Swelling of unsaturated GMZ07 bentonite at different temperatures.

A series of wetting tests on unsaturated compacted GMZ07 sodium bentonite, taken from the Gaomiaozi area, Inner Mongolia, China, was performed to investigate the swelling characteristics of the GMZ07 sodium bentonite at temperatures of 5, 20, 60 and 75 °C. The influences of temperature and initial dry density on swelling deformation and swelling pressure were studied by performing a series of constant-stress and constant-volume tests under the wetting condition. The test results showed that the swelling deformation and swelling pressure due to saturation decreased slightly with increasing temperature. A linear relationship was present between the vertical pressure and corresponding saturated void ratio in the semi-logarithmic coordinate at a given temperature; this line is referred to as a state line. Swelling or collapse due to saturation was found to be dependent on the relative location of the initial state between the state line and initial state. The void ratios after saturation at different initial dry densities were close at the same temperature and vertical pressure. [ABSTRACT FROM AUTHOR]