1、Designation: D 4533 04Standard Test Method forTrapezoid Tearing Strength of Geotextiles1This standard is issued under the fixed designation D 4533; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method is an index test used to measure theforce
3、required to continue or propagate a tear in woven ornon-woven geotextiles by the trapezoid method. While usefulfor quality control and acceptance testing, the trapezoid teartest does not provide all the information needed for all designapplications and other test methods should be used.1.2 This test
4、 method is applicable to most geotextiles thatinclude woven fabrics, nonwoven fabrics, layered fabrics, knitfabrics, and felts that are used for geotextile applications.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address all of thesafety
5、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 Documents2.1 ASTM Standards:2D76 Specification for Tensile Testi
6、ng Machines for TextilesD 123 Terminology Relating to TextilesD 1776 Practice for Conditioning Textiles for TestingD 2905 Practice for Statements on Number of Specimensfor TextilesD 4354 Practice for Sampling of Geosynthetics for TestingD 4439 Terminology for Relating to Geosynthetics3. Terminology3
7、.1 Definitions:3.1.1 atmosphere for testing geotextiles, nair maintainedat a relative humidity of 65 6 5 % and a temperature of 21 62C (70 6 4F).3.1.2 geotextile, nany permeable textile material usedwith foundation, soil, rock, earth, or any other geotechnicalengineering related material as an integ
8、ral part of a man-madeproduct, structure, or system.3.1.3 tearing strength, nthe force required to either (1)start, or (2) continue or propagate a tear in a fabric underspecified conditions.3.1.3.1 DiscussionThis test method uses the maximumvalue of the tearing force as the tearing strength.3.1.4 Fo
9、r definitions of other terms used in this test method,refer to Terminology D 123 or Terminology D 4439.4. Summary of Test Method4.1 An outline of an isosceles trapezoid is marked on arectangular specimen cut for the determination of tearingstrength (see Fig. 1), and the nonparallel sides of the trap
10、ezoidmarked on the specimen are clamped in parallel jaws of atensile testing machine. The separation of the jaws is continu-ously increased so the tear propagates across the specimen. Atthe same time, the force developed is recorded. The tearingstrength, which is the maximum value of the tearing for
11、ce, isobtained from the autographic force extension curve (see Fig.2).5. Significance and Use5.1 The trapezoid tear method is a test that produces tensionalong a reasonably defined course such that the tear propagatesacross the width of the specimen. The trapezoid tearingstrength for woven fabrics i
12、s determined primarily by theproperties of the yarns that are gripped in the clamps. Innonwoven fabrics, because the individual fibers are more orless randomly oriented and capable of some reorientation in thedirection of the applied load, the maximum trapezoid tearingstrength is reached when the re
13、sistance to further reorientationis greater than the force required to rupture one or more fiberssimultaneously.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.10.0 on .Current edition approved Nov. 1, 2004. Publi
14、shed December 2004. Originallyapproved in 1991. Last previous edition approved in 1996 as D 453391(1996).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 standar
15、ds Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 The trapezoid tearing strength method is useful forestimating the relative tear resistance of different fabrics ordifferent directions in
16、 the same fabric.5.3 This test method may be used for acceptance testing ofcommercial shipments; however, caution is advised sinceinformation about between-laboratory precision is incomplete.Comparative tests as directed in 5.3.1 may be advisable.5.3.1 In case of a dispute arising from differences i
17、nreported test results when using this test method for acceptancetesting of commercial shipments, the purchaser and the sup-plier should conduct comparative tests to determine if there isa statistical bias between their laboratories. Competent statis-tical assistance is recommended for the investiga
18、tion of bias.As a minimum, the two parties should take a group of testspecimens that are as homogeneous as possible and that arefrom a lot of material of the type in question. Test specimensshould then be randomly assigned in equal numbers to eachlaboratory for testing. The average results from the
