Curing time effect on consolidation behaviour of cemented paste backfill containing different cement types and contents

The one-dimensional consolidation properties of early age cemented paste backfill (CPB) are useful for the estimation of design parameters for underground stope filling purpose as well as for numerical modelling purposes. Many studies have investigated the consolidation characteristics of mine tailings, but not in CPBs, mainly because consolidation was not initially considered as an essential property and the available testing equipment was not suitable. In this paper, the curing time effect of different types of binder and their content on the one-dimensional consolidation characteristics of CPB samples was investigated using an improved lab apparatus called CUAPS (curing under applied pressure system). As the drainage ability and the saturated hydraulic conductivity ksat are closely linked with consolidation, the change in the ksat at the end of the consolidation process was also investigated for tailings (control) and CPB materials. Results indicate that adding binder to the mixtures considerably affects the void ratio and increases compression resistance. The excess pore water pressure indicates that binder reduces the peak value reached for all pressure increments while the ksat decreases with time. Some empirical equations to estimate the one-dimensional consolidation characteristics of CPB samples are finally proposed and discussed.