Effectiveness of soda residue-activated GGBS as alternative binder on compressive strength and workability of cemented paste backfills: Reuse of multi-source solid wastes

Abstract

• Low-cost multi-source solid wastes are utilized directly processing to prepare CPB. • Effect of SR/SH on behavior of CPB was studied. • The SR proportion has a major effect on UCS of CPB matrix, which accounted for 80% was optimal. • The joint action of C (A) S H, and FS increased the UCS of the filling materials. To address the issues related to heavy environmental pollution and low resource utilisation of soda residue (SR), the study used industrial solid wastes, including SR, ground-granulated blast-furnace slag (GGBS), and iron tailings, to prepare low-cost filling materials. To ensure that the filling materials can be effectively utilised in mine backfill projects, the effects of mass content, GGBS content, activator dosage, and SR proportion on the workability and mechanical properties of the filling materials were investigated. The results indicated that when the mass content was 75 %, the GGBS content was 14 %, the activator-to-binder ratio was 0.4, SR accounted for 80 %, NaOH accounted for 20 %, the fluidity was 267.5 mm, and the 28-d UCS reached 2.4 MPa, at which time the effect of the synergistic activation of the GGBS with NaOH-SR was optimal. According to the results of microstructure testing, the main hydration products generated by NaOH-SR-activated GGBS were C S H gel, C A S H gel, and Friedel’s salt (FS), the contents of which increased with the curing time. With a reduction in the proportion of SR, the FS content decreased, and the content of the C (A) S H gel increased. When the proportions of SR were 80 %, the hydration reaction of SR-NaOH-activated GGBS was sufficient, and the joint action of C (A) S H, and FS increased the UCS of the filling materials.