Cyclic Swelling Behavior of Clays

This paper investigates the effect of cyclic wetting and drying on the expansive characteristics of clays. For this purpose, six expansive soils were obtained from various locations in Irbid (a city in northern Jordan). After each cycle, the swell potential and swell pressure were measured. Additionally, the soil microstructure before and after cyclic swelling was investigated. The experimental data indicated that upon repeated wetting and drying, the soils show sign of fatigue after every cycle resulting in decreased swelling ability. Furthermore, it was noted that the first cycle causes the most reduction in swelling potential. As the number of cycles increases, additional reduction was observed until an equilibrium state is reached. For the six utilized soils, the equilibrium cycle ranged between 4 and 5. Scanning electron micrographs clearly showed a continuous rearrangement of particles during cyclic wetting and drying. This led to lower structural element orientation due to the integration of structure along the bedding, resulting in correspondingly lower water absorption thus reducing swelling ability.