Analysis of the process of swelling and shrinkage of clay soils subjected to wetting-drying cycles

The results highlight a difference in swell-shrink behaviour between the two studied soils and stress the importance of the presence and the nature of clay minerals and the microstructure of the soil on the swelling and shrinkage phenomenon as well as on the accompanying microstructural transformations. They also reveal the role played by carbonates, cementation and initial conditions on intact or remoulded soils during moisture changes. Finally, the influence on the hydromechanical behaviour of wetting-drying cycles was analysed. The experimental results show that during the successive wetting-drying cycles, while the soil samples show an increase in the cumulative swelling deformation, a stabilization of swell strain of each cycle is reached at the end of the third or fourth cycle. These results are compatible with a reorganization of the microstructure as highlighted by the microstructural (SEM, porosimetry) analysis.