1、Designation: D4885 01 (Reapproved 2011)Standard Test Method forDetermining Performance Strength of Geomembranes bythe Wide Strip Tensile Method1This standard is issued under the fixed designation D4885; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e 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 covers the determination of the perfor-mance strength of synthetic ge
3、omembranes by subjecting widestrips of material to tensile loading.1.2 This test method covers the measurement of tensilestrength and elongation of geomembranes and includes direc-tions for calculating initial modulus, offset modulus, secantmodulus, and breaking toughness.1.3 The basic distinctions
4、between this test method andother methods measuring tensile strength of geomembranes arethe width of the specimens tested and the speed of appliedforce. The greater width of the specimens specified in this testmethod minimizes the contraction edge effect (necking) whichoccurs in many geosynthetics a
5、nd provides a closer relation-ship to actual material behavior in service. The slower speed ofapplied strain also provides a closer relationship to actualmaterial behavior in service.1.4 As a performance test, this method will be used rela-tively infrequently, and to test large lots of material. Thi
6、s testmethod is not intended for routine quality control testing ofgeomembranes.1.5 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with it
7、s 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 Standards:2D76 Specification for Tensile Testing Machines for TextilesD123 Termino
8、logy Relating to TextilesD751 Test Methods for Coated FabricsD882 Test Method for Tensile Properties of Thin PlasticSheetingD1593 Specification for Nonrigid Vinyl Chloride PlasticFilm and SheetingD1909 Standard Table of Commercial Moisture Regains forTextile FibersD4354 Practice for Sampling of Geos
9、ynthetics for TestingD4439 Terminology for Geosynthetics3. Terminology3.1 Definitions:3.1.1 atmosphere for testing geomembranes, nair main-tained at a relative humidity of 50 to 70 % and a temperatureof 21 6 2C (70 6 4F).3.1.1.1 DiscussionWithin the range of 50 to 70 % relativehumidity, moisture con
10、tent is not expected to affect the tensileproperties of geomembrane materials. In addition, geotextilestandard test methods restrict the range of relative humidity to65 6 5 %, while geomembrane standard test methods restrictthe range of relative humidity to 55 6 5 %. The restrictedrange in this test
11、 method is made broader to reduce the need fortesting laboratories to change laboratory conditions, and con-sidering the lack of expected effect of moisture on geomem-branes. The user should consult Table D1909 to resolvequestions regarding moisture regains of textile fibers, espe-cially if the user
12、 is testing a new or unknown material.3.1.2 breaking force, (F), J, nthe force at failure.3.1.3 breaking toughness, T, (FL1), Jm2, nfor geosyn-thetics, the actual work per unit volume of a material corre-sponding to the breaking force.3.1.3.1 DiscussionBreaking toughness is proportional tothe area u
13、nder the force-elongation curve from the origin to thebreaking point (see also, work-to-break). Breaking toughness iscalculated from work-to-break and width of a specimen. Ingeomembranes, breaking toughness is often expressed as forceper unit width of material in inch-pound values. In othermaterials
14、, breaking toughness is often expressed as work perunit mass of material.3.1.4 corresponding force, nsynonym for force at speci-fied elongation.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomem-branes.C
15、urrent edition approved June 1, 2011. Published July 2011. Originally approvedin 1988. Last previous edition approved in 2006 as D4885 06. DOI: 10.1520/D4885-01R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Boo
16、k 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.3.1.5 elastic limit, nin mechanics, the stress intensity atwhich stress and deform
17、ation of a material subjected to anincreasing force cease to be proportional; the limit of stresswithin which a material will return to its original size and shapewhen the force is removed, and hence, not a permanent set.3.1.6 failure, nan arbitrary point beyond which a materialceases to be function
18、ally capable of its intended use.3.1.6.1 DiscussionIn wide strip tensile testing of geosyn-thetics, failure occurs either at the rupture point or at the yieldpoint in the force-elongation curve, whichever occurs first. Forreinforced geomembranes, failure occurs at rupture of thereinforcing fabric. F
19、or nonreinforced geomembranes whichexhibit a yield point, such as polyethylene materials, failureoccurs at the yield point. Even though the geomembranecontinues to elongate, the force-elongation relationship hasbeen irreversibly altered. For nonreinforced geomembraneswhich do not exhibit a yield poi
20、nt, such as plasticized PVCmaterials, failure occurs at rupture of the geomembrane.3.1.7 force at specified elongation, FASE, na force asso-ciated with a specific elongation on the force-elongation curve.(Synonym for corresponding force.)3.1.8 force-elongation curve, nin a tensile test, a graphi-cal
