The effect of stone waste on the properties of cemented paste backfill using alkali-activated slag as binder

The decorative stone processing generates a large amount of stone waste, which is associated with sev-eral environmental problems. This paper investigated the potential utilization of the stone waste (mainly containing calcite and dolomite) in the alkali-activated slag based paste backfill (APB). The effects of stone waste fineness, solid mix proportion and sodium hydroxide to sodium silicate ratio (SH/SS) on the fresh and hardened APB were experimentally studied at 7- and 28-day curing time. Results showed that ultra-fine portion (<20 mu m) of 30%-40% had a more positive effect on the fluidity and mechanical strength of APB. Active calcium from the dissolution of stone waste in high concentration of alkaline solu-tion accelerated the hydration reaction. Besides, increasing of both slag and alkaline solution content enhanced the mechanical strength of APB samples. It was also found that APB with SH/SS of 1 achieved better mechanical performance. These findings will be conducive to the potential application of building stone waste and alkali-activated slag in paste backfill. (C) 2021 Elsevier Ltd. All rights reserved.