Abstract: As a major clay mineral in swelling soil, montmorillonite has important influence on swelling-shrinkage properties and developing fissures of swelling soil. Desiccation tests were conducted under 40 ℃ on initially saturated montmorillonite-silica sand mixture slurry to investigate the effects of montmorillonite content on shrinkage and cracking characteristics. Water loss and surface crack evolution were monitored during the whole drying period while the critical moisture content and surface crack ratio δ_S were obtained with computer software. The results showed that during drying period, the process of water loss showed three obvious phases: the evaporation phase at constant speed, the decline phase and the residual phase. And cracks on the surface of samples mostly developed in the first phase. The final surface crack ratio δ_SF and the initial moisture content w_I at which the cracks start were significantly influenced by the content of montmorillonite showing trend of increasing with the growth of the content of montmorillonite. But the final moisture content w_F at which the cracks end were different, yet, the difference Δw between w_I and w_F is positively related to the content of montmorillonite.

Key words: montmorillonite, drying curve, crack, critical moisture content, quantitative analysis