Abstract
Increased awareness of the structural damages associated with expansive soils has led to more attention being focused on different aspects of their characteristics and behaviour. The majority of volume change testing of expansive soils has been performed under one-dimensional loading conditions in the oedometer. However, due to differences between laboratory test constraints and field conditions the amount of volume changes measured in various oedometer-testing methods may differ dramatically from heaves actually realized in the field. Recent advances in testing techniques enable setups that can perform suction control testing of unsaturated soils. In this study, hydraulic stress path testing system is used to investigate the volumetric strain of expansive soil specimens at a range of suction levels. The system control of suction relies on axis-translation technique in which the desired suction value is obtained through the control of air pressure applied from the top of the sample and pore water pressure introduced through high air entry porous ceramic disc from the bottom. Slurry consolidated specimens prepared from natural clay of Tabuk region, Northwest of Saudi Arabia, is investigated for different values of confining pressures. The trends of volume change related to different suction values are observed and compared for the selected radial stresses. The parameters influencing the accuracy and reliability of the setup are examined and discussed.