Geosynthetic clay liners

Bouazza, Abdelmalek

doi:10.1016/s0266-1144(01)00025-5

Cited by 270 publications

(111 citation statements)

References 29 publications

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“…Geosynthetic Clay Liners (GCLs) consisting of a thin layer of bentonite sandwiched between two geotextiles or glued to a geomembrane are increasingly used as hydraulic barriers in landfill covers and liners. The GCLs that do not include a geomembrane have hydraulic conductivity on the order of 10 À11 m/s when permeated with deionized water or dilute aqueous solutions, owing to the low permeability properties of Na-montmorillonite, the main component of common bentonites (Bouazza, 2002). Unfortunately, the hydraulic conductivity of GCLs can be increased drastically by inorganic permeants that are aggressive to Na-montmorillonite, e.g.…”

Section: Introductionmentioning

confidence: 99%

Diffusion of Calcium Chloride in a Modified Bentonite: Impact on Osmotic Efficiency and Hydraulic Conductivity

Mazzieri

Emidio

Impe

2010

Clays and clay miner.

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Abstract-Chemically modified bentonites are being developed with the aim of preserving low hydraulic conductivity in the presence of potentially aggressive permeants in pollutant-containment applications. 'Multiswellable' bentonite (MSB) has been obtained by treating standard sodium bentonite with propylene carbonate. Research on the engineering properties of MSB has focused mainly on permeability and chemical compatibility. Solute diffusion and membrane behavior in MSB have not yet been investigated. A combined chemico-osmotic/diffusion test was performed on a MSB specimen using a 5 mM CaCl 2 solution. Permeability with distilled water and with the 5 mM CaCl 2 solution was measured prior to and after the chemico-osmotic/diffusion tests. The material exhibited time-dependent membrane behavior with a peak osmotic efficiency value (o) of 0.172 that gradually shifted to zero upon breakthrough of calcium ions. Effective diffusion coefficients of calcium and chloride ions were in the range commonly described for untreated bentonite at similar porosities. After the chemico-osmotic/diffusion stage and permeation with 5 mM CaCl 2 , the hydraulic conductivity of MSB increased from 1.1610 À11 m/s to 7.0 610 À11 m/s. The MSB was apparently converted into a calcium-exchanged bentonite at the end of the test. Prehydration and subsequent permeation might have contributed to elution of the organic additive from the clay. Further investigation is recommended to clarify the effect of prehydration on the hydraulic performance of MSB in the presence of potentially aggressive permeants.

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Section: Introductionmentioning

confidence: 99%

Diffusion of Calcium Chloride in a Modified Bentonite: Impact on Osmotic Efficiency and Hydraulic Conductivity

Mazzieri

Emidio

Impe

2010

Clays and clay miner.

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“…Composite liners comprised of a geomembrane over a geosynthetic clay liner (GCL) are extensively used in landfills and increasingly in mining applications (Shackelford et al 2000;Bouazza 2002;Rowe et al 2004;Rowe 2005Rowe , 2012Hornsey et al 2010;Gates and Bouazza 2010;Scalia and Benson 2011;Bouazza and Gates 2014). Installation guidelines commonly recommend a minimum of 150 mm overlap of adjacent the GCLs panels (e.g., ASTM 2015) while some manufacturers recommend a minimum overlap of 300 mm (e.g., BIG 2015).…”

Section: Introductionmentioning

confidence: 99%

Field measurements of overlap reductions for two reinforced fabric-encased geosynthetic clay liners (GCLs)

2018

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Abstract:Two GCLs reported to have experienced significant shrinkage at other locations are examined on both a 3H:1V south facing slope and a relatively flat base on a silty-sand. The GCLs were overlapped by 300 mm with 400 g/m of supplemental bentonite and covered by a black 1.5 mm HDPE geomembrane to form a composite liner which was left exposed in a full-scale field test embankment for a period of almost five years. It is shown that despite the relatively uniform exposure conditions, shrinkage is highly variable with a maximum shrinkage of GCL A being 165 mm on the slope and 415 mm on the base while GCL B shrunk by up to 75 mm on the side slope and only up to 25 mm on the base. The dominant role played by variable overlap stick and heterogeneity to the locations where the overlaps are re-wetted are discussed. Based on this study of shrinkage and a related study of down-slope erosion at the same site, it is concluded that neither GCLs A and B should not be left in exposed composite liners when they can be subjected to thermal cycles that can lead to hydration and dehydration of the GCL.

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“…They are widely used in final cover systems of modern landfills to minimise migration of gases and infiltration of meteoric water. In this respect, there is a wide body of work available on their hydraulic performance in the context of landfill covers (Benson and Meer, 2009;Benson et al, 2007;Bouazza, 2002;Buckley et al, 2012;Rowe, 2013, 2014;LaGatta et al, 1997;Lin and Benson, 2000;Meer and Benson, 2007;Rowe, 2014;Rowe and Hosney, 2013;Scalia and Benson, 2011). However, experimental measurements of their permeability to gases are less widely available, and only recently has information on their advective gas flow performance became available in the context of landfill capping (Abuel-Naga and Bouazza, 2009;Bouazza and Vangpaisal, 2003Bouazza et al, 2008;Didier et al, 2000;Mendes et al, 2010;Pitanga et al, 2011;Vangpaisal and Bouazza, 2004).…”

Section: Introductionmentioning

confidence: 99%

Gas permeability of partially hydrated geosynthetic clay liner under two stress conditions

Rouf

Singh

Bouazza

et al. 2016

Environmental Geotechnics

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The results of a series of gas permeability tests, with monitoring of gravimetric/volumetric moisture content and total suction, on a commercially available needle-punched geosynthetic clay liner (GCL) are presented. GCL specimens were partially hydrated with deionised water under 2 and 20 kPa confinement prior to testing. The tests were conducted at differential pressures ranging from 1 to 10 kPa. Gas permeability was found to decrease with an increase in gravimetric/volumetric moisture content and a decrease of suction. The effect of the preconditioning stress was found to be more pronounced at gravimetric moisture contents greater than 40% (25% apparent degree of saturation, 0·30 m3/m3 volumetric moisture content), and suctions less than 1·6 MPa

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Geosynthetic clay liners

Cited by 270 publications

References 29 publications

Diffusion of Calcium Chloride in a Modified Bentonite: Impact on Osmotic Efficiency and Hydraulic Conductivity

Diffusion of Calcium Chloride in a Modified Bentonite: Impact on Osmotic Efficiency and Hydraulic Conductivity

Field measurements of overlap reductions for two reinforced fabric-encased geosynthetic clay liners (GCLs)

Gas permeability of partially hydrated geosynthetic clay liner under two stress conditions

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