Wetting-induced volume changes in compacted silty clays and high-plasticity clays

Abstract

Wetting-induced deformations of compacted fine-grained soils are of particular interest in earthworks engineering, where embankment design needs to take into account potential future water-content variations. The influence of compaction rate on swelling potential and, more generally, wetting-induced deformations are analyzed in this paper on the basis of an original physical microstructural model. The interpretation of macroscopic experimental results obtained on a high-plasticity clay and a silty clay shows that the model enables quantitative description of intra- and inter-aggregate pore volume changes due to wetting. Using this approach, a fundamental difference was observed between the high-plasticity clay and the silty clay in wetting tests under vertical stress: tests performed on the high-plasticity clay can be analyzed using a microstructural model, whereas this model is not relevant for the analysis of silty clay behaviour, which is better interpreted in the framework of a conventional elastoplastic model. The interpretations were compared to microstructure observations, which support the main tendencies deduced from the model.