Coupling reinforcement of uranium tailings via Klebsiella-induced calcium carbonate precipitation and waterborne polyurethane

The environmentally friendly and efficient realization of uranium tailings dam reinforcement is of great sig-nificance for the sustainable development of the uranium mining industry. Herein, the effects of microbially induced calcium carbonate precipitation (MICP), using Klebsiella, and waterborne polyurethane (WPU) coupled reinforcement on the mechanical behavior of uranium tailings were studied by triaxial testing. It was demon-strated that the mechanical behaviors of the specimens treated with MICP-WPU coupled reinforcement had a more significant improvement than those treated with MICP alone. When the test confining pressure was 400 kPa, it was found that the peak deviatoric stress of the specimens treated with the coupled reinforcement increased by 45.7 %, the elastic modulus increased by 231.3 %, and the cohesive force was enhanced to 217 kPa as compared to the specimen reinforcement of only MICP induced by Klebsiella. The coupled reinforcement mechanism study using XRD and SEM shows that the significant improvement in the mechanical behavior of the specimens is attributed to the spatial reticular structure formed by wrapping and binding vaterite crystals and tailings particles with WPU. This innovative green reinforcement method is expected to be a new alternative for stabilizing unstable soils in mine geotechnical engineering.