Designation:D7749−11StandardTestMethodforDeterminingIntegrityofSeamsProducedUsingThermo-FusionMethodsforReinforcedGeomembranesbytheGrabMethod1ThisstandardisissuedunderthefixeddesignationD7749;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethoddescribesdestructivequalitycontroltestsusedtodeterminetheintegrityofthermo-fusionseamsmadewithreinforcedgeomembranes.Atestprocedureisdescribedthatusesseamtestsusinggrabspecimensforseamshearstrength.1.2Thetypesofthermalfieldandfactoryseamingtech-niquesusedtoconstructgeomembraneseamsincludethefollowing.1.2.1HotAir—Thistechniqueintroduceshigh-temperatureairbetweentwogeomembranesurfacestofacilitatemelting.Pressureisappliedtothetoporbottomgeomembrane,forcingtogetherthetwosurfacestoformacontinuousbond.1.2.2HotWedge—Thistechniquemeltsthetwogeomem-branesurfacestobeseamedbyrunningahotmetalwedgebetweenthem.Pressureisappliedtothetopandbottomgeomembranetoformacontinuousbond.Someseamsofthiskindaremadewithdualtracksseparatedbyanon-bondedgap.Theseseamsaresometimesreferredtoasdualhotwedgeseamsordouble-trackseams.1.2.3Extrusion—Thistechniqueencompassesextrudingmoltenresinbetweentwogeomembranesorattheedgeoftwooverlappedgeomembranestoeffectacontinuousbond.1.2.4RadioFrequency(RF)orDielectric—Highfrequencydielectricequipmentisusedtogenerateheatandpressuretoformanoverlapseaminfactoryfabrication.1.2.5Impulse—Clampingbarsheatedbywiresoraribbonmeltsthesheetsclampedbetweenthem.Acoolingperiodwhilestillclampedallowsthepolymertosolidifybeforebeingreleased.1.3Thetypesofmaterialscoveredbythistestmethodinclude,butarenotlimitedto,reinforcedgeomembranesmadefromthefollowingpolymers.1.3.1VeryLowDensityPolyethylene(VLDPE).1.3.2LinearLowDensityPolyethylene(LLDPE).1.3.3FlexiblePolypropylene(fPP).1.3.4PolyvinylChloride(PVC).1.3.5Chl...
