Applicability of Recycled Soil Mixed with Bentonite and Polymer as a Waste Landfill Liner

Abstract

Waste landfill liner has been developed with a variety of materials, but the landfill liner and cover material have not been developed in consideration of the local conditions. In order to build a cost effective municipal solid waste (MSW) landfill site, it is necessary to develop technology that utilizes materials suitable for local characteristics as liner. The purpose of this study is to develop an amended compacted clay liner (CCL) by proportionally mixing construction waste soil called “recycled soil” with small amount bentonite powder as well as polymer powder. Permeability and strength characteristics of recycled soil-bentonite mixture were analyzed through laboratory test and then compare this mixture with characteristics of marine clay-bentonite mixture. The characteristics of strength and permeability were analyzed by applying different mixing ratios with adjustment of polymer and bentonite ratios in consideration of its proportion of bentonite’s weight to improve economic efficiency and increase the strength of recycled soil-bentonite mixture. Finally, the proper mixing ratio of recycled soil-4% bentonite-0.28% polymer mixture was determined considering economical efficiency. The mixture was confirmed to be suitable as lining material based on the results of dry shrinkage test, free swelling test, and soil contamination test. In this study, it is proposed the mixing ratio of recycled soil, bentonite, and polymer as a minimum ratio that satisfies the standard of hydraulic conductivity(1 × 10−7 cm/sec) on the waste management law and unconfined compressive strength (500 kPa) on the specification of construction of waste landfill liner.