1、Designation: D4632/D4632M 08 (Reapproved 2013)1Standard Test Method forGrab Breaking Load and Elongation of Geotextiles1This standard is issued under the fixed designation D4632/D4632M; the number immediately following the designation indicates theyear of original adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1NOTEUnits information was editori
3、ally corrected in June 2013.1. Scope1.1 This test method is an index test which provides aprocedure for determining the breaking load (grab strength)and elongation (grab elongation) of geotextiles using the grabmethod. This test method is not suitable for knitted fabrics andalternate test methods sh
4、ould be used. While useful for qualitycontrol and acceptance testing for a specific fabric structure,the results can only be used comparatively between fabricswith very similar structures, because each different fabricstructure performs in a unique and characteristic manner in thistest. The grab tes
5、t methods does not provide all the informationneeded for all design applications and other test methodsshould be used.1.2 Procedures for measuring the breaking load and elon-gation by the grab method in both the dry and wet state areincluded; however, testing is normally done in the dry condi-tion u
6、nless specified otherwise in an agreement or specifica-tion.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningva
7、lues from the two systems may result in non-conformancewith the standard.1.4 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 and health practices and determine
8、the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D76/D76M Specification for Tensile Testing Machines forTextilesD123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing TextilesD2905 Practice for Statements on Number of Spec
9、imens forTextiles (Withdrawn 2008)3D4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products(RECPs) for TestingD4439 Terminology for Geosynthetics3. Terminology3.1 Definitions:3.1.1 atmosphere for testing geotextiles, nair maintainedat a relative humidity of 65 6 5 % relative h
10、umidity andtemperature of 21 6 2C 70 6 4F.3.1.2 breaking load, nthe maximum force applied to aspecimen in a tensile test carried to rupture.3.1.3 cross-machine direction, nthe direction in the planeof the fabric perpendicular to the direction of manufacture.3.1.4 elongation at break, nthe elongation
11、 correspondingto the breaking load, that is, the maximum load.3.1.5 geotextile, nany permeable textile material usedwith foundation, soil, rock, earth, or any other geotechnicalmaterial, as an integral part of a man-made product, structure,or system.3.1.6 grab test, nin fabric testing, a tension tes
12、t in whichonly a part of the width of the specimen is gripped in theclamps.1This test method 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 May 1, 2013. Published June 2013. Or
13、iginallyapproved in 1991. Last previous edition approved in 2008 as D463208. DOI:10.1520/D4632_D4632M-08R13E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the s
14、tandards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.6.1 DiscussionFor example, if the specimen width
15、 is101.6 mm 4 in. and the width of the jaw faces 25.4 mm 1in., the specimen is gripped centrally in the clamps.3.1.7 machine direction, nthe direction in the plane of thefabric parallel to the direction of manufacture.3.1.8 For definitions of other terms used in this test method,refer to Terminology
16、 D123 or Terminology D4439.4. Summary of Test Method4.1 A continually increasing load is applied longitudinallyto the specimen and the test is carried to rupture. Values for thebreaking load and elongation of the test specimen are obtainedfrom machine scales or dials, autographic recording charts, o
17、rinterfaced computers.5. Significance and Use5.1 The grab method is applicable whenever it is desired todetermine the “effective strength” of the fabric in use, that is,the strength of the material in a specific width, together withthe additional strength contributed by adjacent material. Thereis no
18、 simple relationship between grab tests and strip tests sincethe amount of fabric assistance depends on the construction ofthe fabric. It is useful as a quality control or acceptance test.5.2 The procedure in Test Method D4632/D4632M for thedetermination of grab strength of geotextiles may be used f
19、oracceptance testing of commercial shipments, but caution isadvised since information about between-laboratory precisionis incomplete. Comparative tests as directed in 5.2.1 areadvisable.5.2.1 In case of a dispute arising from differences inreported test results when using the procedures in Test Met
