Thermally induced volume change behavior of sand-clay mixtures

The deformation and strength of soils change significantly under thermal loading, which affects the safety and stability of thermal-related geotechnical infrastructures. Although laboratory tests have been performed on pure clay or sand, few studies were conducted on binary sand-clay mixtures. To enhance the understanding of the mechanisms for thermally induced volume change behavior of sand containing plastic fines, a series of drained heating tests and temperature-controlled isotropic consolidation tests were conducted. The results of the drained heating test demonstrate that the sand-clay mixtures generally exhibit plastic volumetric contraction deformation at temperatures ranging from 20 to 60 degrees C. The thermal volumetric contraction increases with increase in stress level or fine content. With isotropic consolidation tests, it was found that the compression curves gradually moved downward with an increase in temperature. The compression and swelling indexes change slightly with temperature variation, which can be considered independent of temperature. The yield stress of sand-clay mixtures decreases with increase in temperature, and the thermal softening phenomenon becomes more obvious with an increase in fine content. The proposed equation for yield stress accurately predicted the temperature- and fines-dependent behavior of sand-clay mixtures.

Automated summary

The deformation and strength of soil are significantly influenced by thermal loading, especially in thermal-related geotechnical infrastructures. This study investigates the behavior of sand-clay mixtures under thermal loading and found that the mixtures exhibit plastic volumetric contraction deformation and decrease in yield stress with increasing temperature.