1、Designation: D6768 04 (Reapproved 2009)Standard Test Method forTensile Strength of Geosynthetic Clay Liners1This standard is issued under the fixed designation D6768; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 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 The test method establishes the procedures for themeasurement of tensile strength of Geosynthetic Clay Liner(GCL). This te
3、st method is strictly an index test method to beused to verify the tensile strength of GCLs. Results from thistest method should not be considered as an indication of actualor long-term performance of the geosynthetic(s) in fieldapplications.1.2 The values in SI units are to be regarded as the stand
4、ard.Values in pound units are in parentheses for information.1.3 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 toest
5、ablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD2905 Practice for Statements on Number of
6、 Specimens forTextiles3D4439 Terminology for GeosyntheticsD5889 Practice for Quality Control of Geosynthetic ClayLinersD6072 Practice for Obtaining Samples of GeosyntheticClay Liners3. Terminology3.1 geosynthetic, na product manufactured wholly or inpart from polymeric material used with soil, rock,
7、 earth, orother geotechnical engineering related material as an integralpart of a project, structure, or system. D44393.2 geosynthetic clay liner, na manufactured hydraulicbarrier consisting of clay bonded to a layer or layers ofgeosynthetic material(s).3.3 For terminology of other terms used in thi
8、s test method,refer to Terminologies D123 and D4439.4. Summary of Test Method4.1 A100 mm (4-in). wide specimen is gripped across itsentire width in the clamps of a constant rate of extension (CRE)type tensile testing machine operated at a prescribed rate ofextension, applying a longitudinal force to
9、 the specimen untilthe specimen ruptures.5. Significance and Use5.1 This test method may be used for the acceptance testingof commercial shipments of GCLs but caution is advised sinceinformation about between-laboratory precision is incomplete.Comparative tests as directed in 5.1.1 may be advisable.
10、5.1.1 In cases of a dispute arising from differences inreported test results when using this test method for acceptanceof shipments, the purchaser and the supplier should conductcomparative tests to determine if there is a statistical bias. Thetwo parties should take a group of test samples that are
11、 ashomogeneous as possible and which are from the lot ofmaterial in question.5.2 Some modification of clamping techniques may benecessary for a given GCL depending upon its structure.Specimen clamping may be modified as required at thediscretion of the individual laboratory providing a representa-ti
12、ve tensile strength is obtained. In any event, the proceduredescribed in Section 10 of this test method for obtaining tensilestrength must be maintained.5.3 This test method is applicable for testing GCLs asreceived. It is used with a constant rate of extension typetension apparatus.1This test metho
13、d is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.04 on Geosyn-thetic Clay Liners.Current edition approved Nov. 1, 2009. Published January 2010. Originallyapproved in 2002. Last previous edition approved in 2004 as D676804 DOI:10.1
14、520/D6768-04R09.2For 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 standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this
15、 historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 Tensile Testing Machine, a constant rate of extension(CRE) type of testing machine described in Specification D76shall
16、be used with a minimum precision measuring capabilityof 0.1 N/m (5.71 3 10-4lbf/in.).6.2 Clamps, the clamps shall be a minimum 25 by 100 mm(1 by 4 in.) and with appropriate clamping power to preventslipping or crushing (damage).6.3 Die or Template, 100 by 200 mm (61 mm) (4 by 8in.(60.04 in.).6.4 Mis
17、cellaneous, knives, razor, etc, as required.7. Sampling and Test Specimens7.1 Lot SampleFor the lot sample, take rolls of GCLs asdirected in an applicable material specification, PracticeD5889, or as agreed upon between the purchaser and thesupplier.7.2 Laboratory SampleFor the laboratory sample, sa
18、mpleshall be taken in accordance with Guide D6072. The samplereceived at the testing laboratory should be in satisfactorycondition and representative of the product manufactured ordelivered to a site, or both.7.3 Test SpecimensA minimum of five test specimensshall be taken in the machine direction f
