Twin-cell stress path apparatus for testing unsaturated soils.

Determination of specific volume changes of unsaturated soils remains a challenging issue in soil testing for a number of reasons. Various attempts have been made over the years to improve the techniques of sample volume change measurement. This technical note reports the benefit of using a fully automated twin-cell stress path apparatus for measuring sample volume change and hence determining the specific volume. The system requires calibration for apparent volume change due to expansion of plastic tubes and connections. The results have shown excellent repeatability of the apparent volume change during the loading and unloading process.