ABSTRACT
Granular bentonite base clay liners are widely used in landfills as hydraulic barrier because of their low hydraulic conductivity and self-sealing ability. Recent studies reported that the hydraulic conductivity of Granular bentonite has significantly increased due to the presence of different inorganic cations (i.e., Na+, K+, and Ca++), which causes the mechanical instability. This subsequently results in ground water contamination due to leachate migration from the liners. To address this problem, a composite mixture of granular bentonite and hydroxy methyl cellulose at different proportions (2-10% HMC) has been tested in the laboratory under extreme chemical (0.50M CaCl2) and mechanical (20-100kPa) loadings. The performance of different mixtures is evaluated in terms of hydraulic conductivity and volume change. It is found that the mixture of granular bentonite and 10% hydroxy methyl cellulose has attained lower hydraulic conductivity (10-11-10-9m/s) than the critical hydraulic conductivity (10-9m/s) under extreme chemical and mechanical loadings.
