A review of lateritic soils and their use as landfill liners

The role of a landfill liner in the waste management process cannot be overemphasized. They are usually made of clay soils or geosynthetic materials or both with the sole purpose of controlling the migration of leachates into underlying aquifers and soils thereby preventing contamination. The limited availability of clay soils and high cost of geosynthetics have necessitated the search for and use of different locally available materials. Lateritic soils are one of the most commonly used materials for landfill liners in the tropical areas, where they commonly occur. However, a comprehensive review of literature on the utilization of lateritic soils as landfill liners has not been reported. Conducting a systematic review of lateritic soils for landfill liner applications enables an enhanced understanding of their inherent characteristics and appropriateness. This, in turn provides vital insights for the design and construction of effective and economically sustainable waste containment systems. Hence, this paper reviews the nature and characteristics of lateritic soils and assesses their suitability for landfill lining applications through a thorough evaluation of the desirable geotechnical, geological and geochemical properties based on available literature and data. Data on the index and geotechnical characteristics of lateritic soils at two hundred and seventy-eight locations from different countries were collected from literature and assessed based on standard specifications for landfill liners. Furthermore, their leachate attenuation characteristics and improving their suitability for landfill liners through property amendments are presented. The review results indicate that lateritic soils possess suitable engineering properties with some interesting clay mineralogical compositions for lining applications. In addition, the desirable geotechnical properties of lateritic soils can also be improved by blending it with bentonite, fly-ash, sawdust and mine tailings. Although mineralogical transformations occur after permeation with landfill leachates, lateritic soils possess contaminant attenuation characteristics such as low diffusion, good sorption and cation exchange properties that are needed for landfill liner applications.