The coupling between desiccation and consolidation is a process with important implications for the management of soft soils in general and dewatering of fine grained tailings typical of phosphate, bauxite, and oil sands mining in particular. The management of fine tailings can involve the placement of layers that are allowed to desiccate, and then are subsequently consolidated by burial under fresh tailings. While desiccation does densify the material, it also changes both the strength and volume change behaviour of the subsequently consolidated material. This phenomenon is crucial to the oil sands industry, where regulations mandate that tailings achieve a set undrained strength within 1 year after deposition. To understand the interplay of desiccation and consolidation, the evolution of microstructure of oil sand fine tailings are tracked through different drying and consolidation paths using mercury intrusion porosimetry, and non-biased analyses of Environmental Scanning Electron Microscope images. Preliminary results presented in this paper describe the evolution of microstructure in polymer amended tailings during desiccation. The influence of flocculant dose on the microstructure appears to lessen as desiccation progresses, but the final microstructure retains a more open porosity compared to untreated tailings. Résumé.

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Keywords Desiccation, Mature fine tailings, Mercury intrusion porosimetry, Microstructure, Polymer, SEM, Suction
Conference 18th International Conference on Soil Mechanics and Geotechnical Engineering, ICSMGE 2013
Bajwa, T. (T.), & Simms, P. (2013). Evolution of microstructure during desiccation of oil sands mature fine tailings. In 18th International Conference on Soil Mechanics and Geotechnical Engineering: Challenges and Innovations in Geotechnics, ICSMGE 2013 (pp. 1085–1088).