Air Volume Change Measurement in Unsaturated Soil Testing Using a Digital Pressure-Volume Controller
One of the challenges associated with the testing of unsaturated soils is the measurement of air volume change induced by stress changes. This paper reports the results of an evaluation of a digital pressure-volume controller as an air volume change indicator. Effects of temperature, confined volume, and precompression of the measurement medium on the p-V characteristics and the device response were determined. The device was also used to measure air volume changes of unsaturated soil specimens undergoing isotropic consolidation and axial loading in constant water content tests in a triaxial cell. The results show that the controller performs satisfactorily as an air volume change measurement device. It also permits measurement of air volume change simultaneously with the implementation of the axis-translation technique, making it a versatile device in the testing of unsaturated soils.