Simultaneous determination of soil-water characteristic and shrinkage curves of consolidated kaolin under continuous and discrete drying procedures

Soil-water characteristic curve (SWCC) and shrinkage curve are essential information required for analyzing the behaviors and properties of unsaturated soils. This study proposes a new method for simultaneous measurement of SWCC and shrinkage curve of a “single” soil specimen. The validation of the method was carried out using kaolin specimens prepared at low levels of consolidation pressures. The changes in void ratio, gravimetric water content, and soil suction of the specimen under continuous or discrete drying procedures were measured using the vernier caliper, the balance, and the osmotic tensiometer, respectively. The results show that the shrinkage curves of all specimens are almost the same regardless of their different initial gravimetric water contents and initial void ratios. However, the obtained gravimetric water content SWCC (SWCC-) in the lower suction range was related to the initial gravimetric water content of the specimen. In contrast, the degree of saturation SWCC (SWCC-) of all specimens were almost the same and the air-entry values of different specimens were shown to be quite close. The results indicate that continuous drying procedures would not cause obvious differences in the measured SWCC as well as shrinkage curve compared with the discrete drying procedures. The relationship between the void ratio and soil suction of the specimens shows that the void ratio has a rapid decrease in the lower suction range and reaches the minimum value when the soil suction is about 300 kPa. The proposed method would shorten the time for obtaining the properties of unsaturated soils and would benefit the related analyses.