Hydration and Cation Exchange during Subgrade Hydration and Effect on Hydraulic Conductivity of Geosynthetic Clay Liners

Bradshaw, Sabrina L.; Benson, Craig H.; Scalia, Joseph

doi:10.1061/(asce)gt.1943-5606.0000793

Cited by 74 publications

(21 citation statements)

References 23 publications

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“…It had been reported that for montmorillonites in the presence of Na + and Ca 2+ ions in the exchangeable sites, a maximum viscosity is obtained when Ca 2+ ions occupy about 40% of these sites (Bleifuss, 1973). This balance of cations in montmorillonite can be affected by the presence of extra cations in the surroundings as it was studied by Bradshaw et al (2013). They explained that Na + ions were exchanged by divalent cations present in the environment and that one of the sources was the dissolution of calcite.…”

Section: Discussionmentioning

confidence: 97%

Interactions of clay minerals in copper–gold flotation: Part 2 — Influence of some calcium bearing gangue minerals on the rheological behaviour

Cruz

Peng

2015

International Journal of Mineral Processing

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Section: Discussionmentioning

confidence: 97%

Interactions of clay minerals in copper–gold flotation: Part 2 — Influence of some calcium bearing gangue minerals on the rheological behaviour

Cruz

Peng

2015

International Journal of Mineral Processing

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“…These allow the collection of the evaporated moisture from the underlying clay barriers, causing them to later condense and fall by gravity away from the original source due to diurnal temperature changes. In addition to above, particular attention must also be given to cracking that occur due to the cation exchange within bentonite which normally occurs over a period of approximately 1-3 years (Bradshaw et al, 2013;Benson and Meer, 2009;Wijeyesekera, 2003;Egglofstein, 1997). The bentonite in the linear system generally is found either as air dried granulated/powdered or as prehydrated and extruded form.…”

Section: Case 2: Cracking Effect Of the Bentonite-based Barriersmentioning

confidence: 99%

Hydraulic Flow through Engineering Bentonite-Based Containment Barriers

Loh¹,

Wijeyesekera²

2015

American Journal of Applied Sciences

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This paper presents the use of software modelling as a tool to study the impact of hydraulic "resistivity" on the contaminant transport through bentonite-based containment barriers. A sensitivity analysis on the predicted data was carried out by varying the boundary conditions as well as the hydraulic resistance to flow through varying contaminant transport parameters. Accordingly, both advective and diffusive flow processes are considered as that which resists the flow. In particular, the effect on the contaminant migration due to desiccation cracking is explored. Laboratory evidence is provided and discussed to show how the initial microstructure of the clay influences the development of subsequent macro structural features such as shrinkage crack patterns. The effect of these cracks and the intensity of cracking on the contaminant migration are modelled and pragmatically discussed. Additionally, the effect on the hydraulic conductivity of bentonite-based barriers, when permeated with non-standard liquids is discussed and a typical analytical output is presented.

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“…Numerous laboratory investigations have examined the effect of several factors on the hydraulic performance of GCLs such as cation exchange, interaction with different permeants, wet-dry cycles, and freeze-thaw cycles (e.g., Shan and Daniel 1991;Boardman and Daniel 1996;Petrov and Rowe 1997;Lin and Benson 2000;Shackelford et al 2000Shackelford et al , 2010Jo et al 2005;Lee et al 2005;Rowe et al 2006;Bouazza et al 2007;Brown and Shackelford 2007;Benson and Meer 2009;Lange et al 2010;Rosin-Paumier et al 2011;Rosin-Paumier and Touze-Foltz 2012;Rowe and Abdelatty 2012;Bradshaw et al 2013Bradshaw et al , 2016Mazzieri et al 2013;Rowe and Hosney 2013;Sari and Chai 2013). There have been far fewer studies examining the hydraulic performance of GCLs after a period of field exposure in applications such as covers or caps under low applied stress and these studies have given rise to some apparently inconsistent findings as discussed below (James et al 1997;Benson et al 2007Benson et al , 2010Meer and Benson 2007;Benson 2010a, 2011;Buckley et al 2012;Hosney and Rowe 2013).…”

