Suction-Volume Change Indices for Natural and Recompacted Clay Soils

The mechanical response of unsaturated soil is controlled by the two stress state variables of matric suction and net normal stress. Modern geotechnical laboratory devices allow for the direct measurement of unsaturated soil volumetric response under controlled conditions of both stress state variables. The oedometer pressure plate device (OPPD) is one apparatus that can impose suction-induced partial wetting conditions under constant or varying vertical stress conditions while measuring vertical deformations. This study brings together three extensive laboratory investigations of the mechanical response of fine-grained soil specimens to variations in both matric suction and net normal stress, which were conducted using a series of OPPDs located at Arizona State University's Geotechnical Laboratory. The effects of differing soil index properties, sample preparation, and stress path history on the moisture-driven volumetric response is evaluated. A comparison between the suction-volume change indices of reconstituted clay specimens to those of relatively intact clay specimens is also included.