Prediction of loess soil-water characteristic curve by mercury intrusion porosimetry

Mercury intrusion porosimetry (MIP) is a simple and fast way to obtain the pore distribution of soil and can be used to estimate the soil-water characteristic curve (SWCC). In previous studies, soil was assumed to be a perfect wettability material, and the contact angle (CA) of the soil-water interface was taken as zero in the SWCC prediction method. However, the CA has proved to be much greater than zero even for hydrophilic soils according to some soil wettability experiments, and it has a significant effect on predicting the SWCC. In this research, a method for predicting the SWCC by MIP, which takes the CA as a fitting coefficient, is proposed. The pore size distribution curves are measured by MIP, and the SWCCs of two loess soils are measured by pressure plate and filter paper tests. When the CA is taken as 70° and 50° for the wetting and drying process, respectively, the SWCCs predicted by the pore size distribution curves agree well with the measured SWCCs. The predicted suction range of the proposed method is 0–105 kPa. The consistency of the results suggests that utilizing the MIP test to predict the SWCC with a proper CA is effective for loess.