An experimental investigation of unsaturated clay: volume change and microstructural considerations

Predicting the behaviour of unsaturated soils, and in particular compacted high plasticity clays, is a pre-requisite for the safe and reliable functioning of civil infrastructure. However, the complex behaviour of high plasticity clayey soils subjected to changes in their hydraulic and stress states are not well understood in engineering design. This thesis-by-publication focuses on an experimental investigation of the volumetric and microstructural behaviour of compacted clays. The following significant contributions to an understanding of unsaturated soil behaviour have been made through the journal articles that comprise this thesis-by-publication: Identification of the microstructure properties that are common between compacted and reconstituted soils. ; Proposal of a new method for delineating micro and macro components of the void ratio. ; Identification of the water retention behaviours that are common between compacted and reconstituted soils. ; Proposal of a new approach to unsaturated soil testing using the axis-translation technique, where the degree of saturation is controlled directly.