• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.5-15
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• 2011

Conventional designs of landfill covers use geosynthetics such as geomembrane and GCL, and clay liners to lower the permeability of final covers of landfill sites. However, differential settlement and the variation of temperature or humidity in landfill sites cause the development of cracks or structural damage inside the final cover. This study examined the application of a Self Recovering Sustainable Liner (SRSL) as an alternative landfill final cover material. SRSL consists of double layers, which have chemicals, can generate precipitates filling the pores of the layers by chemical reaction. The interface material forms an impermeable layer and in case of internal cracks, the reactants of the two layers migrate towards the crack and heal it by forming another liner. In this study the applicability of SRSL material for landfill final cover was examined by performing flexible wall permeameter tests to prove that the hydraulic conductivity is lower than the regulations and unconfined compression tests to judge whether the strength satisfies the restriction for the landfill final cover. Furthermore, the environmental impacts on the permeability and strength were evaluated. The experimental results show that the SRSL has lower hydraulic conductivity and higher strength than the regulations and is little influenced by climatic changes such as wet/dry or freeze/thaw process.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.45-56
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• 2006

Recently, the more potential waste sites are being required as increasing the demand of better human life. But the construction of waste disposals has many restrictions because of lack of good quality clay and high cost of liners. So, in this study, we studied the liner materials to develop more cheaper soil liner that can be satisfied the environmental criterion for the coefficient of permeability and shear strength. A series of compaction test and triaxial (consolidation, permeability, and shear) tests were performed to obtain the optimized weight ratio of Bentonite-Soil mixture (B/S) including the least amount of bentonite. A series of soil tests were performed to acquire the appropriate weathered granite soil-bentonite mixture that is satisfied the environmental criterion of soil liner($k=1{\times}10^{-7}cm/sec$). At first, weathered granite soils were classified with four different particle-size soils, and B/S ratio was increased as 5% step for each particle-size. The test results showed that in case of weathered granite soil passing through No. 100 sieve, B/S=15% satisfied the soil liner criterion. The measured coefficient of permeability and the Chapuis's two equations were also compared. And a predicting equation for the coefficient of permeability was suggested, which is suitable for the mixture soil with the B/S ratio used in this study. The optimal weight ratio for the mixture soils used in this study was 15% in the both cases of permeability and shear strength.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.329-336
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• 2006

Iron manufacturing process involves production of various by-product including slag, sludge, sintering and EAF(Electric Arc furnace dust). Some of the by-products such as EAF and sintering dust are disposed of as waste due to their high heavy metal contents. It has been notice for many years that the EAF dust also contain about 65% of Fe(0) and Fe(II) and then the possible utilization of the iron. One possibility is to apply the EAF as a lining material in conjunction with clay or HDPE liners, in waste landfill. The probable reaction between the leachate containing toxic elements such as TCE, PCE dioxine and $Cr^{6+}$ is reduction of the toxic materials in corresponding to the oxidation of the reduced iron and therefore diminishing the toxicity of the leachate. It is, however, prerequisite to evaluate the leaching characteristics of the EAF dust before application. Amelioration of the leachate would be archived only when the level of toxic elements in the treated leachate is less than that of in the untreated leachate. Several leaching techniques were selected to cover different conditions and variable environments including time, pH and contact method. The testing methods include availability test, pH-stat test and continuous column test. Cr and Zn are potentially leachable elements among the trace metals. The pH of the EAF dust is highly alkaline, recording around 12 and Zn is unlikely to be leached under the condition. On the contrary Cr is more leachable under alkaline environment. However, the released Cr should be reduced to $Cr^{3+}$ and then removed as $Cr(OH)_3$. Removal of the Cr is observed in the column test and further study on the specific reaction of Cr and EAF dust is underway.