Effects of salt solutions on the hydro-mechanical behavior of compacted GMZ01 Bentonite

In this study, the effects of salinity of infiltrating solutions on the swelling strain, compressibility, and hydraulic conductivity of compacted GMZ01 Bentonite were investigated. After swelling under vertical load using either distilled water or NaCl solutions with concentrations of 0.1, 0.5 M, and 1 M, laboratory oedometer tests were conducted on the compacted GMZ01 Bentonite. Based on the oedometer test results, hydraulic conductivity was determined using the Casagrande’s method. Results show that the swelling strain of highly compacted GMZ01 Bentonite decreases as the concentration of NaCl solution increases. The compression index Cc* increases and then turns to decrease with an increase in the vertical stress or a decrease in the void ratio for different solutions, and the Cc* decreases as the concentration of NaCl solution increases. The secondary consolidation coefficient Cα increases linearly with the increase of the compression index Cc*. Furthermore, a bi-linear relationship between the swelling index Cs* and the secondary consolidation coefficient Cα can be characterized clearly. The hydraulic conductivity increases as the concentration of NaCl solution increases, however, this increase can be prevented if a high confining stress is applied.