Hydraulic conductivity of a dense prehydrated GCL permeated with aggressive inorganic solutions

Kolstad, Dale C.; Benson, Craig H.; Edil, Tuncer B.; Jo, Ho Young

doi:10.1680/gein.11.3.209.44488

Cited by 28 publications

(11 citation statements)

References 6 publications

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“…Bentonites amended with polymers and other organic molecules have been introduced in recent years to improve the chemical compatibility and hydraulic conductivity of GCLs permeated with aggressive leachates (e.g., Trauger and Darlington 2000;Ashmawy et al 2002;Kolstad et al 2004b;Katsumi et al 2008;Shackelford et al 2010;Scalia et al 2014;Bohnhoff and Shackelford 2014;Fehervari et al 2016;Gates et al 2016;Shaheen et al 2016;Tian et al 2016;Chen et al 2019). Bentonite-polymer composites (BPCs) composed of polymer intercalated in the montmorillonite interlayer or dry blended with bentonite have maintained low hydraulic conductivity (<10 −10 m=s) in solutions having high ionic strength, a preponderance of polyvalent cations, and extreme pH (Onikata et al 1996(Onikata et al , 1999Kolstad et al 2004b;Katsumi et al 2008;Scalia et al 2014;Tian and Benson 2014;Tian et al 2016). Mechanisms controlling the hydraulic conductivity of BPCs have been hypothesized, including increased swelling capacity (Onikata et al 1996(Onikata et al , 1999Katsumi et al 2008), prevention of cation exchange (Trauger and Darlington 2000;Ashmawy et al 2002;Deng et al 2006), and pore clogging (Scalia et al 2014;Tian et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Polymer Elution and Hydraulic Conductivity of Bentonite–Polymer Composite Geosynthetic Clay Liners

Tian

Likos

Benson

2019

J. Geotech. Geoenviron. Eng.

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Hydraulic conductivity tests were conducted on two commercially available bentonite-polymer composite (BPC) geosynthetic clay liners (GCLs) containing the same dry blend of sodium bentonite (NaB) and polymer sandwiched between two nonwoven geotextiles (GTs) bound by needlepunching: a bentonite-polymer GCL (BP GCL) and bentonite-polymer GCL with silt film (BPS GCL). The GCLs were essentially identical except that the BPS GCL contained a woven slit-film GT to constrain polymer elution. The slit-film GT was located inside the GCL adjacent to the downstream nonwoven GT. The test liquids were deionized (DI) water and 20-500 mM CaCl 2 representing dilute to high-concentration permeant solutions. Effluent from the hydraulic conductivity tests was analyzed for total organic carbon (TOC) to quantify polymer elution. Scanning electron microscopy (SEM) was used to capture how the solution chemistry affected the fabric of the BPC and how hydraulic conductivity was related to pore-scale features in the fabric. Both BPC GCLs were approximately one to four orders of magnitude less permeable than a conventional NaB GCL permeated with the same solutions. Polymer elution data and SEM images of polymer structure suggest that polymer retention in the pore space and pore clogging by polymer hydrogel are responsible for the lower hydraulic conductivity of BPC GCLs. The BPS GCL had less polymer elution and hydraulic conductivity three orders of magnitude lower than the BP GCLs when permeated with 50 and 100 mM CaCl 2 solutions because the slit-film GT reduced polymer elution from the bentonite. A conceptual framework is proposed relating solution chemistry, pore-scale fabric, and hydraulic conductivity of dry-blended BPC GCLs.

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Section: Introductionmentioning

confidence: 99%

Polymer Elution and Hydraulic Conductivity of Bentonite–Polymer Composite Geosynthetic Clay Liners

Tian

Likos

Benson

2019

J. Geotech. Geoenviron. Eng.

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“…A great number of experimental studies dealing with the effects of chemicals on hydraulic conductivity of GCLs and clays are available in the literature. Some of these studies focused on inorganic liquids , Shackelford et al 2000, Jo et al 2001, Kolstad et al 2004a, Mishra et al 2005. The other studies focused on organic liquids (Anderson et al 1985, Foreman & Daniel 1986, Bowders & Daniel 1987, Fernandez & Quigley 1989, Kaya & Fang 2000, Anandarajah 2003, Park et al 2006, and leachate components (Ruhl & Daniel 1997, Kayabalı & Mollamahmutoglu 2000, Shan & Lai 2002, Kolstad et al 2004b.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic conductivity of compacted clay liners permeated with inorganic salt solutions

