Impact of cyclically infiltration of CaCl2 solution and de-ionized water on volume change behavior of compacted GMZ01 bentonite

During the long-term operation of a geological repository, fluctuations of groundwater level, temperature, etc., will lead to cyclically changing of groundwater chemical components correspondingly, resulting in influencing the volume change behavior of compacted bentonite. Using an improved expansion apparatus, one-dimensional free swelling tests were conducted on as-prepared densely compacted GMZ01 bentonite specimens, which have an initial dry density of 1.70 g/cm3, with cyclically infiltration of CaCl2 solutions at different concentrations and de-ionized water. Four concentrations (0.1, 0.5, 1.0 and 2.0 M) of CaCl2 solutions and de-ionized water were employed for the infiltration tests and four salinization-desalinization cycling paths were followed. Results show that the total swelling strains of compacted GMZ01 bentonite specimens were influenced by the concentrations of infiltration CaCl2 solutions, the salinization or de-salinization processes, as well as the cycles of salinization-desalinization experienced.