Abstract: Backfill mining operations are increasingly being performed in cold regions or even permafrost areas. The water available for the preparation of mine backfill is often naturally saline. Further, in some extremely cold regions, anti-freezing agents are often used to avoid the freezing of the paste during the pipeline transportation. This study, the time-dependent evolution of uniaxial compressive strength and initial elastic modulus of cemented paste backfill (CPB) with different saline concentrations (NaCl) at ?6 ℃ was experimentally investigated. Uniaxial compressive tests were conducted on various CPB samples for different curing times (7, 28 and 90 days). The results show that the strength of CPB decreases with the addition of NaCl. All of samples experience an increase in strength with increasing curing time, due to the ongoing cement hydration. Moreover, there exists an obvious linear relationship between the uniaxial compressive strength and the initial elastic modulus, regardless of salinity, curing time and binder type. The results of this investigation could provide some technical information for the implications for backfill practices in cold regions.

Key words: saline cemented tailings backfill, freezing, strength, initial elastic modulus