Designation: D6392 − 12

Standard Test Method for

Determining the Integrity of Nonreinforced Geomembrane
Seams Produced Using Thermo-Fusion Methods1
This standard is issued under the fixed designation D6392; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

1. Scope industry accepted trade descriptions and are not technical material
classifications based upon material density.
1.1 This test method describes destructive quality control
1.4 This standard does not purport to address all of the
and quality assurance tests used to determine the integrity of
safety concerns, if any, associated with its use. It is the
geomembrane seams produced by thermo-fusion methods.
responsibility of the user of this standard to establish appro-
This test method presents the procedures used for determining
priate safety and health practices and determine the applica-
the quality of nonbituminous bonded seams subjected to both
bility of regulatory limitations prior to use.
peel and shear tests. These test procedures are intended for
nonreinforced geomembranes only. 2. Referenced Documents
1.2 The types of thermal field seaming techniques used to 2.1 ASTM Standards:2
construct geomembrane seams include the following. D638 Test Method for Tensile Properties of Plastics
1.2.1 Hot Air—This technique introduces high-temperature D4439 Terminology for Geosynthetics
air or gas between two geomembrane surfaces to facilitate D5199 Test Method for Measuring the Nominal Thickness
melting. Pressure is applied to the top or bottom geomembrane, of Geosynthetics
forcing together the two surfaces to form a continuous bond. D5994 Test Method for Measuring Core Thickness of Tex-
1.2.2 Hot Wedge (or Knife)—This technique melts the two tured Geomembranes
geomembrane surfaces to be seamed by running a hot metal 2.2 EPA Standards:
wedge between them. Pressure is applied to the top or bottom EPA/600/2-88/052 Lining of Waste Containment and Other
geomembrane, or both, to form a continuous bond. Some Containment Facilities; Appendix N, Locus of break codes
seams of this kind are made with dual bond tracks separated by for various types of FML seams3
a nonbonded gap. These seams are sometimes referred to as
dual hot wedge seams or double-track seams. 3. Terminology
1.2.3 Extrusion—This technique encompasses extruding 3.1 Definitions of Terms Specific to This Standard:
molten resin between two geomembranes or at the edge of two 3.1.1 geomembrane, n—essentially impermeable geosyn-
overlapped geomembranes to effect a continuous bond. thetic composed of one or more synthetic sheets.
1.3 The types of materials covered by this test method 3.1.2 quality assurance, n—all planned and systematic ac-
include the following. tions necessary to provide adequate confidence that an item or
1.3.1 Very Low Density Polyethylene (VLDPE). a facility will perform satisfactorily in service.
1.3.2 Linear Low Density Polyethylene (LLDPE).
3.1.3 quality control, n—the operational techniques and the
1.3.3 Very Flexible Polyethylene (VFPE).
activities, which sustain a quality of material, product, system,
1.3.4 Linear Medium Density Polyethylene (LMDPE).
or service that will satisfy given needs; also the use of such
1.3.5 High Density Polyethylene (HDPE).
techniques and activities.
1.3.6 Polyvinyl Chloride (PVC).
1.3.7 Flexible Polypropylene (fPP). 4. Significance and Use
NOTE 1—The polyethylene identifiers presented in 1.3.1-1.3.5 describe 4.1 The use of geomembranes as barrier materials to restrict
the types of materials typically tested using this test method. These are liquid migration from one location to another in soil and rock

1 2
This test method is under the jurisdiction of ASTM Committee D35 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomem- contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
branes. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved July 1, 2012. Published September 2012. Originally the ASTM website.
3
approved in 1999. Last previous edition approved in 2008 as D6392–08. DOI: Available from the Superintendent of Documents, US Government Printing
10.1520/D6392-12. Office, Washington, DC 20402.

