1、Designation: D7749 11Standard Test Method forDetermining Integrity of Seams Produced Using Thermo-Fusion Methods for Reinforced Geomembranes by the GrabMethod1This standard is issued under the fixed designation D7749; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes destructive quality controltests used to det
3、ermine the integrity of thermo-fusion seamsmade with reinforced geomembranes. A test procedure isdescribed that uses seam tests using grab specimens for seamshear strength.1.2 The types of thermal field and factory seaming tech-niques used to construct geomembrane seams include thefollowing.1.2.1 Ho
4、t AirThis technique introduces high-temperatureair between two geomembrane surfaces to facilitate melting.Pressure is applied to the top or bottom geomembrane, forcingtogether the two surfaces to form a continuous bond.1.2.2 Hot WedgeThis technique melts the two geomem-brane surfaces to be seamed by
5、 running a hot metal wedgebetween them. Pressure is applied to the top and bottomgeomembrane to form a continuous bond. Some seams of thiskind are made with dual tracks separated by a non-bonded gap.These seams are sometimes referred to as dual hot wedgeseams or double-track seams.1.2.3 ExtrusionThi
6、s technique encompasses extrudingmolten resin between two geomembranes or at the edge of twooverlapped geomembranes to effect a continuous bond.1.2.4 Radio Frequency (RF) or DielectricHigh frequencydielectric equipment is used to generate heat and pressure toform an overlap seam in factory fabricati
7、on.1.2.5 ImpulseClamping bars heated by wires or a ribbonmelts the sheets clamped between them.Acooling period whilestill clamped allows the polymer to solidify before beingreleased.1.3 The types of materials covered by this test methodinclude, but are not limited to, reinforced geomembranes madefro
8、m 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 UnitsThe values stated in either
9、 SI units or inch-pound units are to be regarded separately as standard. Thevalues 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 standar
10、d does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM
11、 Standards:2D4439 Terminology for GeosyntheticsD7004 Test Method for Grab Tensile Properties of Rein-forced GeomembranesD7003 Test Method for Strip Tensile Properties of Rein-forced GeomembranesD76 Specification for Tensile Testing Machines for Textiles3. Terminology3.1 Definitions-Refer to Terminol
12、ogy for Geosynthetics,D4439 for definitions of terms applying to this test method.4. Significance and Use4.1 The use of reinforced geomembranes as barrier materi-als has created a need for a standard test method to evaluate thequality of seams produced by thermo-fusion methods. This testmethod is us
13、ed for quality control purposes and is intended toprovide quality control and quality assurance personnel withdata to evaluate seam quality.4.2 Values obtained with this method can be correlated toD7004. The purpose of correlating these methods was for the1This test method is under the jurisdiction
14、of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomem-branes.Current edition approved Oct. 1, 2011. Published October 2011. DOI: 10.1520/D7749112For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at s
15、erviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.strength of parent material measured in D7004 to be
16、compa-rable to seam strength measured by the test outlined here. Thevalue obtained with this method cannot be compared to valuesfor strip method D7003 for parent material or ASTM DXXXXstrip method for reinforced seams.5. Apparatus5.1 Tensile Testing MachineConstant Rate of Extension(CRE) equipment m
17、eeting the requirements of D76. The loadcell shall be accurate to within +1% of the applied force. Thedrive mechanism shall be able to control the rate of extensionto within +1% of the targeted rate. The maximum allowableerror in recorded grip displacement shall be 61% of therecorded values. The max
18、imum allowable variation in nominalgage length on repeated return of the clamps to their startingposition shall be less than 0.25 mm (0.01 in.).5.2 Grip FacesThe clamping force and the clamp sur-faces shall hold the specimen firmly without causing damage.5.2.1 All clamp faces shall be square with si
19、des 25.4 mm(1.00 in.). By aligning the grips, an area of approximately onesquare inch shall be held in each clamp.6. Sample and Specimen Preparation6.1 Seam SamplesApproximately 1 m (36 in) length ofseam shall be cut out with a minimum of 12.5 cm (5 in) ofmaterial on either side of the seam.6.2 Spec
20、imensFive specimens. The locations from whichthe specimens are taken shall be spaced evenly along the lengthof the seam sample. Rectangular test specimens as shown inFig. 2 shall be a minimum of 203 mm (8.00 in) plus the seamwidth in the direction perpendicular to the seam and 102 mm(4.00 in) in the
21、 dimension parallel to the seam. The seamshould be centered in the specimen.7. Conditioning7.1 ConditioningSpecimens may be tested once they haveequilibrated at standard laboratory temperature. The timerequired to reach temperature equilibrium may vary accordingto the, material type and thickness.7.
22、2 Test ConditionsConduct tests at the standard atmo-sphere for testing geosynthetics, a temperature of 2162C(7064F) and a relative humidity between 50% to 70%, unlessotherwise specified.8. Procedure8.1 Set the grip separation equal to the width of the seamplus 76.2 mm (3.00 in). Set the crosshead sp
23、eed to 305mm/min (12 in/min).8.1.1 Place the specimen symmetrically in the clamps so theweld will experience shear force (Fig. 1). Center the seamvertically between the grips (Fig. 2).8.1.2 Elongate the specimen until rupture of reinforcementand coating or until a separation of weld or separation in
24、 planehas occurred across the entire weld in at least one locationacross the narrow dimension of the specimen. See Fig. 3 forexplanation of separation in plane.8.1.3 If a specimen slips in the grips or if scrim slip throughthe material held between the grips, discard the individualresult and test an
25、other specimen. Slipping scrim may requireincreasing clamping pressure.8.1.4 Record the load at peak. Record Break Code (Fig. 3and Fig. 4). Only the 1 in.wide section of seam held directlybetween the grips during testing should be examined for BreakCodes.9. Calculations9.1 Seam Grab Strength:Seam gr
26、ab strength is equal to the average of the peak loadsfor the 5 specimens. Units should be in N or lbs.NOTE 1Because of the heterogonous nature of a reinforced geomem-branes, calculating force per cross-sectional area is not relevant andshould not be done.10. Report10.1 The report shall include the f
27、ollowing information.10.1.1 Peak load for individual specimens and average in Nor lbs.10.1.2 Individual location of break code for each specimen.NOTE 2“Locus-of-Failure” (Fig. 3 and Fig. 4) include only some ofFIG. 1 Example of shear testD7749 112the typically found seam configurations found in the
28、industry. When thistest method is applied to seams bonded in configurations other than thoseidentified in Fig. 3 or Fig. 4, the users of this test method must agree onapplicable descriptions for modes of specimen rupture.10.1.3 Type of specimen and test.10.1.4 If the specimen does not rupture, repor
29、t this and themaximum extension achieved during the test.10.1.5 Report the grip separation and crosshead speed usedin the testing.11. Precision and Bias11.1 No statement can be made at this time concerningprecision or bias.FIG. 2 Grab specimen test configurationD7749 113FIG. 3 Break Codes for dual h
30、ot wedge and hot air seams of reinforced geomembranes tested for seam grab strength.D7749 114FIG. 4 Break codes for fillet extrusion weld seams in reinforced geomembranes tested for seam grab strength.D7749 115ASTM International takes no position respecting the validity of any patent rights asserted
31、 in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the
32、 responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive c
33、areful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Internati
34、onal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D7749 116
