1、Designation: D6818 17D6818 18Standard 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
2、of last 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 determining the tensile properties of rolled erosion control prod
3、ucts(RECPs).1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for informationpurposes only.1.3 This standard does not apply to RECPs made of composite materials where the component providing the reinforcementcannot be tested for tensil
4、e strength with the procedure herein described. In this case, the establishedASTM testing method whichis most appropriate for that material shall be used instead.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the
5、user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestab
6、lished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D76/D76M Specification for Tensile Testing Machines for Textile
7、sD4354 Practice for Sampling of Geosynthetics and Rolled Erosion Control Products (RECPs) for TestingE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Terminology3.1 Definition
8、s:3.1.1 breaking load, nthe maximum force applied to a specimen in a tensile test carried to rupture.3.1.1.1 DiscussionMaterials that are brittle usually rupture at the maximum force. Materials that are ductile usually experience a maximum forcebefore rupturing.3.1.2 constant rate of extension (CRE)
9、 tensile testing machinea testing machine in which the rate of increase of specimenlength is uniform with time.3.1.3 elongation, nthe ratio of the extension of a material to the length of the material prior to stretching. (Compare extension.)3.1.4 extension, nthe change in length of a material due t
10、o stretching. (Compare elongation.)3.1.5 rupture, vthe act of bursting.1 This test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.05 on Geosynthetic ErosionControl.Current edition approved Jan. 1, 2017Feb. 1, 2018. Publish
11、ed January 2017February 2018. Originally approved in 2002. Last previous edition approved in 20142017 asD6818 14.17. DOI: 10.1520/D6818-17.10.1520/D6818-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM
12、 Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically pos
13、sible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, W
14、est Conshohocken, PA 19428-2959. United States13.1.6 strip test, nin RECP testing, a tensile test in which the full width of the specimen is gripped in the clamps.3.1.7 tensile test, nin geosynthetics, a test in which a geosynthetic material is stretched in one direction to determine theforce-elonga
15、tion characteristics, the breaking force, or the breaking elongation.4. Summary of Test Method4.1 A test specimen is clamped in a tensile testing machine and a force applied to the specimen until it breaks. Values for thebreaking force and elongation of the test specimen are obtained from machine sc
16、ales, dials, autographic recording charts, or acomputer 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 satisfactory for acceptance testing of commercial shipments of rolled er
17、osioncontrol products since the method has been used extensively in the trade for acceptance testing.5.1.1 In case of disagreement arising from differences in reported test values when using this test method for acceptance testingof commercial shipments, the purchaser and the supplier should conduct
18、 comparative tests to determine if there is statistical biasbetween their laboratories. Competent statistical assistance is recommended for the investigation of bias.AsAt a minimum, the twoparties should take a group of test specimens which are as homogeneous as possible and are from a lot of materi
19、al of the type inquestion. The test specimens should then be randomly assigned in equal numbers to each laboratory for testing. The average resultsfrom the two laboratories should be compared using Students t-test for unpaired data and an acceptable probability level chosenby the two parties before
20、testing is begun. If bias is found, either its cause must be found and corrected, or the purchaser and thesupplier must agree to interpret future results in the light of the known bias.6. Apparatus6.1 Tensile Testing Machine, of the constant rate of extension (CRE) type conforming to Specification D
21、76/D76M, with respectto force indication, working range, capacity, and elongation indicator and designed for operation at a speed of 300 6 10 mm/min(12 6 0.5 in./min).6.2 Clamps and Jaw FacesEach jaw face shall be smooth, flat, and with a metallic or other agreed-upon surface. The facesshall be para
22、llel and have machining centers with respect to one another in the same clamp and to the corresponding jaw face ofthe other clamp. The jaw faces shall measure at least 10 mm (0.5 in.) wider than the specimen being tested and at least 25 mm(1.0 in.) in height.7. Sampling7.1 Lot SampleIn the absence o
23、f other guidelines, divide the product into lots and take lot samples in accordance with PracticeD4354.7.2 Laboratory SampleFor the laboratory sample, take a full-width sample of sufficient length in the machine direction so thatthe required size and number of specimens can be obtained. Exclude the
24、inner and outer layers or wraps of the roll or any materialcontaining folds, crushed areas, or other distortions not representative of the sampled lot.7.3 Remove test specimens from the laboratory sample so that each specimen will contain different machine and cross-machineelements with no specimen
