Hydraulic behaviour of dune sand-bentonite mixtures under confining stress

Compacted layers of sand-bentonite mixtures have been proposed and used in a variety of geotechnical projects as engineered barriers for the enhancement of impervious landfill liners, cores of zoned earth dams and radioactive waste repository systems. This paper presents a study on the valorization of local materiel such as dune sand from Laghouat region and mine bentonite intended for the realization of liner base layers in the conception of insulation barriers for hazardous waste centers. In the practice we try to get an economical mixture that satisfies the hydraulic and mechanical properties specified by regulation rules. The effect of the bentonite additions on the mixture is reflected by its capability of clogging the matrix pores upon swelling. In order to get an adequate dune sand-bentonite mixture, an investigation on hydraulic and mechanical behaviours is carried out in this study for different mixtures. Using oedometer test, the adequate bentonite addition to the mixture, which satisfies the conditions on permeability, is found to be around 12% to 15%. These results are also confirmed by direct measurement using triaxial cell.