19、twolaboratories should be compared using the appropriate Stu-dents t-test and an acceptable probability level chosen by thetwo parties before testing is begun. If a bias is found, either itscause must be found and corrected or the purchaser and thesupplier must agree to interpret future test results
20、 in the light ofthe known bias.5.4 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
21、 them from slipping in theclamps or being damaged as a result of being gripped in theclamps.5.5 This test method may be used with constant-rate-of-traverse (CRT) or constant-rate-of-extension (CRE) type ten-sion machines. However, there may be no overall correlationbetween the results obtained with
22、the CRT machine and theCRE machine. Consequently, these two tension testers cannotbe used interchangeably. In case of controversy, the CREmachine shall prevail.6. Apparatus6.1 Tensile Testing Machine, of the constant-rate-of-extension (CRE) or constant-rate-of-traverse (CRT) type withautographic rec
23、order conforming to the requirements of Speci-fication D76.6.2 Clamps, having all gripping surfaces parallel, flat, andcapable of preventing slipping of the specimen during a test,and measuring 50.8 by no less than 76.2 mm (2 by no less than3 in.), with the longer dimension perpendicular to the dire
24、ctionof application of the load.6.3 Trapezoidal Template, optional, having the dimensionsshown in Fig. 1.7. Sampling and Selection7.1 Lot SampleAs a lot sample for acceptance testing,take at random the number of rolls of fabric directed in anapplicable material specification or other agreement betwe
25、enthe purchaser and the supplier, such as agreement to sample asdirected in Practice D 4354. Consider rolls of fabric to be theprimary sampling units.NOTE 1An adequate specification or other agreement between thepurchaser and the supplier requires taking into account the variabilitybetween rolls of
26、fabric and between specimens from a swatch from a rollof fabric so as to provide a sampling plan with a meaningful producersrisk, consumers risk, acceptable quality level, and limiting quality level.7.2 Laboratory SampleTake for the laboratory sample asample extending the width of the fabric and app
27、roximately 1m (39.37 in.) along the selvage from each roll in the lot sample.The sample may be taken from the end portion of a roll,provided there is no evidence that it is distorted or differentfrom other portions of the roll. In cases of dispute, take asample that will exclude fabric from the oute
28、r wrap of the rollor the inner wrap around the core.7.3 Test SpecimensTake test specimens as follows:FIG. 1 Trapezoidal Template for Trapezoid Tearing Strength TestFIG. 2 Typical Tearing Force Extension Curves for IndividualTest SpecimensD45330427.3.1 Woven FabricsTake the specimens to be used forth
29、e measurement of the tearing strength of machine directionyarns from different sets of machine direction yarns. Take thespecimens to be used for the measurement of the tearingstrength of cross-machine direction yarns from different sets ofcross-machine direction yarns and, when possible, from fabric
30、woven from different bobbins.7.3.2 Nonwoven FabricsTake the specimens for the mea-surement of the machine direction tearing strength fromdifferent positions across the fabric. Take the specimens for themeasurement of the cross-machine direction tearing strengthfrom different positions along the leng
31、th of the fabric.7.3.3 Cutting Test SpecimensTake no specimens nearerthe selvage or edge of the fabric than 1/20th of the fabric widthor, 150 mm (6 in.) whichever is smaller. Cut rectangularspecimens 76.2 by 201.6 mm (3 by 8 in.). Cut the specimens tobe used for the measurement of the tearing streng
32、th in themachine direction (or warp yarns), with the longer dimensionparallel to the machine direction (or warp yarns). Cut thespecimens to be used for the measurement of the tearingstrength in the cross-machine direction (or filling yarns) withthe longer dimension parallel to the cross-machine dire
33、ction (orfilling yarns). Mark each specimen with an isosceles trapezoidtemplate (see Fig. 1). Make a preliminary cut 15.9 mm (0.625in.) long at the center of the 25.4 mm (1 in.) edge, as shownFig. 1.7.3.4 Number of SpecimensUnless otherwise agreedupon, as when provided in an applicable material spec
34、ification,take a number of test specimens per swatch in the laboratorysample such that the user may expect at the 95 % probabilitylevel that the test result is not more than 5.0 % of the averageabove the true average of the swatch when testing in themachine and cross-machine directions, respectively
