Performance d'une couverture avec effets de barrière capillaire faite de mélanges gravier-bentonite pour contrôler la migration d'oxygène en conditions nordiques

Environmental reclamation of mine tailing storage facilities is an important challenge of the mining industry. Especially for acid mine drainage (AMD) generating sites located in Nordic conditions where robust reclamation scenarios must be developed. In temperate climate, covers with capillary barrier effects (CCBE) were proven to be a practical reclamation method for AMD generating tailings. However, these covers require a fine grained material for the moisture-retaining layer which, in Nordic conditions, is not always available close to the construction site. In that case, soil-bentonite or crushed rock-bentonite mixtures could be used instead. Therefore, this study aims at evaluating through laboratory testing the performance of CCBEs made of crushed rock-bentonite mixtures to control oxygen fluxes for the reclamation of Nordic mine sites. Cover insulation properties would reduce the period of time where the tailings are above the freezing temperature and would control oxygen fluxes when the tailings could generate AMD in the unfrozen state. The main objectives of this research project are (1) to characterise the hydro-geotechnical properties of cover materials, (2) to develop a laboratory column testing method that allows evaluating the freeze/thaw sensibility of the tested CCBE on oxygen migration and water distribution and (3) to evaluate the capacity of the CCBEs to control oxygen fluxes for different placement conditions before and after freeze/thaw cycles, based on the evaluation of the moisture-retaining layer's effective oxygen diffusion coefficient."