Water retention characteristics of swelling clays in different compaction states

The soil water retention (SWR) characteristics of the clays play an important role in controlling their engineering behaviour, particularly, in the unsaturated state. Although, researchers have attempted to understand the water retention characteristics of the clays in their reconstituted or remoulded state, such studies are rare for the clays in their intact state. In this context, it becomes important to understand the influence of initial state of compaction, which would create different pore- and fabric- structure (viz., microstructure), on the water retention characteristics of the clays. With this in view, SWR behaviour was determined experimentally for the swelling clays (dried from different compaction states, viz., intact, reconstituted and remoulded) by employing Dewpoint Potentiameter (WP4C®). The changes in the pore-size distribution of the clays at different stages of drying cycle were also studied by employing the Mercury Intrusion Porosimetry. The study reveals that the SWR curves for the intact and reconstituted specimens of the clays converge beyond a certain stage of drying. Also, a critical analysis of changes in the pore structure of the swelling clay specimens, during drying, indicates that the progressively deforming pore structure play an important role in controlling its water retention characteristics to a great extent.