35、. Determinethe number of specimens per swatch as follows:7.3.4.1 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 for themachine and c
36、ross-machine directions 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 observations on similar materials in theusers laboratory under conditions of single-operatorprecision, %,t = the val
37、ue of Students t for one-sided limits (see Table1), a 95 % probability level, and the degrees offreedom associated with the estimate of v, andA = 5.0 % of the average, the value of the allowablevariation.7.3.4.2 No Reliable Estimate of vWhen there is no reli-able estimate of v for the users laborato
38、ry, Eq 1 should not beused directly. Instead, specify the fixed number (10) ofspecimens for the machine direction tests, and 10 specimensfor the cross-machine direction tests. The number of specimensis calculated using v = 9.5 % of the average for both machinedirection and cross-machine direction te
39、sts. These values for vare somewhat larger than usually found in practice. When areliable estimate of v for the users laboratory becomesavailable, Eq 1 will usually require fewer than the fixednumber of specimens. Table 18. Conditioning8.1 Bring the specimens to moisture equilibrium in theatmosphere
40、 for testing geotextiles (3.1). Equilibrium is consid-ered to have been reached when the increase in mass of thespecimen, in successive weighings made at intervals of not lessthan 2 h, does not exceed 0.1 % of the mass of the specimen.In general practice, the industry approaches equilibrium fromthe
41、“as received” side.NOTE 2It is recognized that in practice, geotextile materials arefrequently not weighed to determine when moisture equilibrium has beenreached. While such a method cannot be accepted in cases of dispute, itmay be sufficient in routine testing to expose the material to the standard
42、atmosphere 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 rates from the “as received” wet side. When this is known, apreconditioning cycle, as
43、 described in Practice D 1776, may be agreedupon by the contractural parties for routine testing.8.2 Specimens to be tested in the wet condition shall beimmersed in water maintained at a temperature of 21 6 2C(706 4F). The time of immersion must be sufficient to wet-outthe specimens thoroughly; this
44、 is indicated by no significantchange in strength or elongation following a longer period ofimmersion, and at least 2 min. To obtain thorough wetting, itmay be necessary, and advisable, to add not more than 0.05 %of a nonionic neutral wetting agent to the water.9. Procedure9.1 Test the conditioned s
45、pecimens in the standard atmo-sphere for testing as defined in 3.1.9.2 Test the thoroughly wet specimen in the normal machineset-up within 2 min. after removal from the water.9.3 Set the distance between the clamps at the start of thetest at 256 1mm(16 0.05 in.). The upper clamp should besupported b
46、y a free swivel or universal joint which will allowTABLE 1 Values of Students t for One-Sided Limits and the95 % ProbabilityAdfOne-SideddfOne-SideddfOne-Sided1 6.314 11 1.796 22 1.7172 2.920 12 1.782 24 1.7113 2.353 13 1.771 26 1.7064 2.132 14 1.761 28 1.7015 2.015 15 1.753 30 1.6976 1.943 16 1.746
47、40 1.6847 1.895 17 1.740 50 1.6768 1.860 18 1.734 60 1.6719 1.833 19 1.729 120 1.65810 1.812 20 1.725 1.645AValues in this table were calculated using Hewlett Packard HP 67/97 UsersLibrary Programs 03848D, “One-Sided and Two-Sided Critical Values of Studentst” and 00350D,“ Improved Normal and Invers
48、e Distribution”. For values at otherthan the 95 % probability level, see published tables of critical values of Studentst in any standard statistical text. Further use of this table is defined in PracticeD 2905.D4533043the clamp to rotate in the plane of the fabric. Select the loadrange of the testi
49、ng machine such that the maximum loadoccurs between 15 and 85 % of full-scale load. Set the machineto operate at a speed of 300 6 10 mm/min (12 6 0.5 in./min).9.4 Secure the test specimen in the machine, clamping alongthe nonparallel sides of the trapezoid so that the end edges ofthe clamps are in line with the 25-mm (1-in.) long side of thetrapezoid, and the cut is halfway between the clamps. Hold theshort edge taut and let the remaining fabric lie in folds.9.5 Start the machine and record the tearing force on theautographic recorder. The tearing f
