ASTM D7749-11
(Test Method)Standard Test Method for Determining Integrity of Seams Produced Using Thermo-Fusion Methods for Reinforced Geomembranes by the Grab Method
Standard Test Method for Determining Integrity of Seams Produced Using Thermo-Fusion Methods for Reinforced Geomembranes by the Grab Method
SIGNIFICANCE AND USE
The use of reinforced geomembranes as barrier materials has created a need for a standard test method to evaluate the quality of seams produced by thermo-fusion methods. This test method is used for quality control purposes and is intended to provide quality control and quality assurance personnel with data to evaluate seam quality.
Values obtained with this method can be correlated to . The purpose of correlating these methods was for the strength of parent material measured in to be comparable to seam strength measured by the test outlined here. The value obtained with this method cannot be compared to values for strip method for parent material or ASTM DXXXX strip method for reinforced seams.
SCOPE
1.1 This test method describes destructive quality control tests used to determine the integrity of thermo-fusion seams made with reinforced geomembranes. A test procedure is described that uses seam tests using grab specimens for seam shear strength.
1.2 The types of thermal field and factory seaming techniques used to construct geomembrane seams include the following.
1.2.1 Hot Air—This technique introduces high-temperature air between two geomembrane surfaces to facilitate melting. Pressure is applied to the top or bottom geomembrane, forcing together the two surfaces to form a continuous bond.
1.2.2 Hot Wedge—This technique melts the two geomembrane surfaces to be seamed by running a hot metal wedge between them. Pressure is applied to the top and bottom geomembrane to form a continuous bond. Some seams of this kind are made with dual tracks separated by a non-bonded gap. These seams are sometimes referred to as dual hot wedge seams or double-track seams.
1.2.3 Extrusion—This technique encompasses extruding molten resin between two geomembranes or at the edge of two overlapped geomembranes to effect a continuous bond.
1.2.4 Radio Frequency (RF) or Dielectric—High frequency dielectric equipment is used to generate heat and pressure to form an overlap seam in factory fabrication.
1.2.5 Impulse—Clamping bars heated by wires or a ribbon melts the sheets clamped between them. A cooling period while still clamped allows the polymer to solidify before being released.
1.3 The types of materials covered by this test method include, but are not limited to, reinforced geomembranes made from the following polymers.
1.3.1 Very Low Density Polyethylene (VLDPE).
1.3.2 Linear Low Density Polyethylene (LLDPE).
1.3.3 Flexible Polypropylene (fPP).
1.3.4 Polyvinyl Chloride (PVC).
1.3.5 Chlorosulfonated polyethylene (CSPE).
1.3.6 Ethylene Interpolymer Alloy (EIA).
1.4 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D7749 − 11
Standard Test Method for
Determining Integrity of Seams Produced Using Thermo-
Fusion Methods for Reinforced Geomembranes by the Grab
Method
This standard is issued under the fixed designation D7749; 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 1.3.3 Flexible Polypropylene (fPP).
1.3.4 Polyvinyl Chloride (PVC).
1.1 This test method describes destructive quality control
1.3.5 Chlorosulfonated polyethylene (CSPE).
tests used to determine the integrity of thermo-fusion seams
1.3.6 Ethylene Interpolymer Alloy(EIA).
made with reinforced geomembranes. A test procedure is
described that uses seam tests using grab specimens for seam 1.4 Units—The values stated in either SI units or inch-
shear strength. pound units are to be regarded separately as standard. The
values stated in each system may not be exact equivalents;
1.2 The types of thermal field and factory seaming tech-
therefore,eachsystemshallbeusedindependentlyoftheother.
niques used to construct geomembrane seams include the
Combining values from the two systems may result in non-
following.
conformance with the standard.
1.2.1 Hot Air—This technique introduces high-temperature
1.5 This standard does not purport to address all of the
air between two geomembrane surfaces to facilitate melting.
safety concerns, if any, associated with its use. It is the
Pressure is applied to the top or bottom geomembrane, forcing
responsibility of the user of this standard to establish appro-
together the two surfaces to form a continuous bond.
priate safety and health practices and determine the applica-
1.2.2 Hot Wedge—This technique melts the two geomem-
bility of regulatory limitations prior to use.
brane surfaces to be seamed by running a hot metal wedge
between them. Pressure is applied to the top and bottom
2. Referenced Documents
geomembrane to form a continuous bond. Some seams of this
kind are made with dual tracks separated by a non-bonded gap. 2.1 ASTM Standards:
D4439 Terminology for Geosynthetics
These seams are sometimes referred to as dual hot wedge
seams or double-track seams. D7004 Test Method for Grab Tensile Properties of Rein-
1.2.3 Extrusion—This technique encompasses extruding forced Geomembranes
molten resin between two geomembranes or at the edge of two D7003 Test Method for Strip Tensile Properties of Rein-
overlapped geomembranes to effect a continuous bond. forced Geomembranes
1.2.4 Radio Frequency (RF) or Dielectric—High frequency D76 Specification for Tensile Testing Machines for Textiles
dielectric equipment is used to generate heat and pressure to
3. Terminology
form an overlap seam in factory fabrication.
1.2.5 Impulse—Clamping bars heated by wires or a ribbon
3.1 Definitions-Refer to Terminology for Geosynthetics,
meltsthesheetsclampedbetweenthem.Acoolingperiodwhile D4439 for definitions of terms applying to this test method.
still clamped allows the polymer to solidify before being
4. Significance and Use
released.
4.1 The use of reinforced geomembranes as barrier materi-
1.3 The types of materials covered by this test method
alshascreatedaneedforastandardtestmethodtoevaluatethe
include, but are not limited to, reinforced geomembranes made
quality of seams produced by thermo-fusion methods.This test
from the following polymers.
method is used for quality control purposes and is intended to
1.3.1 Very Low Density Polyethylene (VLDPE).
provide quality control and quality assurance personnel with
1.3.2 Linear Low Density Polyethylene (LLDPE).
data to evaluate seam quality.
This test method is under the jurisdiction of ASTM Committee D35 on
GeosyntheticsandisthedirectresponsibilityofSubcommitteeD35.10onGeomem- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
branes. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Oct. 1, 2011. Published October 2011. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D7749–11 the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7749 − 11
4.2 Values obtained with this method can be correlated
toD7004.The purpose of correlating these methods was for the
strength of parent material measured in to be comparable to
seam strength measured by the test outlined here. The value
obtained with this method cannot be compared to values for
strip method D7003 for parent material or ASTM DXXXX
strip method for reinforced seams.
5. Apparatus
5.1 Tensile Testing Machine—Constant Rate of Extension
(CRE) equipment meeting the requirements of D76. The load
cell shall be accurate to within +1% of the applied force. The
drive mechanism shall be able to control the rate of extension
to within +1% of the targeted rate. The maximum allowable
error in recorded grip displacement shall be 61% of the
recorded values. The maximum allowable variation in nominal
gage length on repeated return of the clamps to their starting
position shall be less than 0.25 mm (0.
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