1、Designation: D7749 11 (Reapproved 2018)Standard 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 y
2、ear oforiginal adoption 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 contro
3、ltests used to determine 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 the
4、following:1.2.1 Hot 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 surfac
5、es to be seamed by 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.
6、1.2.3 ExtrusionThis 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
7、 factory fabrication.1.2.5 ImpulseClamping bars heated by wires or a ribbonmelt the sheets clamped between them. A cooling 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 g
8、eomembranes madefrom 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 valu
9、es stated in either 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 noncon-formance with the standa
10、rd.1.5 This standard 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to
11、use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarrier
12、s to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D76/D76M Specification for Tensile Testing Machines forTextilesD4439 Terminology for GeosyntheticsD7003/D7003M Test Method for Strip Tensile Properties ofReinforced GeomembranesD7004/D7004M Test Method for Grab Tensile Properties
13、ofReinforced GeomembranesD7747/D7747M Test Method for Determining Integrity ofSeams Produced Using Thermo-Fusion Methods for Re-inforced Geomembranes by the Strip Tensile Method1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subco
14、mmittee D35.10 on Geomem-branes.Current edition approved Feb. 1, 2018. Published February 2018. Originallyapproved in 2011. Last previous edition approved in 2011 as D7749 11. DOI:10.1520/D7749-11R18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servic
15、e at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in acc
16、ordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13. Terminology3.1 DefinitionsR
17、efer to Terminology D4439 for defini-tions 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 use
18、d 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 toTest Method D7004/D7004M. The purpose of correlating thesemethods was for the strength of parent materia
19、l measured inTest Method D7004/D7004M to be comparable to seamstrength measured by the test outlined here. The value obtainedwith this method cannot be compared to values for stripmethod, Test Method D7003/D7003M, for parent material orTest Method D7747/D7747M, strip method for reinforcedseams.5. Ap
20、paratus5.1 Tensile Testing MachineConstant rate of extension(CRE) equipment meeting the requirements of SpecificationD76/D76M. The load cell shall be accurate to within 61%ofthe applied force. The drive mechanism shall be able to controlthe rate of extension to within 61 % of the targeted rate. Them
21、aximum allowable error in recorded grip displacement shallbe 61 % of the recorded values. The maximum allowablevariation in nominal gage length on repeated return of theclamps to their starting position shall be less than 0.25 mm(0.01 in.).5.2 Grip FacesThe clamping force and the clamp surfacesshall
22、 hold the specimen firmly without causing damage.5.2.1 All clamp faces shall be square with sides 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 s
23、hall be cut out with a minimum of 12.5 cm (5 in.) ofmaterial on either side of the seam.6.2 SpecimensFive 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
24、.00 in.) plus the seamwidth in the direction perpendicular to the seam and 102 mm(4.00 in.) in the 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 time
25、required to reach temperature equilibrium may vary accordingto the material type and thickness.7.2 Test ConditionsConduct tests at the standard atmo-sphere for testing geosynthetics, a temperature of 21 6 2C(70 6 4 F) and a relative humidity between 50 to 70 %, unlessotherwise specified.8. Procedure
26、8.1 Set the grip separation equal to the width of the seamplus 76.2 mm (3.00 in.). Set the crosshead speed to305 mm 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 Elonga
27、te the specimen until rupture of reinforcementand coating or until a separation of weld or separation in 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 gri
28、ps or if scrim slip throughthe material held between the grips, discard the individualresult and test another specimen. Slipping scrim may requireincreasing clamping pressure.FIG. 1 Example of Shear TestD7749 11 (2018)28.1.4 Record the load at peak. Record break code (Figs. 3and 4). Only the 1-in. w
29、ide section of seam held directlybetween the grips during testing should be examined for breakcodes.9. Calculations9.1 Seam Grab StrengthSeam grab strength is equal to theaverage of the peak loads for the five specimens. Units shouldbe in N or lbs.NOTE 1Because of the heterogonous nature of reinforc
30、edgeomembranes, calculating force per cross-sectional area is not relevantand should not be done.10. Report10.1 The report shall include the following 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
31、of failure” (Figs. 3 and 4) includes only some of theseam configurations typically found in the industry. When this test methodis applied to seams bonded in configurations other than those identified inFig. 3 or Fig. 4, the users of this test method must agree on applicabledescriptions for modes of
32、specimen rupture.10.1.3 Type of specimen and test.10.1.4 If the specimen does not rupture, report 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 concernin
33、gprecision or bias.FIG. 2 Grab Specimen Test ConfigurationD7749 11 (2018)3FIG. 3 Break Codes for Dual Hot Wedge and Hot Air Seams of Reinforced Geomembranes Tested for Seam Grab StrengthD7749 11 (2018)4FIG. 4 Break Codes for Fillet Extrusion Weld Seams in Reinforced Geomembranes Tested for Seam Grab
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