21、 representation of the relationship between the magnitude ofan externally applied force and the change in length of thespecimen in the direction of the applied force. (Synonym forstress-strain curve.)3.1.9 geomembrane, nAn essentially impermeable geo-synthetic used with foundation soil, rock, earth,
22、 or any othergeotechnical engineering related material as an integral part ofa man-made project, structure, or system.3.1.9.1 DiscussionOther names under which geomem-branes are recognized include: flexible membrane liners(fmls), liners, and membranes.3.1.10 index test, na test procedure which may c
23、ontain aknown bias, but which may be used to establish an order for aset of specimens with respect to the property of interest.3.1.11 inflection point, nthe first point of the force-elongation curve at which the second derivative equals zero.3.1.11.1 DiscussionThe inflection point occurs at the firs
24、tpoint on the force-elongation curve at which the curve ceasesto curve upward and begins to curve downward (or vice versa).3.1.12 initial tensile modulus, Ji, (FL1), Nm1, nforgeosynthetics, the ratio of the change in force per unit width tothe change in elongation of the initial portion of a force-e
25、longation curve.3.1.13 offset modulus, Jo, (FL1), Nm1, nfor geosyn-thetics, the ratio of the change in force per unit width to thechange in elongation below an arbitrary offset point at whichthere is a proportional relationship between force and elonga-tion, and above the inflection point on the for
26、ce-elongationcurve.3.1.14 performance test, na test which simulates in thelaboratory as closely as practicable selected conditions expe-rienced in the field and which can be used in design. (Synonymfor design test.)3.1.15 secant modulus, Jsec, (FL1), Nm1, nfor geosyn-thetics, the ratio of change in
27、force per unit width to the changein elongation between two points on a force-elongation curve.3.1.16 tensile, adjcapable of tensions, or relating to ten-sion of a material.3.1.17 tensile modulus, J, (FL1), Nm1, nfor geosynthet-ics, the ratio of the change in tensile force per unit width to acorresp
28、onding change in elongation.3.1.18 tensile strength, nthe maximum resistance to de-formation developed by a specific material when subjected totension by an external force.3.1.19 tensile test, n for geosynthetics, a test in which amaterial is stretched uniaxially to determine the force-elongation ch
29、aracteristics, the breaking force, or the breakingelongation.3.1.20 tension, nthe force that produces a specified elon-gation.3.1.21 wide strip tensile test, n for geosynthetics, a tensiletest in which the entire width of a 200 mm (8.0 in.) widespecimen is gripped in the clamps and the gauge length
30、is100 mm (4.0 in.).3.1.22 work-to-break, W, (LF), J, nin tensile testing, thetotal energy required to rupture a specimen.3.1.22.1 DiscussionFor geomembranes, work-to-break isproportional to the area under the force-elongation curve fromthe origin to the breaking point.3.1.23 yield point, nin geosynt
31、hetics, the point on theforce-elongation curve at which the first derivative equals zero(the first maximum).3.1.24 For definitions of other terms used in this testmethod, refer to Terminologies D123 and D4439.4. Summary of Test Method4.1 A relatively wide specimen is gripped across its entirewidth i
32、n the clamps of a constant rate of extension type tensiletesting machine operated at a prescribed rate of extension,applying a uniaxial load to the specimen until the specimenruptures. Tensile strength, elongation, initial and secant modu-lus, and breaking toughness of the test specimen can becalcul
33、ated from machine scales, dials, recording charts, or aninterfaced computer.5. Significance and Use5.1 This test method is a performance test intended as adesign aid used to determine the ability of geomembranes towithstand the stresses and strains imposed under design con-ditions. This test method
34、assists the design engineer in com-paring several candidate geomembranes under specific testconditions.5.2 As a performance test, this method is not intended forroutine acceptance testing of commercial shipments ofgeomembranes. Other more easily performed test methods,such as Test Methods D751 or Te
35、st Method D882, can be usedfor routine acceptance testing of geomembranes. This testmethod will be used relatively infrequently, and to establishperformance characteristics of geomembrane materials.5.2.1 There is no known correlation between this testmethod and index test methods, such as Test Metho
36、ds D751.5.3 All geomembranes can be tested by this method. Somemodification of techniques may be necessary for a givengeomembrane depending upon its physical make-up. Specialadaptations may be necessary with strong geomembranes orD4885 01 (2011)2geomembranes with extremely slick surfaces, to prevent
37、 themfrom slipping in the clamps or being damaged by the clamps.6. Apparatus6.1 ClampsA gripping system that minimizes (with thegoal of eliminating) slippage, damage to the specimen, anduneven stress distribution. The gripping system shall extend toor beyond the outer edge of the specimen to be test
38、ed.36.2 Specimen CutterAn appropriate cutting device whichdoes not create irregularities or imperfections in the edge of thespecimen. For wide strip specimens, a jig may not be necessaryprovided that the actual cut dimensions of the specimen can bemeasured accurately to the nearest 1.0 mm (0.04 in.)