20、hodD4632/D4632M for acceptance testing of commercialshipments, the purchaser and the manufacturer should conductcomparative tests to determine if there is a statistical biasbetween their laboratories. Competent statistical assistance isrecommended for the investigation of bias. As a minimum, thetwo
21、parties should take a group of test specimens that are ashomogeneous as possible and which are from a lot of materialof the type in question. The test specimens should then berandomly assigned in equal numbers to each laboratory fortesting. The average results from the two laboratories should becomp
22、ared using the appropriate Students t-test and an accept-able probability level chosen by the two parties before testingis begun. If a bias is found, either its cause must be found andcorrected or the purchaser and the manufacturer must agree tointerpret future test results in the light of the known
23、 bias.5.3 Most geotextile fabrics can be tested by this test method.Some modification of clamping techniques may be necessaryfor a given fabric, depending upon its structure. Specialadaptation may be necessary with strong fabrics, or fabricsmade from glass fibers, to prevent them from slipping in th
24、eclamps or being damaged as a result of being gripped in theclamps, such as cushioning the clamp or boarding the specimenwithin the clamp.5.4 This test method is applicable for testing fabrics eitherdry or wet. It may be used with constant-rate-of-traverse (CRT)or constant-rate-of-extension (CRE) ty
25、pe tension machines.However, there may be no overall correlation between theresults obtained with the CRT machine and the CRE machine.Consequently, these two tension testers cannot be used inter-changeably. In case of controversy, the CRE machine shallprevail.6. Apparatus6.1 Tensile Testing Machine,
26、 of the constant-rate-of-extension (CRE) or constant-rate-of-traverse (CRT) type withautographic recorder conforming to the requirements of Speci-fication D76/D76M.6.2 Clamps, having all gripping surfaces parallel, flat, andcapable of preventing slipping of the specimen during a test.Each clamp shal
27、l have one jaw face measuring 25.4 by 50.8mm 1 by 2 in., with the longer dimension parallel to thedirection of application of the load. The other jaw face of eachclamp shall be at least as large as its mate. Each jaw face shallbe in line, both with respect to its mate in the same clamp andto the cor
28、responding jaw of the other clamp.7. Sampling and Selection7.1 Division into Lots and Lot SamplesDivide the materialinto lots and take a lot sample as directed in Practice D4354.Rolls of fabric are the primary sampling unit.7.2 Laboratory SampleTake for the laboratory sample aswatch extending the wi
29、dth of the fabric and approximately 1m 39.37 in. along the selvage from each roll in the lot sample.The swatch may be taken from the end portion of a rollprovided there is no evidence that it is distorted or differentfrom other portions of the roll. In cases of dispute, take aswatch that will exclud
30、e fabric from the outer wrap of the rollor the inner wrap around the core.7.3 Test SpecimensCut the number of specimens fromeach swatch in the laboratory sample determined as directed inSection 8. Take no specimens nearer the selvage of fabric edgethan120 of the fabric width or 150 mm 6 in., whichev
31、er is thesmaller. Cut rectangular specimens 101.6 by 203.2 mm 4 by 8in. Cut the specimens to be used for grab tests in the machinedirection with the longer dimension parallel to the machinedirection and the specimens to be used for grab tests in thecross-machine direction with the longer dimension p
32、arallel tothe cross-machine direction. Locate each group of specimensalong a diagonal line on the swatch so that each specimen willcontain different warp ends and filling picks. Draw a line 37mm 1.5 in. from the edge of the specimen running its fulllength. For woven and reinforced nonwoven fabrics,
33、this linemust be accurately parallel to the lengthwise yarns in thespecimen.8. Number of Specimens8.1 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 % pr
34、obability level that the test result isno more than 5 % above the true average for each swatch in thelaboratory sample for each the machine and cross-machinedirection, respectively.D4632/D4632M 08 (2013)128.1.1 Reliable Estimate of vWhen there is a reliableestimate of v based upon extensive past rec
