Effect of Liquid Type on the Hydraulic Characteristic of Compacted Local Geomaterials for Use as Hydraulic Barriers

Abstract

In landfill applications, compacted sand-bentonite mixtures are often used for constructing hydraulic barriers. This paper studies the valorization of local materials containing calcareous sand, tuff obtained from Laghouat region, to associate with bentonite in order to improve their hydraulic characteristics for use as landfill liner material. Firstly, a geotechnical characterization of mixtures chooses from a fixed percentage to 10% bentonite and daren’t percentages of calcareous sand and tuff so that they are complementary to 90% (by not 10%). Thereafter, the hydraulic characteristics study was conducted through free swelling test and the oedometric (Kid, indirect measure) test of all compacted mixtures have been carried out using both permeates by tap water and a landfill leachate in order to simulate long-term conditions. The results showed that the saturated hydraulic conductivity of landfill leachate is relatively lower than the one saturated by tap water. The B10CS20T70 mixture has satisfied the hydraulic conductivity criterion of bottom barriers and relatively stable against chemical attack from leachate (i.e. with water permeated: G(%) = 12.21% and kid from 7.10−9 to 1.83.10−10 < 10−9m/s; with leachate permeated: G(%) = 10.42% and kid from 7.10−9 at 1.44.10−10 < 10−9 m/s). Finally, a comparison between direct measurements of the saturated hydraulic conductivity by triaxial (Kd) test and oedometer test (Kid) in the range of effective stress applied 100–800 kPa led to propose equations of correlations between these two methods. In conclusion, adopted formulation B10CS20T70 perfectly meets the regulatory requirements in force and constitutes an economic product based on available local materials for engineers barriers.