ABSTRACT
The bulk behaviour of a clay is the overt manifestation of the sum of the interactions of all of the microstructural units (MUs) that comprise the macroscopic skeletal network of the clay. We define the microstructural constitution of a soil to mean a soil that is composed of MUs that combine to form the macroscopic skeletal network of the soil. The mechanical, physical and physico-chemical properties of a clay soil are direct products of: (a) the homogeneity or lack thereof (heterogeneity) of the microstructural constitution and (b) the reactions between MUs themselves and between the MUs and the porewater. The properties and interactions of interest such as hydraulic conductivity, gas penetrability and ion diffusion, transport, shear strength, creep and erodability will be considered in this chapter. Our interest centres around the establishment of meaningful relationships between the microstructural constitution of clays and the aforementioned properties – with particular focus on smectitic clays.
