Laboratory evaluation of hydraulic conductivity and chemical compatibility of bentonite slurry for grouting walls

摘要

The hydraulic conductivity and chemical compatibility of bentonite slurry for grouting walls were evaluated. Bentonite slurry of different concentrations and volumes was injected into fine-sand, medium-sand and coarse-sand aquifers. The results indicated that bentonite slurry was a fast and highly efficient grouting material. After injection into aquifers, a low-permeability zone could be formed immediately near the injection point. Through 24 groups of experiments, it was determined that bentonite slurry with concentrations of 6%, 7% and 10% and volumes of 0.6 PV, 0.8 PV and 0.6 PV, respectively, was required to meet the hydraulic conductivity requirement of cut-off walls for fine-sand, medium-sand and coarse-sand aquifers. In addition, the chemical compatibility of bentonite slurry was investigated to investigate its applicability as grouting wall material at waste containment facilities. Permeation with 50 mM H2SO4 solution resulted in an increase in the hydraulic conductivity by a factor of 65-73 times. The suitable pH of the bentonite slurry grouting wall ranged from 2.0 to 13.0. The hydraulic conductivity increased by a factor of approximately 4.7-54 during permeation with 10 similar to 1000 mM CaCl2. Bentonite slurry grouting walls cannot be applied in environments with salt concentrations greater than 10 mM. In contrast, permeation with 10 mM phenol solutions resulted in no appreciable change in hydraulic conductivity. Bentonite slurry grouting walls are appropriate for environments with dissolved organic pollution.