Laboratory investigation of GCL hydration from clayey sand subsoil

Anderson, Richard W.; Rayhani, Mohammad T.; Rowe, R. Kerry

doi:10.1016/j.geotexmem.2011.10.005

Cited by 73 publications

(32 citation statements)

References 16 publications

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“…Koerner and Koerner 2005;Thiel and Richardson 2005;Bostwick et al 2010;Rowe et al 2011a;, and suppressed hydration of GCLs compared to hydration under isothermal conditions (e.g. Rayhani et al 2011;Rowe et al 2011b;Anderson et al 2012;Chevrier et al 2012;Siemens et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Observations of bentonite erosion from solar-driven moisture migration in GCLs covered only by a black geomembrane

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Brachman

Rowe

2015

Geosynthetics International

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Manufacturers of geosynthetic liner materials recommend that composite geomembrane/geosynthetic clay liners (GCLs) be covered in a timely fashion to avoid potential issues that may arise under the action of long-term solar exposure. In this paper, field evidence of a new, never before reported solar-exposure driven damage mechanism for GCLs covered only by a black geomembrane and left exposed for more than 3 years is presented. Solar exposure can give rise to a large daily variation in geomembrane temperature, which causes a moisture cycle within the interface between the geomembrane and GCL resulting in the formation and flow of condensed moisture beneath the geomembrane. All four of the GCL products investigated at the Queen's University Environmental Liner Test Site were shown to have experienced significant bentonite erosion after 4.7 years of exposure. Erosion was identified in the field through a tactile survey of GCL panels in which the stiffness response of the GCL to touch was used to identify eroded zones. A change in the colour of the GCL, although useful to identify possibly eroded zones in some GCL products, proved ineffective in others. Erosion features were observed with widths up to and exceeding 200 mm across, making them unlikely to undergo self-healing upon hydration and application of normal stress. As a result, the observed erosion features would have severe adverse consequences for leakage rates through the GCL component of a composite liner barrier system. These observations provide yet another strong motivation for timely covering of composite landfill liner systems.

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Section: Introductionmentioning

confidence: 99%

Observations of bentonite erosion from solar-driven moisture migration in GCLs covered only by a black geomembrane

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Brachman

Rowe

2015

Geosynthetics International

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“…It is known that the uptake of moisture by a GCL is dependent on the initial water content of the subgrade (Rayhani et al 2011;Benson 2013;Siemens et al 2013), the subgrade particle size distribution and mineralogy which both affect the subgrade water retention characteristics (Anderson et al 2012;Sarabian and Rayhani 2013;Bouazza et al 2016), the hydraulic conductivity of the subgrade (Chevrier et al 2012), the water retention characteristics of the GCL (Beddoe et al 2011), and the nature of thermal cycles (Rowe et al 2011b). At this site the soil had a relatively uniform mineralogy, particle size, and initial water content although there was some variability from location to location (with the western half of the site being a little siltier with higher initial water contents than the eastern half of the site which was generally sandier with lower initial water contents; ) however since GCL B was placed at both the eastern and western ends of the site and GCL A was located toward the centre of the site, this variability does not appear to offer an explanation for the observed behaviour.…”

Section: R a F Tmentioning

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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“…Thus, GCL shear tests should generally be conducted in the fully hydrated condition to be conservative Stark 1997;Daniel 2013). Recent studies have also shown that the final degree of hydration is affected by many factors, including initial moisture content of the subsoil, temperature, heat cycles, confining pressure, and method of GCL manufacture (Rayhani et al 2011;Anderson et al 2012;Chevrier et al 2012;Siemens et al 2012). Such factors may need to be taken into account for special cases.…”

Section: Need For Conditioningmentioning

confidence: 99%

“…until volume change ceases) under the normal stress expected in the field at the time of hydration. Experimental work conducted by Daniel et al (1993), Gilbert et al (1996a), , Anderson et al (2012) and others indicate that, depending on conditions, full hydration of non-encapsulated GCLs can require a hydration time (t h ) as long as several weeks, and possibly several months. For example, delayed failure of three of the Cincinnati test plots (Section 6.4) occurred about two months after installation and was attributed to gradual bentonite hydration Daniel 2013).…”

Section: Need For Conditioningmentioning

confidence: 99%

State-of-the-art report: GCL shear strength and its measurement – ten-year update

Fox

Stark

2015

Geosynthetics International

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This paper presents an invited update to our 2004 state-of-the-art report and provides a comprehensive source of information on the shear strength and shear strength testing of geosynthetic clay liners (GCLs). Essential concepts of shear stress-displacement behavior and shear strength are presented, followed by detailed discussions on the laboratory measurement of the shear strength of GCLs and GCL interfaces. The paper also provides recommendations for the selection of design strength envelopes for stability analyses and checklists to assist users in the specification of GCL shear testing programs. North American practice is emphasized and discussions are focused primarily within the context of landfill bottom liner and cover systems. Conclusions and recommendations are provided with regard to GCL shear strength behavior and current GCL strength testing practice, improvements for GCL strength testing are suggested, and future research needs are identified.

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Laboratory investigation of GCL hydration from clayey sand subsoil

Cited by 73 publications

References 16 publications

Observations of bentonite erosion from solar-driven moisture migration in GCLs covered only by a black geomembrane

Observations of bentonite erosion from solar-driven moisture migration in GCLs covered only by a black geomembrane

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

State-of-the-art report: GCL shear strength and its measurement – ten-year update

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