35、ords 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 = reliable estimate of the coefficient of variation ofindividual obs
36、ervations on similar materials in theusers laboratory under conditions of single-operatorprecision, %,t = the value of Students t for one-sided limits (see Table1), a 95 % probability level, and the degrees of freedomassociated with the estimate of v, andA = 5.0 % of the average, the value of the al
37、lowablevariation.8.1.2 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 10 specimens forthe machine direction tests and 10 specimens for the cross-machine direction tests. The number of spe
38、cimens is calculatedusing v = 9.5 % of the average for both machine direction andcross-machine direction. These values for v are somewhatlarger than usually found in practice. When a reliable estimateof v for the users laboratory becomes available, Eq 1 willusually require fewer than the fixed numbe
39、r of specimens.9. Conditioning9.1 Bring the specimens to moisture equilibrium in theatmosphere for testing geotextiles. Equilibrium is considered tohave been reached when the increase in mass of the specimenin successive weighings made at intervals of not less than 2 hdoes not exceed 0.1 % of the ma
40、ss of the specimen. In generalpractice, the industry approaches equilibrium from the “asreceived” side.NOTE 1It is recognized that in practice geotextile materials arefrequently not weighed to determine when moisture equilibrium has beenreached. While such a procedure cannot be accepted in cases of
41、dispute,it may be sufficient in routine testing to expose the material to the standardatmosphere for testing for a reasonable period of time before thespecimens are tested. A time of at least 24 h has been found acceptable inmost cases. However, certain fibers may exhibit slow moisture equiliza-tion
42、 rates from the “as received” wet side. When this is known, apreconditioning cycle, as described in Practice D1776, may be agreedupon between contractual parties.9.2 Specimens to be tested in the wet condition shall beimmersed in water maintained at a temperature of 21 6 2C70 6 4F. The time of immer
43、sion must be sufficient towet-out the specimens thoroughly, as indicated by no signifi-cant change in strength or elongation following a longer periodof immersion, and at least 2 min. To obtain thorough wetting,it may be necessary or advisable to add not more than 0.05 %of a nonionic neutral wetting
44、 agent to the water.10. Procedure10.1 Test the conditioned specimens in the standard atmo-sphere for testing in accordance with Section 9.10.2 Set the distance between the clamps at the start of thetest at 75 6 1mm36 0.05 in. Select the load range of thetesting machine such that the maximum load occ
45、urs between10 and 90 % of full-scale load. Set the machine to operate at aspeed of 300 6 10 mm/min 12 6 0.5 in./min.10.3 Secure the specimen in the clamps of the testingmachine, taking care that the long dimension is as nearly aspossible parallel to the direction of application of the load. Besure t
46、hat the tension in the specimen is uniform across theclamped width. Insert the specimen in the clamps so thatapproximately the same length of fabric extends beyond thejaw at each end. Locate the jaws centrally in the widthwisedirection by having the line which was drawn 37 mm 1.5 in.from the edge of
47、 the specimen run adjacent to the side of theupper and lower front jaws which are nearest this edge. Thisensures that the same lengthwise yarns are gripped in bothclamps.10.4 If a specimen slips in the jaws, breaks at the edge of orin the jaws, or if for any reason attributed to a faulty operationth
48、e result falls markedly below the average for the set ofspecimens, discard the result and take another specimen.Continue this procedure until the required number of accept-able breaks have been obtained.NOTE 2The decision to discard a break shall be based on observationof the specimen during the tes
49、t and upon the inherent variability of thefabric. In the absence of other criteria for rejecting a so-called jaw break,any break occurring within 5 mm 14 in. of the jaws which results in avalue below 80 % of the average of all the other breaks shall be discarded.No other break shall be discarded unless it is known to be faulty.NOTE 3It is difficult to determine the precise reason for breakage oftest specimens near the edge of the jaws. If breaks are caused by damageto the specimen by the jaws, then the results should be dis
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