Coupled Behavior of Cemented Paste Backfill at Early Ages

Once cemented paste backfill (CPB) is poured into a mine stope, it is subjected to strong coupled thermal (T), hydraulic (H), mechanical (M) and chemical (C) processes. A laboratory investigation is performed to understand the THMC behavior of CPB at early ages. An experimental setup is developed to study the THMC behavior of CPB. The testing and monitoring are conducted in undrained conditions, with and without pressure application, and take into consideration two types of tailings (artificial and natural). The evolutions of the total pressure, pore pressure, suction, temperature and electrical conductivity are monitored for a period of 7 days. Also, the CPB samples are tested or analyzed with regards to their shear strength properties, hydraulic conductivity, thermal conductivity, and physical and microstructural characteristics at 1, 3 and 7 days. The obtained results show that the THMC properties of CPB are strongly coupled due to several mechanisms, such as curing stress, heat of hydration, self-desiccation and pore fluid chemistry. The results presented in this paper will provide a better understanding of the THMC behavior of CPB at early ages and thus contribute to the better designing of CPB structures. © 2015, Springer International Publishing Switzerland.