Study on properties, mechanism and carbon benefit of cementing tailings backfill with full solid waste binder

The synergistic effects of full solid waste binder (FWB) on the performance of cemented tailings backfill (CTB) require in-depth investigation. In this study, the performance, mechanism and carbon emission benefit of FWB CTB are systematically investigated. Experimental results revealed that slurry fluidity is significantly reduced with increasing content of alkaline slag in FWB. Notably, ground granulated blast-furnace slag (GGBS) exhibited a more pronounced fluidity-reducing effect compared to steel slag. The compressive strength of CTB is gradually decreased as the FWB-to-tailings ratio decreases. Remarkably, at a 1:10 FWB-to-tailings ratio, the A4 CTB achieved 116% higher compressive strength than conventional cement CTB. Field trials confirmed the practical viability of FWB CTB, with engineering strength reaching 2.3 MPa, which exceeding the 1.8 MPa of design requirement. A4 CTB at a 1:6 FWB-to-tailings ratio demonstrated a 49% reduction in 14d drying shrinkage relative to cement CTB. More ettringite (AFt) was generated in A4 CTB, coupled with a substantial porosity reduction of 5.5%. A larger number of pores and unreacted particles was found in A7. The superior performance of FWB CTB is attributed to three synergistic mechanisms: (1) development of a denser CTB micro-structure, (2) increased formation of hydration, and (3) inherent shrinkage compensation capabilities. FWB exhibit a reduction of over 95% in carbon emission compared with Portland cement. A decrease in the FWB-to-tailings ratio, by contrast, results in a unexpected rise in carbon emission normalized to unit compressive strength.