Sustainability study of the application of geosynthetic clay liners in hostile and aggressive environments

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Wijeyesekera, D.Chitral ; Loh, E. W. K. ; Diman, S.F. ; Alvin, J. ; Zainorabidin, A.B. ; Ciupala, Mihaela Anca (2012)
  • Publisher: Inderscience

This paper discusses the sustainable performance of geosynthetic clay liners (GCLs) which are popularly specified as “leachate retaining” or as “water proofing” membranes in the geo-environmental construction industry. Geosynthetic clay liners (GCLs) are composite matting comprising of bentonite clay with two covering geosynthetics. These are innovative labour saving construction material, developed over the last three decades. The paper outlines the variety of Geosynthetic Clay Liners (GCLs) can be classified essentially into two distinctly different forms viz; (a) air dry (< 8% m/c) with granular or powdered bentonite or (b) bentonite cake factory prehydrated to a moisture content (~40% m/c) beyond its shrinkage limit and vacuum extruded as a clay cake to enhance its sustainable performance. The dominant mineral in bentonite clay is the three-layered (2:1) clay mineral montmorillonite. High quality bentonites need to be used in the GCL manufacture. Sodium montmorillonite has the desired characteristic of high swelling capacity, high cation exchange capacity and the consequently very low hydraulic conductivity, providing the basis for the hydraulic sealing medium in GCLs. These encapsulate the active montmorillonite clay minerals which depend on the water and chemical balance between the sealing element and the surrounding geo environment. Quantitative mineralogical analyses and an assessment of the adsorbed cation regime, diffusion coefficients and clay leachate compatibility must necessarily be an integral part of the site appraisal to ensure acceptable long term sustainability and performance. Factors influencing the desired performance of bentonite in the GCLs placed in difficult construction and hostile chemical environments are discussed in this paper. Accordingly, the performance specifications for GCLs are identified and the appropriateness of enhancing the cation exchange capacity with polymer treatment and the need for factory prehydration of the untreated sodium bentonite is emphasised. The advantage of factory prehydrating the polymer treated bentonite to fluid content beyond its shrinkage limit and subsequently factory processing it to develop laminated clay is to develop a GCL that has enviable sealing characteristics with a greater resistance to geochemical attack and cracking. Since clay liners are buried in the ground as base liners, capping layer or as structural water proofing membrane, they can easily avoid strict quality and performance monitoring being “out of sight, out of mind!”. It is very necessary that barrier design for leachate containment must necessarily be in accordance with legislative requirement Assessment of long term hydraulic conductivities and clay-leachate compatibility assessment is deemed necessary. The derogatory factors affecting the sustainable performance of the bentonite in GCLs placed in difficult construction and hostile chemical environments are discussed. Sustainability concepts incorporated in waste management practice must aim to achieve 100% recycling and fully implement the handling of solid waste in developing countries with relatively lower labour costs.
  • References (32)
    32 references, page 1 of 4

    [1] Wijeyesekera D C., O'Connor, K., and Salmon D E.,(2001). Design and performance of a compacted clay barrier through a landfill, Engineering Geology, vol 60, (1), 295-305

    [2] Egloffstein T.A. (2001). Natural bentonite - influence of the ion exchange and partial desiccation on permeability and self healing capacity of bentonites used in GCLs. Geotextiles and Geomembranes, 19(7), 427-444.

    [3] Vasko, S., Jo, H., Benson, C., Edil, T. & Katsumi, T. (2001). Hydraulic conductivity of partially prehydrated Geosynthetic clay liners permeated with aqueous calcium chloride solutions. In Proceedings of Geosynthetics 2001, Industrial Fabrics Association International, St. Paul, Minnesota, USA, pp. 685-699.

    [4] Shackelford, C., Benson, C., Katsumi, T., Edil, T. & Lin, L. (2000). Evaluating the hydraulic conductivity of GCLs permeated with nonstandard liquids. Geotextiles and Geomembranes, 18(2-4), 133-162

    [5] Petrov, R. and Rowe, R. (1997). Geosynthetic clay liner (GCL) - chemical compatibility by hydraulic conductivity testing and factors impacting its performance. Canadian Geotechnical Journal, 34, 863-885.

    [6] Ruhl, J. & Daniel, D. (1997). Geosynthetic clay liners permeated with chemical solutions and leachates. Journal of Geotechnical and Geoenvironmental Engineering, 123, 369-381.

    [7] Di Emidio, G., Mazzieri, F., Van Impe, W.F. & Van Impe, P.O. (2008). Hydraulic conductivity, free swell and swelling pressure of a dense prehydrated GCL (DPH GCL). In proceeding of the 1st Middle European Conference on Landfill Technology, Budapest, Hungary.

    [8] Mazzieri, F. & Pasqualini, E. (2008). Effect of dry/wet cycles and cation exchange on the permeability of a dence prehydrated GCL. In proceedings of the EuroGeo4. Edinburgh, UK. Paper number 125.

    [9] Katsumi, T., Ishimori, H., Onikata, M. & Fukagawa, R. (2008). Long-term barrier performance of modified bentonite materials against sodium and calcium permeant solutions. Geotextiles and Geomembranes, 26, 14-30.

    [10] Kolstad, D.C., Benson, C.H., Edil, T.B. & Jo, H.Y. (2004). Hydraulic conductivity of a dense prehydrated GCL permeated with aggressive inorganic solutions. Geosynthetics International, 11(3), 233-241.

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