Coupled Chemical and Liquid Fluxes in Earthen Materials

The potential importance of coupled chemical and liquid fluxes in earthen materials has been recognized and investigated in the geologic and soil science disciplines for several decades. The mechanisms involved cause a family of coupled transport phenomena that are commonly referred to as osmotic or membrane phenomena. Recently these phenomena have attracted the interest of geotechnical researchers because they appear to provide mechanisms for enhancing the capability of clay barriers to impede the migration of contaminants. To facilitate geotechnical interest in these phenomena, this paper presents a brief review of the pioneering field studies of membrane phenomena in geologic systems, a summary of the pertinent coupled flow theory developed to date, and a synthesis of the experimental evidence obtained in laboratory studies during the last five decades.