A Comparison of Sample Preparation Methodology in the Evaluation of Geosynthetic Clay Liner (GCL) Hydraulic Conductivity PDF Download
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Author: S. Lucas
Publisher:
ISBN:
Category : Flexible Wall Permeameter
Languages : en
Pages : 8
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Book Description
The method of preparing a single needle-punched GCL product for evaluation of hydraulic conductivity in a flexible wall permeameter was examined. The test protocol utilized for this evaluation was GRI Test Method GCL-2 Permeability of GCLs. The GCL product consisted of bentonite clay material supported by a woven and a non-woven geotextile on either side. The method preparation focused on the procedure for separating the test specimen from the larger sample and whether these methods produced difficulty in generating reliable test data. The methods examined included cutting with a razor knife, scissors, and a circular die with the perimeter of the test area under wet and dry conditions. In order to generate as much data as possible, tests were kept brief. Flow was monitored only long enough to determine whether or not preferential flow paths appeared to be present. The results appear to indicate that any of the methods involved will work. Difficulties arose not from the development of preferential flow paths around the edges of the specimens, but from the loss of bentonite from the edges during handling.
Author: S. Lucas
Publisher:
ISBN:
Category : Flexible Wall Permeameter
Languages : en
Pages : 8
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Book Description
The method of preparing a single needle-punched GCL product for evaluation of hydraulic conductivity in a flexible wall permeameter was examined. The test protocol utilized for this evaluation was GRI Test Method GCL-2 Permeability of GCLs. The GCL product consisted of bentonite clay material supported by a woven and a non-woven geotextile on either side. The method preparation focused on the procedure for separating the test specimen from the larger sample and whether these methods produced difficulty in generating reliable test data. The methods examined included cutting with a razor knife, scissors, and a circular die with the perimeter of the test area under wet and dry conditions. In order to generate as much data as possible, tests were kept brief. Flow was monitored only long enough to determine whether or not preferential flow paths appeared to be present. The results appear to indicate that any of the methods involved will work. Difficulties arose not from the development of preferential flow paths around the edges of the specimens, but from the loss of bentonite from the edges during handling.
Author: Larry W. Well
Publisher: ASTM International
ISBN: 0803124716
Category : Geosynthetics
Languages : en
Pages : 270
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Book Description
An engineering perspective on the liners, which are used as barriers for containing liquid and in conjunction with geomembranes in landfills and capping systems. Explore aspects of testing for shear strength and long-term creep, issues and methods of testing for hydraulic conductivity, and specifica
Author: RJ. Petrov
Publisher:
ISBN:
Category : Bentonite
Languages : en
Pages : 14
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Book Description
Specimen preparation, installation, and testing procedures are presented for testing a needle-punched geosynthetic clay liner (GCL) in a consolidation-type, fixed-ring constant-flow-rate hydraulic conductivity apparatus. The proposed approach is illustrated by reporting the results obtained for a GCL statically confined to effective stresses of ~3 and ~35 kPa, hydrated and permeated with distilled water and concentrated aqueous salt solutions (0.6 and 2.0 N NaCl), and sequentially permeated with concentrated aqueous salt solutions (0.6 and 2.0 N NaCl) after initial permeation with distilled water. The issue of potential preferential sidewall flow in the fixed-ring permeameter tests was then addressed by comparing results with those conducted under otherwise similar testing conditions in a double-ring and flexible-wall permeameter. Reasonable reproducibility of the test results was obtained between the different types of permeameters, suggesting that, if present, preferential sidewall flow was negligibly small and was not significant on the calculated hydraulic conductivity values. This conclusion was found to be valid for the range of permeant types (distilled water and 0.6 and 2.0 N NaCl), static-confining stresses, and hydrating mediums considered. Premature arrival of the salt solution front in the effluent (i.e., solute breakthrough) during fixed-ring hydraulic conductivity testing was explained as a probable diffusion-dominated transport mechanism through the relatively thin GCL specimens.
