Effect of Waste Materials on the Strength-Stability Performance and Production Cost of Cemented Paste Backfill

Abstract

In this study, the effect of the waste materials (WMs) (construction-demolition waste: CDW, limestone: LS, fly ash: FA and blast furnace slag: BFS), replaced at 15wt.% to sulphide-mine tailings (S-MT) in cemented paste backfill (CPB) mixture, on the strength/stability performance and production cost of CPB were examined. Within this scope, CPB samples (Control and 15wt.% WM) were subjected to the strength tests for 7-360 days. To investigate the production cost of CPB, the amount and costs of the binder were determined, while the energy consumption and costs of the WMs during grinding were calculated. All samples provided the desired 1.0 MPa strength in the short- and long-term, and CPB samples containing 15wt.% FA and BFS produced up to 4 times higher strength than the Control. 130.0 kg cement was used in Control mixture for 1.0 m3 CPB production, whilst reducing the binder dosage by 1.0% in the CPB mixture with WM resulted in approximately 15% cement savings. During the grinding process of WMs, 6.55-18.89 kWh/ton of electric energy was consumed; thus, 2.99₺ (FA)-8.85₺ (CDW) of money was spent. When the total cost for CPB production was evaluated, 153.4₺ was spent for the Control mixture, whereas it was foreseen that the cost of backfill mixtures of 15wt.% WM can be reduced to 133.5₺ (saving up to 12.98%). The results demonstrated that the most suitable mixture type for CPB's strength/stability performance and production cost is the CPB mixture of 15wt.% FA.