Cementation of sand due to salt precipitation in drying process

Salt in soil can cause cementation effect and increase the shear strength and stiffness of soil during the drying process. In this paper, an experimental study is presented to explore the strength, stiffness, and particle level structure of a salt-cemented sand at the dry state. Unconfined compression tests were carried out on sands with various amounts of precipitated dry salt. Scanning electron microscopic and elemental analysis were also conducted. The study shows that the strength and stiffness of sand can increase significantly with salt content. The strength versus salt content curve displays a convex shape, instead of a concave shape as found in cemented or biocemented sands. This implies that the effect of dry salt on soil strength is strong at low levels of salt content. The microscopic and elemental analysis evidences that salt tends to precipitate at particle contacts and form bridges between particles at relatively low salt content. The results presented in the paper may explain why even small amount of salt can lead to an overestimation of soil strength.