Effect of biopolymers on permeability of sand-bentonite mixtures

Application of biopolymer-modified geomaterials in waste disposal practices is gaining wide acceptance due to their superior tensile characteristics and improved crack resistance. Permeability is an important design parameter which determines the suitability of a material as a liner for construction of engineered landfills. Given this, the permeability characteristics of sand-bentonite mixtures amended with biopolymers was studied using a modified-falling head permeability apparatus under an accelerated gravity environment. Both distilled water and synthetic leachate were utilized as permeant liquid to assess the role of biopolymer amendment on the permeation behavior of sand-bentonite mixtures. Experimental results indicate that addition of biopolymers causes aggregation of the clay platelets, which in turn enhances the permeation behavior of the biopolymer-modified sand-bentonite mixtures. These mixtures meet the regulatory requirement of the liner.