Section: Introductionmentioning

confidence: 99%

Insight into hydraulic conductivity testing of geosynthetic clay liners (GCLs) exhumed after 5 and 7 years in a cover

et al. 2017

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Four geosynthetic clay liners (GCLs) serving as single liners were exhumed from below 0.7 m of silty sand on a 3:1 (horizontal:vertical) north-facing slope at the QUELTS site in Godfrey, Ontario, after 5 and 7 years. The 300 mm GCL overlaps with 0.4 kg/m supplemental bentonite were all physically intact. The exchangeable bound sodium was completely replaced with divalent cations. The GCL with the smallest needle-punched bundle size (average of 0.7 mm) and percentage area covered by bundles (4%) maintained low hydraulic conductivity (k) when tested under 0.07-1.2 m head with 10 mmol/L CaCl 2 solution as the permeant. For GCLs with larger bundles (1.1-1.6 mm) and higher percentage area covered by bundles (9%-14%), k was low when the head was low (0.07 m). Once the applied head increased, k increased by 1-4 orders of magnitude depending on the (i) hydraulic gradient, (ii) size and number of the needle-punched bundles, and (iii) structure and mass of the bentonite per unit area. The results suggest that the GCLs can perform effectively as a single hydraulic barrier in covers providing that the head above the GCL is kept low (e.g., by a suitable drainage layer above the GCL).Key words: geosynthetic clay liner, cover, overlaps, cation exchange, hydraulic conductivity, field study. Résumé :Quatre couches d'argile géosynthétiques (CAG) agissant comme des parois uniques ont été exhumés d'une profondeur en dessous de 0,7 m sur un sable limoneux de 3 : 1 (horizontale : verticale) au versant nord au site QUELTS dans Godfrey, en Ontario, après 5 et 7 ans. Les 300 mm de CAG se superposent au 0,4 kg/m de bentonite supplémentaire qui est physiquement intact. Le sodium lié échangeable a été complètement remplacé par des cations divalents. Le CAG avec la plus petite taille de paquet aiguilleté (moyenne de 0,7 mm) et le pourcentage de la superficie couverte par des faisceaux (4 %) a maintenu une faible conductivité hydraulique (k) lors de l'essai sous une tête de 0,07 à 1,2 m avec une solution 10 mM de CaCl 2 comme perméant. Pour les CAG avec de plus grands faisceaux (1,1 à 1,6 mm) et un pourcentage plus élevé de la zone couverte par des faisceaux (9-14 %), k est faible quand la tête était faible (0,07 m). Une fois que la tête appliquée a augmenté, k a augmenté de 1 à 4 ordres de grandeur en fonction (i) du gradient hydraulique, (ii) du nombre et de la taille des faisceaux aiguilletés et (iii) de la structure et la masse de la bentonite par unité de surface. Les résultats suggèrent que le CAG peut fonctionner efficacement comme une seule barrière hydraulique dans des couvercles à condition que la tête au-dessus du CAG soit maintenue à un niveau bas (p. ex., par une couche de drainage approprié au-dessus du GCL). [Traduit par la Rédaction] Mots-clés : couche d'argile géosynthétique, couvercle, chevauchements, échange de cations, conductivité hydraulique, étude sur le terrain.

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Hydration and Cation Exchange during Subgrade Hydration and Effect on Hydraulic Conductivity of Geosynthetic Clay Liners

Cited by 74 publications

References 23 publications

Interactions of clay minerals in copper–gold flotation: Part 2 — Influence of some calcium bearing gangue minerals on the rheological behaviour

Interactions of clay minerals in copper–gold flotation: Part 2 — Influence of some calcium bearing gangue minerals on the rheological behaviour

Hydraulic Flow through Engineering Bentonite-Based Containment Barriers

Insight into hydraulic conductivity testing of geosynthetic clay liners (GCLs) exhumed after 5 and 7 years in a cover

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