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 D6392 − 12
has created a need for a standard test method to evaluate the such that the seam is perpendicular to the longer dimension of
quality of geomembrane seams produced by thermo-fusion the strip specimen.
methods. In the case of geomembranes, it has become evident
6.3 Conditioning—Samples should be conditioned for 40 h
that geomembrane seams can exhibit separation in the field
in a standard laboratory environment that conforms to the
under certain conditions. Although this is an index type test
requirements for testing geosynthetics as stated in Terminology
method used for quality assurance and quality control
D4439. Long sample conditioning times typically are not
purposes, it is also intended to provide the quality assurance
engineer with sufficient seam peel and shear data to evaluate possible for most applications that require seam testing. Prior
seam quality. Recording and reporting data, such as separation to testing, samples should be conditioned for a minimum of 1
that occurs during the peel test and elongation during the shear h at 23 6 2°C and a relative humidity between 50 and 70 %.
test, will allow the quality assurance engineer to take measures
necessary to ensure the repair of inferior seams during facility 7. Destructive Test Methods
construction, and therefore, minimize the potential for seam 7.1 Peel Testing—Subject five specimens to the 90° “T-
separation in service. Peel” test (see Fig. 2). If the tested sample is a dual hot wedge
seam, five specimens must be examined for each external track
5. Apparatus of the seam. Maintaining the specimen in a horizontal position
5.1 Tensile instrumentation shall meet the requirements throughout the test is not required. Fully grip the test specimen
outlined in Test Method D638. across the width of the specimen. Grip the peel specimen by
5.2 Grip Faces—Grip faces shall be 25 mm (1 in.) wide and securing grips 25 mm (1 in.) on each side of the start of the
a minimum of 25 mm (1 in.) in length. Smooth rubber, fine seam bond, a constant machine cross head speed of 50 mm (2
serrated or coarse serrated grip faces have all been found to be in.)/min for HDPE, LMDPE, and PVC, 500 mm (20 in.)/min
suitable for testing geomembrane seams. for LLDPE, VLDPE, VFPE, and fPP. The test is complete
when the specimen ruptures.
6. Sample and Specimen Preparation
7.2 Shear Testing—Subject five specimens to the shear test
6.1 Seam Samples—Cut a portion of the fabricated seam (see Fig. 2). Fully support the test specimen within the grips
sample from the installed liner in accordance with the project across the width of the specimen. Secure the grips 25 mm (1
specifications. It is recommended that the cutout sample be 0.3 in.) on each side of the start of the seam bond, a constant
m (1 ft) wide and 0.45 m (1.5 ft) in length with the seam machine cross head speed of 50 mm (2 in.)/min for LMDPE
centered in the middle. and HDPE, 500 mm (20 in.)/min for fPP, LLDPE, VFPE,
6.2 Specimen Preparation—Ten specimens shall be cut VLDPE, and PVC. The test is complete for HDPE and LMDPE
from the sample submittal. The specimens shall be die cut once the specimen has elongated 50 %. PVC, fPP, LLDPE,
using a 25 mm (nominal 1 in.) wide by a minimum of 150 mm VFPE and VLDPE geomembranes should be tested to rupture.
(nominal 6 in.) long die. Specimens that will be subjected to NOTE 2—Both peel and shear tests for fPP, LLDPE, VLDPE, and PVC
peel and shear tests shall be selected alternately from the geomembranes have been tested routinely at both 2 and 20 in./min. When
sample and labeled as shown in Fig. 1. Specimens shall be cut conducting seam peel or shear testing for quality control, or quality

