Utilization of granulated marble wastes and waste bricks as mineral admixture in cemented paste backfill of sulphide-rich tailings

This study presents the utilisation of granulated marble wastes (MW) as an additive (10-30 wt%) and waste bricks (WB) as replacement and additive (15-45 wt%) to ordinary Portland cement (OPC) for cemented paste backfill (CPB) of sulphide tailings. OPC was used as binder at 7 wt% dosage. Pozzolanic activity tests showed that the fineness of the WB samples, not the chemical composition, is the major factor affecting their pozzolanic activity. Although they do not exhibit any pozzolanic activity, the use of MW samples as an additive to OPC improves acid buffering capacity of CPB samples and enhances their short and long-term mechanical performance. The UCSs of CPB samples increased with increasing additive rates and decreased with increasing replacement ratios. All CPB samples produced the desired strength and durability when MW and WB were used as an additive to OPC. However, a binder dosage of >7 wt% was required to produce the desired 28-day strength of ≥0.7 MPa when the OPC was replaced by 15-45 wt% WB samples. The durability (i.e. no loss of strength) of CPB samples is closely inter-related with the calcination temperatures and glass phase content of WB.