Physicochemical characteristics of Sepiolite and Vermiculite clay soils as landfill clay liners

The liners are the principal components of solid waste landfills which have the main role in controlling the spread of pollution through the landfills. The high cost of artificial materials and their un-usability in large projects for preventing leaks is a major concern that has led to more attention to natural liner materials with low permeability and effective adsorption and stabilization condition. Clay minerals have a high capacity to adsorb heavy metals due to their high specific adsorption levels and bonding sites with numerous negative charges. Along with absorption properties, clay soils should have suitable hydraulic and geotechnical properties as landfill liners. Therefore, this study aimed to evaluate the efficiency of 5 types of soil (vermiculite clay, sepiolite clay, silty soil, silt+clay mixtures as 90% silt and 10% clay) as clay liner. The chemical, physical and mechanical properties of the study soils were evaluated to address the quality of soils as a landfill liner. The results showed that in terms of environmental quality (pollutant adsorption), soils containing sepiolite clay had a better adsorption capacity to adsorb cations rather than vermiculite clay soils. From a physical and mechanical point of view, soils containing sepiolite clay compared to vermiculite clay soil revealed a variety of landfill liner characteristics in terms of strength, permeability, and plasticity properties, respectively. Based on the technical and economic perspective, the silt and sepiolite mixtures supply good features which may justify their potential use as a liner material in solid waste landfills.