Hydraulic Conductivity of GCLs Permeated With Inorganic Chemical Solutions

Abstract

The free swell test, the fluid loss test, and the MFL test were performed for three bentonites with distilled deionized water (DDIW), NaCl, CaCl 2, and LaCl3 solutions under different pressures in order to investigate the influence of chemical solutions and effective stress on hydraulic properties. In solutions with low cation concentration, the free swell index exhibits an increasing trend with increasing concentration before the diffused double layer fully collapsed at higher concentration. Decrease of void ratio, increase of hydraulic conductivity with increasing cation concentration in MFL test is assumed to be due to the pore characteristics of bentonite in solutions. Increase of hydraulic conductivity and decrease of void ratio resulting from increasing cation valence and concentration could be identified. The same slopes of linear relations between hydraulic conductivity and effective pressure on a log k-log p plot indicates that varying the cation solution changes hydraulic conductivity, but variation does not change the slope of log k-log p relationships. From the results of three index tests for a bentonite with real-soil-solutions extracted from sub soils and cover soils of GCL placed at test site, the MFL test gives useful and consistent information about the hydraulic behavior of bentonite.