Effect of permeant liquid on the swell volume and permeability of geosynthetic clay liners

Anekpong Thammathiwat and Weeraya Chim-oye

Nowadays geosynthetic clay liners (GCLs) are frequently used as hydraulic barriers from leachate in liner for waste containment facilities. This research aims to study (1) the effect of cation valence by using monovalent (LiCl, NaCl and KCl), divalent (CaCl2, MgCl2 and CuCl2) and trivalent (FeCl3) salt solutions, (2) the effect of concentration of CaCl2 and (3) effect of pH on swelling volume and permeability coefficient. The consolidation test, the indirect method, was used to find the permeability coefficient. At similar concentrations the swell volume was larger with monovalent cation solutions than with divalent and trivalent cation solutions. With various concentrations, swell volumes decreased with the increasing of concentration for all solutions. GCLs permeated with solutions containing divalent or trivalent cations had a higher permeability coefficient than GCLs permeated with monovalent or distilled water. The permeability coefficient of GCLs decreased with the increasing of concentration. Moreover, it was found that pH only influenced the swell volume and permeability coefficient when pH was very low (pH=2) or very high (pH=12).