1、Designation: D6637 11Standard Test Method forDetermining Tensile Properties of Geogrids by the Single orMulti-Rib Tensile Method1This standard is issued under the fixed designation D6637; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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 tensilestrength properties of geogrids by subjecting
3、 strips of varyingwidth to tensile loading.1.2 Three alternative procedures are provided to determinethe tensile strength, as follows:1.2.1 Method ATesting a single geogrid rib in tension (Nor lbf).1.2.2 Method BTesting multiple geogrid ribs in tension(kN/m or lbf/ft).1.2.3 Method CTesting multiple
4、layers of multiplegeogrid ribs in tension (kN/m or lbf/ft).1.3 This test method is intended for quality control andconformance testing of geogrids.1.4 The values stated in SI units are to be regarded as thestandard. The inch-pound values stated in parentheses areprovided for information only.1.5 Thi
5、s standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the ap
6、plicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD1909 Standard Table of Commercial Moisture Regains forTextile FibersD4354 Practice for Sampling of Geosynthet
7、ics for TestingD4439 Terminology for GeosyntheticsD5262 Test Method for Evaluating the Unconfined TensionCreep and Creep Rupture Behavior of Geosynthetics3. Terminology3.1 Definitions:3.1.1 atmosphere for testing geosynthetics, nair main-tained at a relative humidity of 50 to 70 % and a temperatureo
8、f 21 6 2C (70 6 4F).3.1.2 breaking force, (F), nthe force at failure.3.1.3 corresponding force, nsynonym for force at speci-fied elongation.3.1.4 force at specified elongation, FASE, na force asso-ciated with a specific elongation on the force-elongation curve(synonym for corresponding force.)3.1.5
9、force-elongation curve, nin a tensile test, a graphi-cal 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.)3.1.6 geogrid, na geosynthetic formed by a re
10、gular net-work of integrally connected elements with aperetures greaterthan 6.35 mm (14 in.) to allow interlocking with surroundingsoil, rock, earth, and other surrounding materials to primarilyfunction as reinforcement. D52623.1.7 geosynthetic, na product manufactured from poly-meric material used
11、with soil, rock, earth, or other geotechnicalengineering related material as an integral part of a man madeproject, structure, or system.3.1.8 index test, na test procedure which may containknown bias, but which may be used to establish an order for aset of specimens with respect to the property of
12、interest.3.1.9 integral, adjin geosynthetics, forming a necessarypart of the whole; a constituent.3.1.10 junction, nthe point where geogrid ribs are inter-connected to provide structure and dimensional stability.3.1.11 rib, nfor geogrids, the continuous elements of ageogrid which are interconnected
13、to a node or junction.3.1.12 rupture, nfor geogrids, the breaking or tearingapart of ribs.3.1.13 tensile, adjcapable of tensions, or relating to ten-sion of a material.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D
14、35.01 on Mechani-cal Properties.Current edition approved Oct. 1, 2011. Published October 2011. Originallyapproved in 2001. Last previous edition approved in 2010 as D663701(2010).DOI: 10.1520/D6637-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servi
15、ce at serviceastm.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.3.1.14 tensile strength, (af), nfor geogrids
16、the maximumresistance to deformation developed for a specific materialwhen subjected to tension by an external force. Tensile strengthof geogrids is the characteristic of a sample as distinct from aspecimen and is expressed in force per unit width.3.1.15 tensile test, nfor geosynthetics, a test in w
17、hich amaterial is stretched uniaxially to determine the force-elongation characteristics, the breaking force, or the breakingelongation.3.1.16 tension, nthe force that produces a specified elon-gation.3.2 For definitions of other terms used in this test method,refer to Terminologies D123 and D4439.4
18、. Summary of Test Method4.1 Method AIn this method, a single, representative ribspecimen of a geogrid is clamped and placed under a tensileforce using a constant rate of extension testing machine. Thetensile force required to fail (rupture) the specimen is recorded.The ultimate single rib tensile st
19、rength (N or lbf) is thendetermined based on the average of six single rib tensile tests.4.2 Method BA relatively wide specimen is grippedacross its entire width in the clamps of a constant rate ofextension type tensile testing machine operated at a prescribedrate of extension, applying a uniaxial l
