Soil-water characteristics and pore-size distribution of lateritic clay

The pressure plate method, filter paper method and vapor equilibrium technique with saturated salt solution and mercury intrusion porosimetry tests on Guilin lateritic clay are used to investigate the soil-water characteristics and pore-size distribution of undisturbed and compacted specimens in full suction range. The test results show that the undisturbed specimen has lower water content and saturation degree than the compacted one in the suction ranging from 0 kPa to 10 MPa because of the development of internal crack of undisturbed specimen with the increasing suction. When the suction is higher than 10 MPa, the soil-water characteristic curves (SWCC) coincide with each other. In the transition zone, the SWCCs of the undisturbed and compacted specimens are different from the typical ones. The undisturbed natural specimens exhibit a unimodal pore-size distribution, and the compacted ones usually have a double-porosity microstructure. The stability of shrinkage of the undisturbed natural specimen is larger than that of the compacted one. The compacted specimens with different dry densities also have the same pore-size distribution between particles, while the inter-aggregate pore distribution differ between the compacted specimens with different dry densities. It explains that when it is expressed by the relation between suction and water content, the SWCC is independent of dry density in the high suction range. When it is expressed by the relation between suction and saturation degree, the SWCC with high dry density is higher than that with the small one.