1、Designation: D 6637 01Standard Test Method forDetermining Tensile Properties of Geogrids by the Single orMulti-Rib Tensile Method1This standard is issued under the fixed designation D 6637; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the determination of thetensile strength properties of geogrids by subjec
3、ting strips ofvarying width 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 multi
4、ple layers of multiple geo-grid 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、5 This 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 t
6、he applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 76 Specifications for Tensile Testing Machines for Tex-tiles2D 123 Terminology Relating to Textiles2D 1909 Table of Commercial Moisture Regains for TextileFibers2D 4354 Practice for Sampling of Geosyn
7、thetics for Testing3D 4439 Terminology for Geosynthetics33. Terminology3.1 Definitions:3.1.1 atmosphere for testing geosynthetics, nair main-tained at a relative humidity of 50 to 70 % and a temperatureof 21 6 2C (70 6 4F).3.1.2 breaking force, (F), nthe force at failure.3.1.3 corresponding force, n
8、synonym 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 force-elongation curve, nin a tensile test, a graphi-cal representation of the relationship betw
9、een 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 regular net-work of integrally connected elements with aperetures greaterthan 6.35 mm (14 inch) t
10、o allow interlocking with surroundingsoil, rock, earth, and other surrounding materials to primarilyfunction as reinforcement. (D 5262)3.1.7 integral, adjin geosynthetics, forming a necessarypart of the whole; a constituent.3.1.8 geosynthetic, na product manufactured from poly-meric material used wi
11、th soil, rock, earth, or other geotechnicalengineering related material as an integral part of a man madeproject, structure, or system.3.1.9 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 in
12、terest.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 either in the machine or cross-machinedirection as manufactured.3.1.12 rupture, nfor geogrids, the breaki
13、ng or tearingapart of ribs.3.1.13 tensile, adjcapable of tensions, or relating to ten-sion of a material.3.1.14 tensile strength, (af), nfor geogrids the maximumresistance to deformation developed for a specific materialwhen subjected to tension by an external force. Tensile strengthof geogrids is t
14、he 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 which amaterial is stretched uniaxially to determine the force-elongation characteristics, the breaking force, or the breakingelongation.1This test met
15、hod is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-cal Properties.Current edition approved Feb. 10, 2001. Published May 2001.2Annual Book of ASTM Standards, Vol 07.01.3Annual Book of ASTM Standards, Vol 04.09.1Copyri
16、ght ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.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 D 123 and D 4439.4. Summary of Test Method4.1 Method AIn this method, a
17、 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 strength (N or lbf) is thendetermined based on the aver
18、age 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 load to the specimen untilthe specimen ruptures. Tensi
19、le 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 its entire width in the clamps of aconstant rate of ext
20、ension 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 calculated from machine scales, dials recording charts,or an
21、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 geogrids.5.2 In cases of dispute arising from differen
22、ces 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 statistical assis-tance is recommended for the investigat
23、ion 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 numbersto each laboratory for testing. The average results fr
24、om 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 purchaser andsupplier must agree to interpret future test res
25、ults 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 geogrids, multiple layeredgeogrids, or geogrids that tend t
26、o 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 to preventslipping or crushing (damage). For a given p
27、roduct, 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 testing machine of theconstant rate of extension type as
28、 described in SpecificationD 76 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 be external to thetesting machine. The rate of separa
29、tion 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 between two referencepoints on the specimen without a
30、ny 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 SampleDivide the product into lots and take thelot sampl
31、e as directed in Practice D 4354.7.2 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 taken from the endportion of a roll provided there is
32、 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 (either the machineor cross-machine direction). All
33、 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 thelength of each specimen shall be the same (as similar a
34、s possibly) andagreed upon by all parties.8.2 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 thetesting, with the length dimension being designated and accu-rat
35、ely 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 least three junctions(two apertures) or 300 mm (12 in.) long i
36、n the direction of theD 66372testing, 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 minimum of 200 mm wide and contain fiveribs in the c
37、ross-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 being measured. This must be repeated for each layer o
38、fgeogrid included in the test.8.2.4 Within test methods A, B and C the outermost ribs arecut prior to testing to prevent slippage from occurring withinthe clamps. For those cases where the outermost ribs aresevered, the test results shall be based on the unit of widthassociated with the number of in
39、tact ribs.8.3 Number of Test Specimens:8.3.1 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 % a
40、bove the true average for each swatch in 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 cle
41、arly noted.8.3.2 Reliable Estimate of vWhen 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 specimen
42、s (rounded upward to a wholenumber),v = reliable 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 o
43、f freedom associ-ated with the estimate of 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 requir
44、ed direction. The number of specimens is 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 fixednumbe
45、r of specimens.9. Conditioning9.1 Expose 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
46、 weighings made at inter-vals of not less 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 mini
47、mum of one hour, maintained ata temperature 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 b
48、e 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 flat without wei
49、ght.10. Procedure10.1 Zero the testing system.10.2 Machine Set-Up ConditionsAt the start of the test,adjust the distance between the clamps or the distance fromcenterline to centerline of rollers to the greater distance of threejunctions or 200 6 3 mm (8.0 6 0.1 in.), such that at least onetransverse rib is contained centrally within the gage length. Atleast one clamp should be supported by a free swivel oruniversal joint which will allow the clamp to rotate in the planeof the geogrid. Select the force range of the testing machine sothe brea
