Modelling the shrinkage curve of soil clay pastes

The shrinkage properties of soil require an understanding of the volumetric changes to swelling clays, the presence of non-swelling minerals like silt and sand and the soil volume occupied by cracks and other voids. It is natural to consider first the matrix of clay particles only. The objective of this work is the further development of a basic model of the shrinkage curve of a soil clay based on its microstructure. The specific goals include developments of a relation between the saturation degree and pore-size distribution; a physical condition determining the shrinkage limit of a soil clay paste. The points of the basic model (the major concepts, definitions, assumptions, simple formulas and results) that are relevant to these goals are preliminarily briefly summarized. Application of the points supplemented by the above developments allows one: to reduce the number of independent macroparameters of clay paste that were introduced in the basic model; to express the residual water content, shrinkage limit and shrinkage curve of clay paste through the reduced number of its macroparameters; to show additional interconnection between micro- and macroparameters of the clay paste microstructure, besides those indicated in the basic model. Comparison between model estimates and relevant available data on characteristic points of the shrinkage curve of soil clay pastes gives arguments in favour of the basic model supplemented here that enables one to predict the total shrinkage curve of a clay paste, including the residual water content, shrinkage and liquid limits. (C) 2002 Elsevier Science B.V. All rights reserved.