Evaluation of the freezing–thawing effect in sand–silt mixtures using elastic waves and electrical resistivity

The purpose of this study is to investigate the effects of the freezing–thawing process on soils using elastic waves and electrical resistivity. Sand–silt mixtures with different silt fractions of 0%, 10%, 20%, 30%, 40%, 60%, 80%, and 100% weight at a fixed degree of saturation of 40% are placed in a nylon freezing cell. The temperature of the sand–silt mixtures decreases from 20 °C to − 13.5 °C during freezing and increases from − 13.5 °C to 20 °C during thawing. Bender elements and piezo disk elements are used to continuously measure shear and compressional waves, respectively, during freezing and thawing. Four circular electrodes made of stainless steel are used to measure electrical resistivity. For the temperature measurement, a thermocouple is inserted into the specimen. The shear and compressional wave velocities as well as electrical resistivity dramatically change near 0 °C during freezing and thawing for all sand–silt mixtures. After one cycle of freezing–thawing, the elastic wave velocities decrease and the electrical resistivity increases due to the fabric change of the specimens. During the thawing process, the electrical resistivity displays hysteresis behaviors (not elastic wave velocities) from − 3 °C to 0 °C. This study demonstrates that elastic waves and electrical resistivity may effectively capture the property changes of the sand–silt mixtures during freezing–thawing.