20、oad to the specimen untilthe specimen ruptures. Tensile strength (kN/m or lbf/ft),elongation, and secant modulus of the test specimen can becalculated from machine scales, dials, recording charts, or aninterfaced computer.4.3 Method CA relatively wide, multiple layered speci-men is gripped across it
21、s entire width in the clamps of aconstant rate of extension type tensile testing machine operatedat a prescribed rate of extension, applying a uniaxial load to thespecimen until the specimen ruptures. Tensile strength (kN/mor lbf/ft), elongation and secant modulus of the test specimencan be calculat
22、ed from machine scales, dials recording charts,or an interfaced computer.5. Significance and Use5.1 The determination of the tensile force-elongation valuesof geogrids provides index property values. This test methodshall be used for quality control and acceptance testing ofcommercial shipments of g
23、eogrids.5.2 In cases of dispute arising from differences in reportedtest results when using this test method for acceptance testingof commercial shipments, the purchaser and supplier shouldconduct comparative tests to determine if there is a statisticalbias between their laboratories. Competent stat
24、istical assis-tance is recommended for the investigation of bias. As aminimum, the two parties should take a group of test speci-mens which are as homogeneous as possible and which arefrom a lot of material of the type in question. The testspecimens should then be randomly assigned in equal numberst
25、o each laboratory for testing. The average results from the twolaboratories should be compared using Students t-test forunpaired data and an acceptable probability level chosen by thetwo parties before the testing began. If a bias is found, either itscause must be found and corrected or the purchase
26、r andsupplier must agree to interpret future test results in light of theknown bias.5.3 All geogrids can be tested by any of these methods.Some modification of techniques may be necessary for a givengeogrid depending upon its physical make-up. Special adapta-tions may be necessary with strong geogri
27、ds, multiple layeredgeogrids, or geogrids that tend to slip in the clamps or thosewhich tend to be damaged by the clamps.6. Apparatus6.1 Testing ClampsThe clamps shall be sufficiently wideto grip the entire width of the specimen (as determined by thetest method) and with appropriate clamping power t
28、o preventslipping or crushing (damage). For a given product, the sameclamps shall be used in testing methods A, B, and C prior tomaking any comparison between results.6.1.1 Size of Jaw FacesEach clamp shall have jaw facesmeasuring wider than the width of the specimen.6.2 Tensile Testing MachineA tes
29、ting 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 ofseparation of the grips. Both of these measuring systems shallbe accurate to 6 1.0 % and, preferably, shall b
30、e external to thetesting machine. The rate of separation shall be uniform andcapable of adjustment within the range of the test.6.3 Distilled Water and Nonionic Wetting Agent, shall beused for wet specimens only.6.4 ExtensometerWhen required by the method, a devicecapable of measuring the distance b
31、etween two referencepoints on the specimen without any damage to the specimen orslippage, care being taken to ensure that the measurementrepresents the true movement of the reference points. Ex-amples of extensometers include mechanical, optical, infraredor electrical devices.7. Sampling7.1 Lot Samp
32、leDivide the product into lots and take thelot sample as directed in Practice D4354.7.2 Laboratory SampleFor the laboratory sample, take afull roll width swatch long enough in the machine directionfrom each roll in the lot sample to ensure that the requirementsin 8.1 can be met. The sample may be ta
33、ken from the endportion of a roll provided there is no evidence it is distorted ordifferent from other portions of the roll.8. Test Specimen8.1 The specimens shall consist of three (3) junctions or 300mm in length (12 in.), in order to establish a minimumspecimen length in the direction of the test
34、(either the machineor cross-machine direction). All specimens should be free ofsurface defects, etc., not typical of the laboratory sample. Takeno specimens nearer the selvage edge along the geogrid than110 the width of the sample.NOTE 1If a comparison of one geogrid to another is to be made theleng
35、th of each specimen shall be the same (as similar as possibly) andagreed upon by all parties.D6637 1128.2 Preparation:8.2.1 Method APrepare each finished specimen, as shownin Fig. 1, to contain one rib in the cross-test wide by at leastthree junctions (two apertures) long in the direction of thetest
