Strength evolution and deformation behaviour of cemented paste backfill at early ages: Effect of curing stress, filling strategy and drainage

In this study, a pressure cell apparatus is developed to investigate the early age evolution of the strength and deformation behaviour of cemented paste backfill (CPB) when subjected to various loading conditions under different curing scenarios. The different curing scenarios that are simulated include: (1) drained and undrained conditions, (2) different filling rates, (3) different filling sequences, and (4) different curing stresses. The findings show that drainage, curing stress, curing time and filling rate influence the mechanical and deformation behaviours of CPB materials. The coupled effects of consolidation, drainage and suction contribute to the strength development of drained CPB subjected to curing stress. On the other hand, particle rearrangement caused by the applied pressure and suction development due to self-desiccation plays a significant role in the strength gain of undrained CPB cured under stress. Furthermore, curing stress induces slightly faster rate of cement hydration, which can contribute to strength acquisition.