Abstract: To explore the salt expansion behavior of coarse saline soils containing sulphate under drying, sets of laboratory experiments were conducted to investigate the impact of void ratio, salt content, initial water content and temperature on salt expansion rate. The deformation behavior as water content decreases are the compete of two types of soil-water interactions: shrinkage of soil due to drying, and the swelling of crystallized salts dissolved in pore water. The decreasing rate of water content shows positive correlation with void ratio, temperature and initial water content but negative correlation with the salt content. The test results show that the salt expansion rate of some sample reaches 9%, suggesting that the salt expansion of sulphate saline soil with decreasing water content should not be ignored. It is expected to provide guidance for evaluation on the salt expansion of foundations of residual sulphate saline soil with high salt content in the northwest region.

Key words: coarse particles, sulphate saline soil, water content, descending, salt expansion rate