Author: Robert E. Mackey
Publisher: ASTM International
ISBN: 0803134843
Category : Clay
Languages : en
Pages : 161
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Book Description
Soon after the inception of ASTM D35.04 Subcommittee on Geosynthetic Clay Liners, the first symposium on Testing and Acceptance Criteria for Geosynthetic Clay Liners (GCLs), STP 1308, was held on 29 January 1996, in Atlanta, Georgia. The intention of the symposium was to bring together the current knowledge and understanding regarding this relatively new product used in containment systems. Since that symposium, numerous GCL standards have been developed along with a greater appreciation of the product's capabilities and limitations. ASTM D35 determined it was time to assess the current state of GCL technology to better address possible revisions of the present ASTM GCL standards and determine what new standards will be required in the future.
Author: DE. Daniel
Publisher:
ISBN:
Category : Bentonite
Languages : en
Pages : 12
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Book Description
An important property of geosynthetic clay liners (GCLs) is hydraulic conductivity. The authors describe and evaluate a new device, a GCL flowbox, that offers several advantages over large tanks or flexible-wall permeameters. The GCL flowbox can be used to test large-scale intact specimens, overlapped specimens with a full-width seam, and specimens subjected to environmental stresses such as freeze-thaw. A transparent, acrylic GCL flowbox was developed for testing at low normal stresses, and a metal version was developed for applying higher normal stresses. Results from the GCL flowbox compared favorably to results obtained with tanks and flexible-wall permeameters. It is concluded that the GCL flowbox provides a convenient and reliable testing methodology for verifying the hydraulic conductivity of both intact specimens and overlapped GCL panels.
Author: XD. Wang
Publisher:
ISBN:
Category : Clay minerals
Languages : en
Pages : 7
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Book Description
Hydraulic conductivity tests were conducted using open and constant-volume permeation systems on specimens from a geosynthetic clay liner (GCL). Two constant volume (CV) systems were employed: the falling-head constant-volume (FHCV) system and the constant-head constant-volume (CHCV) system. A conventional burette system using pressurized air was employed for the open system (OS) tests. The test results show that hydraulic conductivity tests can be conducted 30 or more times faster with the FHCV and CHCV systems than with an open system. Typically the permeation portion of the FHCV and CHCV tests can be conducted in one-half day. Slightly lower hydraulic conductivities are measured with the CV systems due to the slightly higher effective stress applied during testing with these systems. The CHCV system has several advantages over the FHCV system, including minimizing initial transient behavior, constant applied effective stress during testing, and simpler calculations.
Author: Joseph Scalia
Publisher:
ISBN:
Category :
Languages : en
Pages : 310
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Book Description
Author: Nimisha H. Patel
Publisher:
ISBN:
Category : Clay
Languages : en
Pages : 170
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Book Description
Author: Scott M. Vasko
Publisher:
ISBN:
Category :
Languages : en
Pages : 404
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Book Description
Author: G. Didier
Publisher:
ISBN:
Category : Borehole
Languages : en
Pages : 22
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Book Description
For waste facilities, field assessment of the hydraulic conductivity of fine- grained soils has been a real challenge for the past decades that has led to several types of test methods. Although standards (ASTM, NF, etc.) have been adopted in many countries, any test method needs careful application for constructing quality-control programs. The type of apparatus, its geometry, and even specimen preparation may be major sources of discrepancy. We compared hydraulic-conductivity values obtained from various field-testing methods (open, sealed, single and double infiltrometers, and borehole methods), and laboratory-testing methods such as oedometer cells or rigid and flexible-wall permeameters. Three materials were tested in this study: a compacted sandbentonite mixture, compacted clayey silt, and natural sandy clay. The field tests were run on soil-test pads whose characteristics were defined beforehand in the laboratory and the field. Comparison of the results shows a large range of hydraulic-conductivity values for a single soil sample. Such variability can commonly be explained by a scale effect, as demonstrated by the use of various types of diameter or geometry for the field or laboratory tests. Soil behavior (swelling or shrinkage) and test-analysis methods (saturated or unsaturated-flow analysis) are other important parameters. In conclusion, we identified the main problems affecting tests with infiltrometers and permeameters, and how they can be reduced or avoided by the improvement of current techniques.