2008

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Due to their low permeability, geosynthetic clay liners (GCLs) and compacted clay liners (CCLs) are the main materials used in waste disposal landfills. The hydraulic conductivity of GCLs and CCLs is closely related to the chemistry of the permeant fluid. In this study, the effect on the hydraulic conductivity of clays of five different inorganic salt solutions as permeant fluid was experimentally investigated. For this purpose, NaCl, NH(4)Cl, KCl, CaCl(2), and FeCl( 3) inorganic salt solutions were used at concentrations of 0.01, 0.10, 0.25, 0.50, 0.75 and 1 M. Laboratory hydraulic conductivity tests were conducted on low plasticity (CL) and high plasticity (CH) compacted raw clays. The change in electrical conductivity and pH values of the clay samples with inorganic salt solutions were also determined. The experimental test results indicated that the effect of inorganic salt solutions on CL clay was different from that on CH clay. The hydraulic conductivity was found to increase for CH clay when the salt concentrations increased whereas when the salt concentrations were increased, the hydraulic conductivity decreased for the CL clay.

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“…Previous studies have reported that DPH-GCLs contain the polymer sodium carboxymethyl cellulose (Na-CMC) and methanol (Kolstad et al 2004b;Katsumi et al 2008). These substances have fungicidal and preserving action; moreover, they make the bentonite flexible such that the thin hydrated bentonite sheets can be bent to form rolls ( Figure 1) without fissuring (Schroeder et al 2001).…”

Section: Dense Prehydrated Gclsmentioning

confidence: 99%

“…They also reported that the permeability of overlap specimens (with and without bentonite paste) was practically the same as that of singlelayers specimens. Kolstad et al (2004b) reported the k of a DPH-GCL permeated with deionised water (DI), and with aqueous solutions containing 1 mol/l NaCl, 1 mol/l CaCl 2 , HCl (pH ¼ 1.2) and NaOH (pH ¼ 13). The tests were conducted in flexible-wall permeameters at an average isotropic effective stress, ó9 i ¼ 20 kPa.…”

Section: Dense Prehydrated Gclsmentioning

confidence: 99%

Hydraulic conductivity of a dense prehydrated geosynthetic clay liner

Mazzieri

Emidio

2015

Geosynthetics International

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Dense prehydrated geosynthetic clay liners (DPH-GCLs) are a particular type of GCL which, unlike conventional GCLs manufactured with dry bentonite, contain bentonite prehydrated during manufacturing. DPH-GCLs are produced by a patented process that includes bentonite prehydration with a polymer solution and vacuum extrusion. This paper describes the results of permeability tests that were carried out using flexible-wall permeameters to investigate the hydraulic conductivity of a DPH GCL to water, natural seawater and a 12.5 mmol/l CaCl 2 solution. Moreover, the efficiency of the 0.1 m overlap seams between DPH-GCL panels has been investigated by means of a medium-scale permeameter able to accommodate specimens 0.305 m in diameter. Test results showed that the DPH GCL has very low hydraulic conductivity to water (10 À12 -10 À11 m/s) and preserve low permeability, of the order of 10 À11 m/s, in the presence of relatively high calcium concentration in the permeating liquid. However, the efficiency of overlap seams can be affected by the permeant type. In the presence of permeant liquids that inhibit swelling (e.g. seawater), the hydraulic efficiency of the seams needs to be improved by adding bentonite paste at the overlap interface. The hydraulic performance of the DPH-GCL is attributed to the combination of prehydration, densification and chemical amendment.

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Hydraulic conductivity of a dense prehydrated GCL permeated with aggressive inorganic solutions

Cited by 28 publications

References 6 publications

Polymer Elution and Hydraulic Conductivity of Bentonite–Polymer Composite Geosynthetic Clay Liners

Polymer Elution and Hydraulic Conductivity of Bentonite–Polymer Composite Geosynthetic Clay Liners

Hydraulic conductivity of compacted clay liners permeated with inorganic salt solutions

Hydraulic conductivity of a dense prehydrated geosynthetic clay liner

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