FIG. 1 Seam Sample

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 D6392 − 12

FIG. 2 Shear and T-Peel Specimens

assurance purposes, or both, it may be necessary to select the manufac- 8.1.6 Using the same calipers, record the dimensions of
turer’s recommended testing speed. In the absence of explicit testing each peeled area.
speed requirements, follow those recommended in 7.1 and 7.2.
8.1.7 Using the recorded dimensions, calculate percent peel
8. Calculations and Observations as follows and round to the nearest 5%.
S 5 100* A⁄A o (1)
8.1 Estimate of Seam Peel Separation—Visually estimate
the seam separation demonstrated prior to rupture for peel where:
specimens. The estimate shall be based upon the proportion of S = Percent peel separation
the area of the separated bond, to the area of original bonding A = Area of peel separation measured
to the nearest 5%. However, if at any point across the width of Ao = Area of original bonded region (not including track
the peel specimen, seam separation continues to the other side weld, tack weld, or squeeze-out, see Note 3 and Note 4)
of the bonded area, the estimate of seam peel separation shall NOTE 3—During the thermo-fusion welding process, some of the
be 100 % regardless of the proportion of the area of the melted polymer may be shifted to the outside of the weld during the
separated bond to the area of the original bonding. pressing of the geomembrane panels together. This melted polymer is
sometimes called “squeeze-out” or “bleed out” and is not considered part
8.1.1 In cases of dispute, the peel separation estimate may of the bond. Care must be exercised during estimation of the seam peel
be documented via direct measure. separation to segregate the squeeze or bleed out area from the peeled bond
8.1.2 Procedure: Determine the total area of bonded area for area. The reported peel separation shall include the peeled bond area only.
which the peel test was performed using calipers to span NOTE 4—The exact area of original bond (Ao) for use in Equation 1 for
measure the maximum length of the bond being careful not peel separation is sometimes ambiguous. For most cases, the area of peel
measured for thermo fusion extrusion seams is that area defined by the
include squeeze-out or tack welded areas. Verify the seam width of the specimen multiplied by the distance between the termination
width of one inch. of the top geomembrane and the outermost edge of the extrusion weld
8.1.3 Assign appropriate geometric shapes to approximate along the bottom geomembrane. To be counted as part of the weld, the
the area of each separated portion of the peeled zone. extruded material must be at least as thick as the nominal thickness of the
8.1.4 Place the peeled specimen flat against the surface of a geomembrane.
flat bed scanner set at 100% scale. 8.2 Rupture Mode Selection—Determine the locus of break
8.1.5 Produce a record of the peeled area for easier shape for both the peel and shear specimens as shown in Figs. 3 and
assignment and peeled area determination. Care should be 4. The locus of break for shear specimens that do not rupture
taken to assure intimate contact between the peeled specimen prior to test end (50 % elongation) shall be interpreted as
and the scanner surface so as to preserve dimensions. occurring in the membrane that exhibits yielding.

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 D6392 − 12

FIG. 3 Locus-of-Break Codes for Dual Hot Wedge Seams in Unreinforced Geomembranes Tested for Seam Strength in Shear and Peel
Modes

8.3 Shear Percent Elongation—Calculate the percent elon- 9.1.1 Report the individual peel and shear specimen maxi-
gation on shear specimens according to Eq 2. Divide the mum unit tension values in N/mm of width (lb/in.).
extension at test end by the original gage length of 25 mm and
NOTE 6—If requested, report the maximum peel or shear stress. This
multiply by 100. calculation will require an accurate measurement of thickness for each
L specimen. These measurements should be made in accordance with Test
Elongation~ E ! 5 3 100 (2) Method D5199 for smooth geomembranes and Test Method D5994 for
L0
textured geomembranes.
where: 9.1.2 Report the cross head speed used during peel and
L = extension at test end, and shear testing.
L0 = original gauge length. 9.1.3 Report the average of the individual peel and shear
NOTE 5—The intent of measuring elongation using this test method is sample values recorded.
to identify relatively large reductions in typical break elongation values of 9.1.4 If the peel or shear specimen does not rupture, report
seam samples. Length is defined as the distance from one grip to the seam
edge. Using this definition implies that all strain experienced by the the elongation at the maximum cross-head travel limitation. If
specimen during the shear test occurs on one side of the seam. Of course the gage length is reduced to less than 25 mm (1 in.), this must
this assumption is inaccurate, since some strain will occur on each side of be noted in the report.
the seam, and in the seam area itself; however, it is difficult to make an 9.1.5 Report the mode of specimen rupture for peel and
accurate measurement of the strain distribution which occurs in the shear specimens according to Fig. 3 or Fig. 4.
specimen during testing. Further, it is not critical to know the exact
location of all the strain which occurs during testing but rather to simply
identify when significant reductions in elongation (when compared with
the typical elongation of a new material) have occurred.

9. Report
9.1 The report shall include the following information.

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 D6392 − 12

FIG. 4 Locus-of-Break Codes for Fillet Extrusion Weld Seams in Unreinforced Geomembranes Tested for Seam Strength in Shear and
Peel Modes

NOTE 7—“Locus-of-Failure” (Figs. 3 and 4) include only some of the 10. Precision and Bias
typically found seam configurations found in the industry. When this test
method is applied to seams bonded in configurations other than those 10.1 No statement can be made at this time concerning
identified in Fig. 3 or Fig. 4, the users of this test method must agree on precision or bias.
applicable descriptions for modes of specimen rupture.

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 D6392 − 12
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