A double layer theory for mixed ion systems as applied to the moisture content of clays under restraint

Abstract

A double layer equation (after Gouy) for heterovalent ionic systems is applied to the thickness of the water films associated with the ionic double layer of clay particles. The equation is tested against a Ca/Na/Cl montmorillonite described by Smiles and Rosenthal (1968) in terms of moisture content versus pressure restraint. The equation reduces to simpler exact formulae for the case of unconstrained clays and gives useful approximations for the situations of small interactions and of large interactions which cover most situations to be encountered in soil systems. The restrictions of the application of the double layer model to swelling clay systems are considered.