Properties and Geotechnical Behaviour of Cemented Tailings Backfills with Additive-Enhanced Performance under Different Thermal and Mechanical Loading Conditions

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Canada is one of the largest mining nations in the world. However, this industry is associated with the production of a large quantity of solid waste, especially tailings. The sustainable management of tailings is a great challenge for Canada. One of the most successful and innovative tailings management strategies is the development of cemented paste backfill technology (CPB, a mix of tailings, water and binder). The key functions of CPB, a vital component of underground mine operations, are the mechanical stabilization of underground mine openings, and the maximization of safe and economic ore recovery. In addition, the maximum underground disposal of tailings represents significant environmental benefits. The key performance characteristics of any type of CPB include: mechanical stability under static loading conditions, mechanical stability at the early ages under dynamic loading conditions (liquefaction potential), flowability and cost. One of the key priorities in CPB technology is the development of new types of CPBs that have high mechanical stability with a shorter curing time (increase mine productivity), and improved and/or excellent flowability at an acceptable cost. To achieve this goal, the mining industry and mine backfill engineers have been placing strong emphasis on the use of novel types of additives (chemical admixtures, nanoparticles) in CPB in recent years to develop new types of CPB. However, many previous attempts to develop these new types of CPBs and their field applications have produced disappointing results or failed due the lack of a sufficient and basic understanding of the behaviour and performance of CPBs that contain such additives as well as due to the lack of consideration of the coupled thermo-mechanical (TM) loading conditions to which these CPBs are subjected in the field. The lack of consideration given to these coupled TM processes has long been defended on the basis that it is difficult to do so. However, this does not mean that these issues are not essential. Innovative thinking is needed to face these challenges and thus address this deficiency in technology. Therefore, novel methods and tools for studying the response (e..g, mechanical stability, liquefaction potential) of these new types of CPBs: (CH-CPB or CPB with chemical admixtures; nano-CPB or CPB that contains nanoparticles) to TM loads in static and dynamic loading conditions as well as for assessing the flowability of these types of CPBs under various thermal conditions in mines, and for preparing optimal backfill recipes are identified and proposed in this research program. These tools and a thorough understanding of the behaviour and performance of these new types of CPBs under various field TM loading conditions are imperative and essential for economic reasons, mine worker safety and the development of economically and environmentally sustainable mining strategies.*****