Impact of bentonite form on the thermal evolution of the hydraulic conductivity of geosynthetic clay liners

Several field observations have confirmed that engineered liner systems of municipal solid waste landfills could be subjected to temperatures up to 60°C over the course of their lifetime. These elevated temperatures are reportedly due to ongoing bio-degradation of the waste and, as reported by several authors, can have a significant impact on the service life of the geosynthetic components of engineered lining systems in addition to the already established effects on landfill processes. The preliminary study reported here aimed to experimentally assess the effect of temperature on the hydraulic conductivity of geosynthetic clay liners containing different forms (i.e. granular and powder) of sodium bentonite. The experimental programme involved conducting constant-head hydraulic conductivity tests using a modified Rowe cell capable of withstanding temperatures up to 60°C. A theoretical interpretation of the observed test results reveals that the initial microstructure of the bentonite core and its evolution under a thermo-mechanical effect could control the thermal evolution of geosynthetic clay liners' hydraulic conductivity.