High pressure triaxial cell for thermal volume change measurements of unsaturated soils

This study focuses on a new experimental approach to characterize the thermal volume change of unsaturated soils under different stress states. Specifically, a thermal triaxial cell was constructed with suction control using the axis translation technique, saturation control using a flow pump, cell pressure control using a high pressure flow pump, and a metal cell to permit application of net mean stresses up to 10 MPa. The cell was constructed to measure the thermal volume change of unsaturated soils under high degrees of saturation (continuous water phase) while precisely tracking the total soil volume and pore water outflow/inflow volumes, in addition to measuring the impacts of suction and temperature on preconsolidation stress. The thermal triaxial cell is also capable of applying anisotropic stress states, with the axial stress controlled using a pneumatic Bellofram piston. This paper presents the thermo-mechanical calibration data along with the results from a test on an unsaturated silt specimen. The thermal volume change of the specimen up to a temperature of 40 degrees C was consistent with results from the literature for normally consolidated conditions.