Geotechnical Characterization Of Geomaterial Blends With Bentonite Of Maghnia For Use As Landfill Liners

Compacted soil-bentonite mixtures are often chosen as a liner material in landfill applications. Saturated hydraulic conductivity of ksat ≤10-9 m/s and shear strength (friction angle: >25°) are required in the design of engineered barriers. The effects of the bentonite additions are reflected in lower water permeability, and relatively acceptable shear strength. The first step in this study consists in presenting the results of the physical and chemical tests of the characteristics of tuff, calcareous sand and bentonite used for the experiment, which are available local materials in Laghouat and Maghnia (Tlemcen) regions respectively. After that, a study of the hydraulic characteristics of the mixtures containing 10% bentonite +% calcareous sand+% tuff was conducted through free swelling test and the oedometric test. A mechanical study of the characteristics of these mixtures compacted with the optimum Normal Proctor condition was carried out by means of direct shear test and unconfined compression test. Finally, results show that a mixture of 10% bentonite, 20% calcareous sand and 70% tuff meets the requirements of hydraulic conductivity and shear strength. The mixture represents a readily material available alternative for the design of barrier liners.