Barrier performance of the zeolite-amended bentonite liners, which were developed as an alternative to a bentonite sealing component of geosynthetic clay liners (GCLs) to contain radioactively contaminated municipal solid waste generated by the Fukushima nuclear disaster, was evaluated by per-forming a series of hydraulic conductivity tests. Effects of calcium ions in the permeant on hydraulic bar-rier and cesium (Cs) sorption performances were evaluated for two different types of liners; zeolite-bentonite mixture and zeolite-bentonite composite liners. The composite liners maintained lower hydrau-lic conductivity values than the zeolite-bentonite mixture and the single bentonite liners, due to calcium exchange by the zeolite in first wetting process. Cs sorption performance was greatly improved by the ze-olite, regardless of the ways of zeolite amendment. It was proved that composite liners of the bentonite overlaid by the zeolite were more suitable for the interlayer of the GCLs for containment of radioactively contaminated waste.
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