1、Designation: D4632/D4632M 15aStandard 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 revision, the year of las
2、t 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 U.S. Department of Defense.1. Scope1.1 This test method is an index test w
3、hich 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 should be used. While useful for qualitycontrol and acceptance testing for a
4、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 test methods does not provide all the informationneeded for all design applica
5、tions 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 unless specified otherwise in an agreement or specifica-tion.1.3 The values
6、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. Combiningvalues from the two systems may result in non-conformancewith the standard.1.
7、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 the applica-bility of regulatory limitations prior to use.2. Referenced Doc
8、uments2.1 ASTM Standards:2D76/D76M Specification for Tensile Testing Machines forTextilesD123 Terminology Relating to TextilesD1776/D1776M Practice for Conditioning and Testing Tex-tilesD2905 Practice for Statements on Number of Specimens forTextiles (Withdrawn 2008)3D4354 Practice for Sampling of G
9、eosynthetics and RolledErosion Control Products(RECPs) for TestingD4439 Terminology for GeosyntheticsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions:
10、3.1.1 atmosphere for testing geotextiles, nair maintainedat a relative humidity of 65 6 5 % relative humidity 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 plane
11、of the fabric perpendicular to the direction of manufacture.3.1.4 elongation at break, nthe elongation 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 integ
12、ral part of a man-made product, structure,or system.3.1.6 grab test, nin fabric testing, a tension test in whichonly a part of the width of the specimen is gripped in theclamps.3.1.6.1 DiscussionFor example, if the specimen width is101.6 mm 4 in. and the width of the jaw faces 25.4mm 1 in., the spec
13、imen is gripped centrally in the clamps.3.1.7 machine direction, nthe direction in the plane of thefabric parallel to the direction of manufacture.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-cal
14、Properties.Current edition approved May 15, 2015. Published June 2015. Originallyapproved in 1991. Last previous edition approved in 2015 as D4632/D4632M15.DOI: 10.1520/D4632_D4632M-15A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceas
15、tm.org. For Annual Book of ASTMStandards volume information, refer to the standards 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 194
16、28-2959. United States13.1.8 For definitions of other terms used in this test method,refer to Terminology 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
17、elongation of the test specimen are obtainedfrom machine scales or dials, autographic recording charts, orinterfaced 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 materi
18、al in a specific width, together withthe additional strength contributed by adjacent material. Thereis no 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
19、 procedure in Test Method D4632/D4632M for thedetermination of grab strength of geotextiles may be used foracceptance 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
20、 case of a dispute arising from differences inreported test results when using the procedures in Test MethodD4632/D4632M for acceptance testing of commercialshipments, the purchaser and the manufacturer should conductcomparative tests to determine if there is a statistical biasbetween their laborato
21、ries. Competent statistical assistance isrecommended for the investigation of bias. As a minimum, thetwo 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
22、 equal numbers to each laboratory fortesting. The average results from the two laboratories should becompared 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 o
23、r the purchaser and the manufacturer must agree tointerpret future test results in the light of the known 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 ma
24、y be necessary with strong fabrics, or fabricsmade from glass fibers, to prevent them from slipping in theclamps 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 ei
25、therdry or wet. It may be used with constant-rate-of-traverse (CRT)or constant-rate-of-extension (CRE) type 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-
26、changeably. In case of controversy, the CRE machine shallprevail.6. Apparatus6.1 Tensile Testing Machine, 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
27、 surfaces parallel, flat, andcapable of preventing slipping of the specimen during a test.Each clamp shall 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
28、as its mate. Each jaw face shallbe in line, both with respect to its mate in the same clamp andto the corresponding 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 a
29、re the primary sampling unit.7.2 Laboratory SampleTake for the laboratory sample aswatch extending the width of the fabric and approximately1 m 39.37 in. along the selvage from each roll in the lotsample. The swatch may be taken from the end portion of a rollprovided there is no evidence that it is
30、distorted or differentfrom other portions of the roll. In cases of dispute, take aswatch that will exclude 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
31、. Take no specimens nearer the selvage of fabric edgethan120 of the fabric width or 150 mm 6 in., whichever is thesmaller. Cut rectangular specimens 101.6 by 203.2mm 4 by 8 in. Cut the specimens to be used for grab tests inthe machine direction with the longer dimension parallel to themachine direct
32、ion and the specimens to be used for grab testsin the cross-machine direction with the longer dimensionparallel to the cross-machine direction. Locate each group ofspecimens along a diagonal line on the swatch so that eachspecimen will contain different warp ends and filling picks.Draw a line 37 mm
33、1.5 in. from the edge of the specimenrunning its full length. For woven and reinforced nonwovenfabrics, this line must be accurately parallel to the lengthwiseyarns in the specimen.8. Number of Specimens8.1 Unless otherwise agreed upon as when provided in anapplicable material specification, take a
34、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 thelaboratory sample for each the machine and cross-machinedirection, respectively.8.1.1 Reliable
35、 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)D4632/D4632M 15a2where:n = number of test specimens (round
36、ed upward to a wholenumber),v = reliable estimate of the coefficient of variation of indi-vidual observations on similar materials in the userslaboratory under conditions of single-operatorprecision, %,t = the value of Students t for one-sided limits (see Table1), a 95 % probability level, and the d
37、egrees of freedomassociated with the estimate of v, andA = 5.0 % of the average, the value of the allowablevariation.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 fort
38、he machine direction tests and 10 specimens for the cross-machine direction tests. The number of specimens 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 estimate
39、of v for the users laboratory becomes available, Eq 1 willusually require fewer than the fixed number 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 s
40、pecimenin successive weighings made at intervals of not less than 2 hdoes not exceed 0.1 % of the mass 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 determi
41、ne when moisture equilibrium has beenreached. While such a procedure cannot be accepted in cases of 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
42、 been found acceptable inmost cases. However, certain fibers may exhibit slow moisture equaliza-tion rates from the “as received” wet side. When this is known, apreconditioning cycle, as described in Practice D1776/D1776M, may beagreed upon between contractual parties.9.2 Specimens to be tested in t
43、he wet condition shall beimmersed in water maintained at a temperature of 21 6 2C70 6 4F. The time of immersion 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
44、 thorough wetting,it may be necessary or advisable to add not more than 0.05 %of a nonionic neutral wetting 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 o
45、f thetest at 75 6 1mm36 0.05 in. Select the load range of thetesting machine such that the maximum load occurs 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 tha
46、t the long dimension is as nearly aspossible parallel to the direction of application of the load. Besure that 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 th
47、e jaws centrally in the widthwisedirection by having the line which was drawn 37 mm 1.5 in.from the edge of 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 slip
48、s in the jaws, breaks at the edge of orin the jaws, or if for any reason attributed to a faulty operationthe 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
49、 obtained.NOTE 2The decision to discard a break shall be based on observationof the specimen during the test 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
