Strength and microstructural evolution of alkali-activated slag-based cemented paste backfill: Coupled effects of activator composition and temperature

The activator concentration/silica modulus and curing temperature play critical roles in the engineering performance of alkali-activated slag-based cemented paste backfill (AAS-CPB). Different types of AAS-CPB samples, as well as CPBs made of OPC, were tested at different curing times and temperatures (10 °C, 20 °C, 30 °C, and 40 °C). The results show that the strength of AAS-CPB is more sensitive to changes in curing temperature, and the strength of AAS-CPB is consistently higher than that of CPB made of OPC. Moreover, the strength evolution of AAS-CPB is strongly affected by the coupled effect of curing temperature and activator concentration/silica modulus. An increased activator concentration and a reduced silica modulus can improve the early strength of AAS-CPB under a low curing temperature, but it can also weaken the improvement in the late strength of AAS-CPB under warmer curing temperatures. These findings could contribute to successful application of AAS binder to the mine backfill operation.