ABSTRACT
The material used to cover landfills is an important factor both during their lifetime and upon their closure. Different procedures have been studied to reduce the permeability of landfill covers in efforts to enhance recovery of the gases produced by waste decomposition and to reduce the amount of leachate produced by rainwater infiltration. Among these, the method of mixing small quantities of bentonite in the cover soil has been shown to be a technically and economically feasible solution. Not only does coverage with this mixture reduce permeability, it also prevents the formation of cracks from shrinkage during the drying process. To ascertain the ideal percentage of a special sodium bentonite developed for use in soil, we designed a device incorporating a tensiometer to monitor the suction, moisture and temperature of soil samples and to provide characteristic curves for the samples tested. This paper presents details of this device and the differences in behavior of the landfill cover in function of the percentage of bentonite added to the cover material. The results indicate the efficacy of using bentonite mixtures and of the device developed to study them.