19、rom each swatch in thelaboratory sample. Take specimens from the laboratory sample,with those for the measurement of the machine direction tensileproperties from different positions across the GCL width. Nospecimens shall be taken within 10 cm (4 in.) of the selvage oredge of the GCL.7.4 The size of
20、 the die or template for cutting specimens is100 by 200 mm (minimum) (4 by 8 in.).7.5 The loss of clay during the specimen cutting processshould have no bearing on the results of the test.8. Conditioning8.1 The test specimen shall be tested as received.9. Procedure9.1 Obtain SpecimensUsing the die,
21、or template andrazor, and other necessary apparatus, carefully cut from thelaboratory sample five (5) test specimens. The five specimensshould be randomly selected from locations on the sample, butshould be distributed across the sample. All specimens shouldbe cut parallel to the machine direction.9
22、.2 Machine Set-Up ConditionsAdjust the distance be-tween the clamps at the start of the test to 100 6 3mm(460.1 in.). Set the CRE at 300 mm/min (12 in./min).9.3 Insertion of Specimen in ClampsMount the specimencentrally in the clamps. The specimen must be visuallyobserved 25 mm (1 in.) extend past t
23、he clamp. The specimenlength in the machine direction must be parallel to the directionof application of force.9.4 Measurement of Tensile StrengthStart the tensile test-ing machine.9.4.1 Continue testing the specimen until complete ruptureand record the maximum tensile force of the GCL.9.4.2 Reading
24、s of force and time shall be taken at aminimum rate of 20 readings per second.9.4.3 If a specimen slips in the jaws, or if for any reasonattributable to faulty operation the results fall significantlybelow the average for the set of specimens, discard the resultsand test another specimen. Continue u
25、ntil the required numberof readings has been taken.10. Calculation10.1 Tensile StrengthCalculate the tensile strength as readdirectly from the test instrument expressed in N/m (lbf/in.) ofwidth, using the following equation:afn5af11af21 . 1af5!5a5afnWswhere:afn= average recorded peak tensile strengt
26、h for specimen,N (lbf),a = tensile strength of the GCL, N/m (lbf/in.), andWs= specified specimen width, m (in.).11. Report11.1 Report the following information on tensile strength ofGCLs.11.1.1 All specimen values and average peak tensilestrength/unit width to the nearest 0.1 N/m (lbf/in.).11.1.2 If
27、 requested, the standard deviation, coefficient ofvariation, or both.11.1.3 Sample identification (for example, sample no., rollno., or other traceable identifier).11.1.4 Type of GCL tested.11.1.5 Type of testing machine and upper limit of load.11.1.6 Full scale force range used for testing.11.1.7 A
28、 statement of any departure from the suggestedtesting procedures so that the results can be evaluated and used.11.1.8 Note any cause or need for testing additional speci-mens due to rupture of the geotextile(s) during test, damage tospecimen from the grips, etc.11.2 Identification of testing agency,
29、 person performing thetest, date of test and client or project identification.11.3 Verification that the rupture of the GCL occurred.12. Precision and Bias12.1 Interlaboratory Test ProgramAn interlaboratorystudy of the test method was run in 2002/2003. Four differentgeosynthetic clay liner samples w
30、ere distributed to ten labora-tories. Three sets of test results were generated for each sampleby each of the laboratories.12.2 Test ResultsThe precision information is given inTable 1. The results are presented for the average of thecoefficient of variation, CV%, for the four samples.TABLE 1 Test R
31、esultsStatistic ILS AverageWithin laboratory repeatability limit, CVSr, % 4Between laboratory reproducibility limit, CVSR, % 895% confidence limit within laboratory repeatibility, CVr, % 1095% confidence limit between laboratory repeatibility, CVr, % 23D6768 04 (2009)212.3 BiasThe procedure in Test
32、Method D6768 for mea-suring the tensile strength of the geosynthetic clay liner has nobias because the value of the tensile strength of a geosyntheticclay liner is defined only in the terms of this test method.13. Keywords13.1 clay; geosynthetic; geosynthetic clay liner; tensilestrengthASTM Internat
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36、ds, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D6768 04 (2009)3
