Effects of Freeze-Thaw Cycle on Permeability and Compression Properties of Aeolian Soil-Bentonite Mixture

This research investigates the permeability and compressibility performance of aeolian-Na/Ca-bentonite mixtures (ANB/ACB) with varying bentonite contents, subjected to different freeze-thaw cycles, in which the particle size analysis, permeability tests, and compression tests are employed. The results indicate that: (1) with increasing bentonite content, ANB/ACB exhibits a gradual rise in uniformity coefficient, curvature coefficient, clay content, and compression index (Cc), accompanied by a decrease in permeability coefficient. Moreover, ACB's compression index gradually surpasses that of ANB. Under equivalent bentonite content, ACB demonstrates higher values for non-uniformity coefficient, curvature coefficient, and clay content than ANB; (2) experiencing freeze-thaw cycles, ANB exhibits an increasing permeability coefficient, whereas ACB, particularly at a high bentonite content, experiences a decreasing permeability coefficient with additional freeze-thaw cycles. Simultaneously, freeze-thaw effects degrade the compression indices of both ACB and ANB; and (3) increasing the normal stress leads to a rapid reduction in compression coefficients for ANB and ACB, with the rate of decrease gradually slowing down. Under constant normal stress, the compression coefficient ratio (ANB/ACB) decreases with rising bentonite content and increases with the number of freeze-thaw cycles. Additionally, electron microscope scans revealed that the freeze-thaw cycle effect influences the permeability and compressibility of the soil by altering the soil sample's pore structure and particle size.