1、Designation: D6818 18aStandard Test Method forUltimate Tensile Properties of Rolled Erosion ControlProducts1This standard is issued under the fixed designation D6818; 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 This test method covers strip test procedures for deter-mining the tensile properties of rolled erosion control products(R
3、ECPs).1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are provided forinformation purposes only.1.3 This standard does not apply to RECPs made of com-posite materials where the component providing the reinforce-ment cannot be tested for tensile st
4、rength with the procedureherein described. In this case, the established ASTM testingmethod which is most appropriate for that material shall beused instead.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 o
5、f this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the
6、 Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D76/D76M Specification for Tensile Testing Machines forTextilesD4354 Practic
7、e for Sampling of Geosynthetics and RolledErosion Control Products (RECPs) for TestingE177 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:3.1.1 breaking
8、load, nthe maximum force applied to aspecimen in a tensile test carried to rupture.3.1.1.1 DiscussionMaterials that are brittle usually rup-ture at the maximum force. Materials that are ductile usuallyexperience a maximum force before rupturing.3.1.2 constant rate of extension (CRE) tensile testingm
9、achinea testing machine in which the rate of increase ofspecimen length is uniform with time.3.1.3 elongation, nthe ratio of the extension of a materialto the length of the material prior to stretching. (Compareextension.)3.1.4 extension, nthe change in length of a material due tostretching. (Compar
10、e elongation.)3.1.5 rupture, vthe act of bursting.3.1.6 strip test, nin RECP testing, a tensile test in whichthe full width of the specimen is gripped in the clamps.3.1.7 tensile test, nin geosynthetics, a test in which ageosynthetic material is stretched in one direction to determinethe force-elong
11、ation characteristics, the breaking force, or thebreaking elongation.4. Summary of Test Method4.1 A test specimen is clamped in a tensile testing machineand a force applied to the specimen until it breaks. Values forthe breaking force and elongation of the test specimen areobtained from machine scal
12、es, dials, autographic recordingcharts, or a computer interfaced with the testing machine.Also,points along the stress-strain curve can be reported.5. Significance and Use5.1 The strip test in this test method is considered satisfac-tory for acceptance testing of commercial shipments of rollederosio
13、n control products, since the method has been usedextensively in the trade for acceptance testing.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.05 on Geosyn-thetic Erosion Control.Current edition approved June 1
14、, 2018. Published June 2018. Originallyapproved in 2002. Last previous edition approved in 2018 as D6818 18. DOI:10.1520/D6818-18A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa
15、tion, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization
16、 established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15.1.1 In case of disagreement arising from differences inreported test values when using this test
17、method for acceptancetesting of commercial shipments, the purchaser and the sup-plier should conduct comparative tests to determine if there isstatistical bias between their laboratories. Competent statisticalassistance is recommended for the investigation of bias. At aminimum, the two parties shoul
18、d take a group of test speci-mens which are as homogeneous as possible and are from a lotof material of the type in question. The test specimens shouldthen be randomly assigned in equal numbers to each laboratoryfor testing. The average results from the two laboratoriesshould be compared using Stude
19、nts t-test for unpaired dataand an acceptable probability level chosen by the two partiesbefore testing is begun. If bias is found, either its cause must befound and corrected, or the purchaser and the supplier mustagree to interpret future results in the light of the known bias.6. Apparatus6.1 Tens
20、ile Testing Machine, of the constant rate of exten-sion (CRE) type conforming to Specification D76/D76M, withrespect to force indication, working range, capacity, andelongation indicator and designed for operation at a speed of300 6 10 mm/min (12 6 0.5 in./min).6.2 Clamps and Jaw FacesEach jaw face
21、shall be smooth,flat, and with a metallic or other agreed-upon surface. Thefaces shall be parallel and have machining centers with respectto one another in the same clamp and to the corresponding jawface of the other clamp. The jaw faces shall measure at least10 mm (0.5 in.) wider than the specimen
22、being tested and atleast 25 mm (1.0 in.) in height.7. Sampling7.1 Lot SampleIn the absence of other guidelines, dividethe product into lots and take lot samples in accordance withPractice D4354.7.2 Laboratory SampleFor the laboratory sample, take afull-width sample of sufficient length in the machin
23、e directionso that the required size and number of specimens can beobtained. Exclude the inner and outer layers or wraps of theroll or any material containing folds, crushed areas, or otherdistortions not representative of the sampled lot.7.3 Remove test specimens from the laboratory sample sothat e
24、ach specimen will contain different machine and cross-machine elements, with no specimen taken nearer than 100 mm(4 in.) from the roll sides or ends, unless otherwise specified.7.4 Cut specimens with their long dimension parallel eitherto the machine direction or to the cross-machine direction, orcu
25、t specimens for testing both directions as required. Unlessotherwise specified, take specimens no nearer to the machinedirection edge of the RECP than one-tenth of the width of theRECP. Cut each specimen 100 mm (4 in.) wide, by at least150 mm (6 in.) long.NOTE 1The length of the specimen depends on
26、the type of clampsbeing used.NOTE 2The specimens may be taped across the width on each side ofthe long dimension to maintain specimen integrity during specimenpreparation and positioning within the grips during setup and testing. Anytape with sufficient strength, adhesion, and durability to withstan
27、d grippressures and hold specimen components securely is acceptable. The tapeshould not extend into the test area (that is, between the grips, within the3-in. gage length). See Fig. 1.7.5 Number of SpecimensUnless otherwise agreed upon,as when provided in an applicable material specification, taketh
