Abstract Conventional OPC-based mine backfills face challenges of high carbon emissions and slow early-strength gain, while mine solid wastes pose environmental risks. This study developed an alkali-activated aluminate cement-fly ash (AC-FA) binder (ACCM) to bridge this gap, focusing on fabricating high-performance composite stone cemented bodies (CSCB). The primary objective was to optimize the mix design for structural backfill applications. Using Principal Component Analysis (PCA) and Response Surface Methodology (RSM), three key parameters—water-cement ratio, fly ash content, and alkali content—were evaluated. Based on PCA weights for strength, setting time, and viscosity, the optimal mix was determined as: water-cement ratio of 0.6, fly ash content of 3.8%, and alkali content of 1.5%. Microstructural analysis (SEM–EDS) confirmed that matrix densification and C-(A)-S-H gel formation shifted the mechanical behavior from plastic to brittle. Additionally, a discrete element model (DEM) using 3D-scanned flexible clusters in PFC3D was developed. By implementing a 0.6 reduction factor for the Interface Transition Zone (ITZ) properties, the model accurately captured the experimental stress–strain curves and interfacial debonding failure. These findings provide a robust framework for high-strength, eco-friendly mine backfill design, promoting the high-value utilization of industrial solid wastes.
Qin et al. (Tue,) studied this question.