Experimental study on contact angle and pore characteristics of unsaturated loess

Contact angle and pore size are important factors affecting soil wettability, permeability and capillarity. In order to further understand the capillary characteristics and permeability of unsaturated loess, the contact angle test and mercury intrusion test of unsaturated loess were carried out. The relationship between pore size and contact angle was analyzed in details. Moreover, the variation of pore and contact angle with depth was discussed. It is found that the contact angle of loess in the dry state is higher than the contact angle of loess in the natural state; as the depth of the formation increases, the contact angle increases; the contact angle is negatively correlated with the large and medium pore volume, whereas is positively correlated with the micropore volume. Additionally, in the shallow part of the stratum, the contact angle is positively correlated with the small pore volume, while for the deep stratum, the contact angle is negatively correlated with the small pore volume. In unsaturated loess, the content of small pores and micropores is relatively large, while the content of large and medium pores is relatively small.