28、e number of test specimens per laboratory sample as follows:7.5.1 Reliable Estimate of vWhen there is a reliableestimate of v based upon extensive part records for similarmaterials tested in the users laboratory as directed in this testmethod, calculate the required number of specimens as followsso
29、that the user may expect at the 95 % probability level thatthe test result is not more than 5.0 % of the average above orbelow the average of the sample:FIG. 1 Taping of SpecimensD6818 18a2n 5 tv A!2(1)where:n = number of test specimens (rounded upward to a wholenumber),v = coefficient of variation
30、of individual observations onsimilar materials in the users laboratory under condi-tions of single-operator precision, %,t = value of Students t for one-sided limits, a 95 %probability level, and the degrees of freedom associatedwith the estimate of v (see Table 1), andA = 5.0 % of the average, the
31、value of the allowablevariation.7.5.2 No Reliable Estimate of vWhen there is no reliableestimate of v for the users laboratory, measurements shall bemade on a minimum of five (5) specimens per laboratorysample.8. Conditioning8.1 Bring the specimens to the moisture and temperatureequilibrium in the a
32、tmosphere for testing rolled erosion controlproducts, that is, a temperature of 21 6 2 C (70 6 4 F) anda relative humidity of 60 6 10 %.9. Procedure9.1 Set gage length to 75 mm.9.2 Mount the specimen securely in the clamp of the testingmachine. Take care that the specimen is centrally located andtha
33、t the long dimension is as nearly parallel as possible to thedirection of force application. The specimen should be longenough to extend through the clamps and project at least12.5 mm (0.5 in.) at each end and provide a gage length of75 mm (3.0 in.). Be sure that the tension on the specimen isunifor
34、m across the clamped width. Clamps that are too tightwill produce breaks at the clamp line; clamps that are too loosewill cause slippage.9.3 Operate the machine and break the specimen. The rateof extension of the gage length should be 300 6 10 mm/min(12 6 0.5 in./min).9.4 Read the breaking force and
35、 elongation, from themechanism provided for such purpose. Record machine andcross-machine direction results separately. If desired, addi-tional points along the stress-strain curve can be recorded aswell.9.5 For some machines, data may be obtained using aninterfaced computer.9.6 If a specimen slips
36、in the jaws, breaks at the edge of orin the jaws, or if for any reason the result falls markedly belowthe average of the set of specimens, discard the result and takeanother specimen. Continue this until the required number ofbreaks has been obtained.NOTE 3It is difficult to determine the precise re
37、ason that certainspecimens break near the edge of the jaws. If such a break is by damageto the specimen by the jaws, then the results should be discarded. If,however, the break is merely due to randomly distributed weak places, itis a legitimate result. In some cases, it may also be caused by aconce
38、ntration of stress in the area adjacent to the jaws because the jawsprevent the specimen from contracting in the width as the force is applied.In such cases, a break near the edge of the jaw is inevitable and should beaccepted as a characteristic of the particular method of test.10. Calculation10.1
39、Breaking Force per Unit WidthFor each laboratorysample, calculate the average of the breaking force observedfor all acceptable specimens, that is, the maximum forceexerted on the specimen as read directly from the testingmachine indicating mechanism, and divide this force by thewidth of the strip. T
40、he resulting value is expressed inkilonewtons/meter.10.2 ElongationFor each laboratory sample, calculate theaverage of the elongation observed for all acceptablespecimens, that is, the elongation that corresponds to themaximum force as stated above, as read directly from thetesting machine indicatin
41、g mechanism. The elongation isexpressed as a percentage.11. Report11.1 State that the specimens were tested as directed in TestMethod D6818. Describe the material or product sampled andthe method of sampling used.11.2 Report the following for each laboratory sample:11.2.1 The average breaking force
42、per unit width of accept-able specimens for each test.11.2.2 The average elongation at break of acceptable speci-mens for each test.11.2.3 Number of specimens tested in each direction.11.2.4 Size of jaw faces used.12. Precision and Bias12.1 PrecisionThe precision of this test method is basedon an in
43、terlaboratory study of Test Method D6818, conductedin 2013 and 2014. Four laboratories participated in the 2013study and three laboratories participated in the 2014 study.Each of the labs reported three replicate test results for each ofthe tested RECPs. Every “test result” reported represents theav
44、erage of five measurements taken from a sample. Except forthe use of data from fewer than six laboratories, Practice E691TABLE 1 Values of Students t for One-Sided Limits and the 95 %ProbabilitydfOne-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 1.7
45、064 2.132 14 1.761 28 1.7015 2.015 15 1.753 30 1.6976 1.943 16 1.746 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 1.645D6818 18a3was followed for the design and analysis of the data; the detailsare given in ASTM Research Report Nos. RR:D35-101
46、63andRR:D35-1026.412.1.1 Repeatability (r)The difference between repetitiveresults obtained by the same operator in a given laboratoryapplying the same test method with the same apparatus underconstant operating conditions on identical test material withinshort intervals of time would, in the long r
47、un, in the normal andcorrect operation of the test method, exceed the followingvalues only in one case in 20.12.1.1.1 Repeatability can be interpreted as the maximumdifference between two results, obtained under repeatabilityconditions, that is accepted as plausible due to random causesunder normal
48、and correct operation of the test method.12.1.1.2 Repeatability limits are listed in Tables 2-5.12.1.2 Reproducibility (R)The difference between twosingle and independent results obtained by different operatorsapplying the same test method in different laboratories usingdifferent apparatus on identi
49、cal test material would, in the longrun, in the normal and correct operation of the test method,exceed the following values only in one case in 20.12.1.2.1 Reproducibility can be interpreted as the maximumdifference between two results, obtained under reproducibilityconditions, that is accepted as plausible due to random causesunder normal and correct operation of the test method.12.1.2.2 Reproducibility limits are listed in Tables 2-5.12.1.3 The terms repeatability limit and reproducibilitylimit are used as specified in Practice E177.12.1.4 A
