium silicate has been proposed and adopted as an admixture in CPB systems due to its activation ability. However, no studies have been done to gain insight into the effect of temperature on the rheological properties (yield stress and viscosity) of CPB with sodium silicate and different types of binders, although a CPB with sufficient flowability is critical for its successful application, and CPB is subjected to various temperatures in the field during its transport. Thus, this study aims to investigate the effect of temperature (2°C, 20°C, and 35°C) and time (0–4 h) on the rheological properties (yield stress and viscosity) of CPB samples with different amounts of sodium silicate (0%, 0.1%, 0.3%, and 0.5%) and different binders. The results show that the yield stress and viscosity of CPB with sodium silicate increase with time and temperature. It is also found that the partial replacement of portland cement with blast furnace slag or fly ash enhances the flowability (reduces the rheological properties) of CPB, regardless of the temperature. Also, an increase in the sodium silicate dosage will increase the yield stress and viscosity of CPB at any temperature. The findings of this research will contribute to a more efficient design of CPB transportation systems.