39、, and thatthe width of the specimen is constant to within 1.0 mm(0.04 in.).6.3 Tensile Testing MachineA testing machine of theconstant rate of extension type as described in SpecificationD76 shall be used. The machine shall be equipped with adevice for recording the tensile force and the amount ofse
40、paration of the grips. Both of these measuring systems shallbe accurate to 62 % and, preferably, shall be external to thetesting machine. The rate of separation shall be uniform andcapable of adjustment within the range of the test.7. Sampling7.1 Lot SampleDivide the product into lots and take thelo
41、t sample as directed in Practice D4354.7.2 Laboratory SampleFor the laboratory sample, take afull-width swatch approximately 1 m (40 in.) long in themachine direction from each roll in the lot sample. The samplemay be taken from the end portion of a roll provided there isno evidence it is distorted
42、or different from other portions ofthe roll.7.3 Test SpecimensTake a total of twelve specimens fromeach swatch in the laboratory sample, with six specimens fortests in the machine direction and six specimens for tests in thecross-machine direction. Take the specimens from a diagonalon the swatch wit
43、h no specimen nearer the edge of thegeomembrane than 1/10 of the width of the geomembrane. Cuteach specimen 200 mm (8.0 in.) wide by at least 200 mm(8.0 in.) long with the length precisely aligned with thedirection in which the specimen is to be tested. The specimensmust be long enough to extend com
44、pletely through both clampsof the testing machine. Draw two parallel lines near the centerof each specimen length that (1) are separated by 100 mm (4.0in.), (2) extend the full width of the specimen, and (3) areexactly perpendicular to the length of the specimen. Exercisethe utmost care in selecting
45、, cutting, and preparing specimensto avoid nicks, tears, scratches, folds, or other imperfectionsthat are likely to cause premature failure.8. Conditioning8.1 Expose the specimens to the standard atmosphere fortesting geomembranes for a period long enough to allow thegeomembrane to reach equilibrium
46、 with the standard atmo-sphere. Consider the specimen to be at moisture equilibriumwhen the change in mass of the specimen in successiveweighings made at intervals of not less than 2 h does notexceed 0.1 % of the mass of the specimen. Consider thespecimen to be at temperature equilibrium after1hofex
47、posureto the standard atmosphere for testing.9. Procedure9.1 Test adequately conditioned specimens. Conduct tests ata temperature of 21 6 2C (70 6 4F) and at a relativehumidity of 50 to 70 %. The engineer may specify additionaltemperatures based upon expected service conditions for theinstallation.9
48、.2 Measure for the specimens thickness at the four cornersof the specimen. Select specimens used in this procedure sothat thickness is uniform to within 5 %. Measure thicknessusing either Specification D1593 for nonreinforced geomem-branes or Test Methods D751 for reinforced geomembranes.9.3 Positio
49、n the grips of the testing apparatus to a separationof 100 6 3mm(46 0.1 in.). At least one clamp should besupported by a free swivel or universal joint which will allowthe clamp to rotate in the plane of the fabric. Select the forcerange of the testing machine so that the break occurs between10 and 90 % of full scale load. Set the machine to a strain rateas directed in 9.6.9.4 Mount the specimen centrally in the clamps. Do this byhaving the two lines, which were previously drawn 100 63 mm (4.0 6 0.1 in.) apart across the width of the
