Abstract: The influence of moisture variation induced by the environmental change on subgrade soils, especially on the lime-treated expansive soils, has increasingly received attentions in the engineering practices. However, the contact pressures applied on the subgrade soils induced by the super structures are generally ignored in the evaluation of the wetting and dissecting cycles on the expansive soil performances. An innovative device that can provide constant axial pressure and lateral restraint, as well as precisely control the variation of moisture content of soil samples, was used in testing of the wetting and dissecting process of lime-treated expansive soil samples. In addition, the conventional method that dries sample in the air and wets sample by springing water were also utilized for comparative study. The GDS dynamic triaxial test equipment was used to test the accumulative axial strain of the samples that experienced different times of wetting and dissecting cycles. It is observed that, under the axial pressure and lateral restraint provided by this innovative device can effectively reduce the damage on samples induced by wetting and dissecting cycles. The results show that the stress state of subgrade soil cannot be ignored when studying the impact of wetting and dissecting cycles.

Key words: lime-treated expansive soils, wetting and dissecting cycles, axial stress, accumulative axial stain