The mesostructure evolution of cemented paste backfill during mixing

Mixing plays a crucial role in preparing Cemented Paste Backfill (CPB). Shearing, concentration, and particle size distribution are key factors that impact the flow of CPB slurry. This study employed focused beam reflectance measurement and a torque sensor to monitor the flow and structure evolution of CPB during the mixing process. The mixing process can be divided into three stages based on the torque curve: aggregation, destruction, and equilibrium. The structural evolution is the cause of the flow of fresh CPB. Each stage exhibits distinctive characteristics of the fresh CPB. During the aggregation stage, coarse tailings agglomerate via liquid bridges, binders agglomerate by hydration, and fine tailings interact mostly due to interparticle forces. Since the network is heterogeneous, the structure cannot resist shearing forces during the destruction and equilibrium stages. Finally, a rheological model was developed based on the mesostructure evolution mechanism of CPB. •The focused beam reflectance measurement and the torque sensor is used to monitor the flow and structural evolution of the CPB slurry under mixing.•The mixing process is divided into aggregation, destruction, and equilibrium stage.•The concentration, coarse tailings and binder-to-tailings ratio have an impact on the flow of the CPB slurry.•Agglomerates are dispersed by coarse tailings, and particle aggregation is promoted by fine tailings and binders.