Column experiments to investigate the thermo-hydro-mechanical-chemical behaviour of sensitive marine clay subgrade stabilized with lime under daily thermal cycles

ABSTRACT: To understand their evolution and interaction in lime-treated sensitive marine clay when exposed to daily thermal cycles, the occurring coupled thermal (T), hydraulic (H), mechanical (M), chemical (C) processes were studied. Two columns in which treated clay was placed, compacted, and monitored for 28 days were prepared and equipped with various sensors placed at different heights to observe the evolution of the coupled processes. A heating blanket through which daily thermal cycles were applied to the soil was placed at the top of one of the columns while no heating blanket was placed on the other columns, serving as a control. Eight additional columns with compacted treated clay were prepared from which samples for testing were obtained from the top and bottom to understand the evolution of the properties after 1, 3, 7 and 28 days. To four of the eight columns, thermal cycles were applied while no thermal cycles were applied to the other four. From the results obtained, it was observed that daily thermal cycles significantly affect the chemical (e.g., lime hydration), mechanical (e.g., strength, deformation), hydraulic (e.g., hydraulic conductivity, suction) and thermal (e.g., thermal conductivity, temperature) properties of treated sensitive marine clay. As a result of lime hydration, the mechanical properties of the clay were seen to have improved tremendously, however, application of the daily thermal cycles were seen to contribute significantly to the improved properties due to higher curing temperatures which increased the kinetics of the chemical reactions. In addition, suction was observed as an influencing factor in the development of the mechanical properties. The results presented in the manuscript on the effects of daily thermal cycles on the THMC properties or behavior of lime treated sensitive marine clay subgrade would thus, contribute to cost-effective design and maintenance of pavement structures constructed on sensitive marine clay soils.