Freezing-Thawing Effect on Saturated Clay Microstructure

The mechanical behavior of clays is altered when it is exposed to freezing-thawing cycles. Freezing-thawing results in volume change increasing the clay permeability. While there are numerous macroscale experiments to prove the evolution of the mechanical behavior of clay, limited amount of microscale experiments exist to evaluate the microfabric changes in clay. In this study, six specimens were subjected to temperature changes using a thermo-mechanical triaxial apparatus under single drainage and double drainage boundary conditions to mimic the natural drainage conditions of clay deposits. The specimens were then freeze-dried to preserve their microstructure before and after thermal paths. Moreover, the specific surface area of each specimen was approximated using N2-gas sorption method and BET (Brunauer-Emmett-Teller) analysis. Finally, macro-scale behavior of frozen-thawed clays was justified by the evolution of microstructure. Experimental results suggest that access to free water has a significant impact on the thermal behavior of clays during freezing and thawing.