Unsaturated Flow in Hydrating Porous Media: Application to Cemented Paste Backfill

Sustainability of hardrock mining is contingent upon delivering a high quality cemented paste backfill (CPB) that is self-sustaining during ore recovery. The integrity of CPB systems hinges on how quickly in excess pore-water pressures (PWPs) dissipates. Consolidation and self-desiccation are critical factors that determine how rapid PWPs expel in hydrating CPB.Current models characterize stress distributions in CPB based on fully saturated / undrained conditions. Recent studies suggest that such conditions are not entirely valid. This research therefore, describes PWP behaviour in CPB by using an unsaturated flow theory framework that takes into account self-desiccation.The analyses involved capturing the experimental lower and upper bound water-retention properties of CPB. These properties are then used to solve a modified 1-D unsaturated flow equation of hydrating CPB material. Numerical predictions of PWPs in a column test were well simulated when comparing these results with the experimental measurements.