36、ing, with the length dimension being designated and accu-rately cut parallel to the direction for which the tensile strengthis being measured.8.2.2 Method BPrepare each finished specimen, as shownin Fig. 2, to be a minimum of 200 mm wide and contain fiveribs in the cross-test direction wide by at le
37、ast three junctions(two apertures) or 300 mm (12 in.) long in the direction of thetesting, with the length dimension being designated and accu-rately cut parallel to the direction for which the tensile strengthis being measured.8.2.3 Method CPrepare each finished specimen, as shownin Fig. 2, to be a
38、 minimum of 200 mm wide and contain fiveribs in the cross-test direction wide by at least three junctions(two apertures) or 300 mm (12 in.) long in the direction of thetesting, with the length dimension being designated and accu-rately cut parallel to the direction for which the tensile strengthis b
39、eing measured. This must be repeated for each layer ofgeogrid included in the test.8.2.4 Within Test Methods A, B, and C, the outermost ribsare commonly cut prior to testing to permit extra width ofmaterial in the clamps to minimize slippage within the clamps.If this procedure causes nonuniform dist
40、ribution of load to thegauge length area of the specimen, the same width of materialshall be included in the clamps as will be tested in the gaugelength area. In either case, the test results shall be based on theunit of width associated with the number of intact ribs.8.3 Number of Test Specimens:8.
41、3.1 Unless otherwise agreed upon as when provided in anapplicable material specification, take a number of test speci-mens per swatch in the laboratory sample such that the usermay expect at the 95 % probability level that the test result isno more than 5 % above the true average for each swatch in
42、thelaboratory sample for each required direction, see Note 2.NOTE 2In some applications, it may be necessary to perform tensiletests in both the machine and the cross-machine directions. In all cases, thedirection of the tensile test specimen(s) should be clearly noted.8.3.2 Reliable Estimate of vWh
43、en there is a reliableestimate of v based upon extensive past records for similarmaterials tested in the users laboratory as directed in themethod, calculate the required number of specimens using Eq1, as follows:n 5 tv/A!2(1)where:n = number of test specimens (rounded upward to a wholenumber),v = r
44、eliable estimate of the coefficient of variation ofindividual observations on similar materials in theusers laboratory under conditions of single-operatorprecision, %,t = the value of Students t for one-sided limits, a 95 %probability level, and the degrees of freedom associ-ated with the estimate o
45、f v, and;A = 5.0 % of the average, the value of allowable variation.8.3.3 No Reliable Estimate of vWhen there is no reliableestimate of v for the users laboratory, Eq 1 should not be useddirectly. Instead, specify the fixed number of 5 specimens forthe required direction. The number of specimens is
46、calculatedusing v = 9.5 % of the average for the required direction. Thisvalue for v is somewhat larger than usually found in practice.When a reliable estimate of v for the users laboratory becomesavailable, Eq 1 will usually require fewer than the fixednumber of specimens.9. Conditioning9.1 Expose
47、the specimens to the atmosphere for testinggeosynthetics for a period long enough to allow the geogrid toreach equilibrium within this standard atmosphere. Considerthe specimen to be at moisture equilibrium when the change inmass of the specimen in successive weighings made at inter-vals of not less
48、 than 2 h does not exceed 0.1 % of the mass ofthe specimen. Consider the specimen to be at temperatureequilibrium after1hofexposure to the atmosphere for testinggeosynthetics.9.2 Specimens to be tested in the wet condition shall beimmersed in water for a minimum of one hour, maintained ata temperatu
49、re of 21 6 2C (70 6 4F). The time of immersionmust be sufficient to wet-out the specimens thoroughly, asindicated by no significant change in strength or elongationfollowing a longer period of immersion, and at least 2 min. Toobtain thorough wetting, it may be necessary or advisable touse distilled water.9.3 Geogrids may be received in the laboratory rolled, thusit is important to flatten the specimens to avoid misleadingelongation measurements. Geogrids which exhibit curlmemory should be laid flat and weighted, until the geogridremains