25、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 either to the machine direction or to the cross-machine direction, or cutspecimens for testing both directions as required. Unless otherwise specified, take s
26、pecimens no nearer to the machine directionedge of the RECP than one-tenth of the width of the RECP. Cut each specimen 100 mm (4 in.) wide, by at least 150 mm (6 in.)long.NOTE 1The length of the specimen depends on the type of clamps being used. The specimen should be long enough to extend through t
27、he clampsand project at least 12.5 mm (0.5 in.) at each end and provide a gage length of 75 mm (3.0 in.).7.5 Number of SpecimensUnless otherwise agreed upon, as when provided in an applicable material specification, take thenumber of test specimens per laboratory sample as follows:7.5.1 Reliable Est
28、imate of vWhen there is a reliable estimate of v based upon extensive part records for similar materialstested in the users laboratory as directed in this test method, calculate the required number of specimens as follows so that theuser may expect at the 95 % probability level that the test result
29、is not more than 5.0 % of the average above or below the averageof the sample:n 5t v A!2 (1)where:n = number of test specimens (rounded upward to a whole number),v = coefficient of variation of individual observations on similar materials in the users laboratory under conditions of singleoperation p
30、recision, %,D6818 182v = coefficient of variation of individual observations on similar materials in the users laboratory under conditions ofsingle-operator precision, %,t = value of Students t for one-sided limits, a 95 % probability level, and the degrees of freedom associated with the estimateof
31、v (see Table 1), andA = 5.0 % of the average, the value of the allowable variation.7.5.2 No Reliable Estimate of vWhen there is no reliable estimate of v for the users laboratory, measurements shall be madeon a minimum of five (5) specimens per laboratory sample.8. Conditioning8.1 Bring the specimen
32、s to the moisture and temperature equilibrium in the atmosphere for testing rolled erosion controlproducts, that is, a temperature of 21 6 2 C (70 6 4 F) and a 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 testing machine.
33、 Take care that the specimen is centrally located and thatthe long dimension is as nearly parallel as possible to the direction of force application. Be sure that the tension on the specimenis uniform across the clamped width. Clamps which are too tight will produce breaks at the clamp line; clamps
34、which are too loosewill cause slippage.9.3 Operate the machine and break the specimen. The rate of extension of the gage length should be 300 6 10 mm/min (12 60.5 in./min).9.4 Read the breaking force and elongation, from the mechanism provided for such purpose. Record machine and cross-machinedirect
35、ion results separately. If desired, additional points along the stress/strainstress-strain curve can be recorded as well.9.5 For some machines, data may be obtained using an interfaced computer.9.6 If a specimen slips in the jaws, or breaks at the edge of or in the jaws, or if for any reason the res
36、ult falls markedly belowthe average of the set of specimens, discard the result and take another specimen. Continue this until the required numbers ofbreaks have been obtained.NOTE 2It is difficult to determine the precise reason that certain specimens break near the edge of the jaws. If such a brea
37、k is by damage to thespecimen by the jaws, then the results should be discarded. If, however, the break is merely due to randomly distributed weak places, it is a legitimateresult. In some cases, it may also be caused by a concentration of stress in the area adjacent to the jaws because the jaws pre
38、vent the specimen fromcontracting in the width as the force is applied. In such cases, a break near the edge of the jaw is inevitable and should be accepted as a characteristicof the particular method of test.10. Calculation10.1 Breaking Force perPer Unit Width For each laboratory sample, calculate
39、the average of the breaking force observed forall acceptable specimens, that is, the maximum force exerted on the specimen as read directly from the testing machine indicatingmechanism and divide this force by the width of the strip. The resulting value is expressed in kilonewtons/meter.10.2 Elongat
40、ionFor each laboratory sample, calculate the average of the elongation observed for all acceptable specimens,that is, the elongation that corresponds to the maximum force as stated above, as read directly from the testing machine indicatingmechanism. The elongation is expressed as a percentage.11. R
41、eport11.1 State that the specimens were tested as directed in Test Method D6818. Describe the material or product sampled and themethod of sampling used.TABLE 1 Values of Students t for One-Sided Limits and the 95 %Probabilitydf One-Sided df One-Sided df One-Sided1 6.314 11 1.796 22 1.7172 2.920 12
42、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 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 18311.2 Report the following for each laboratory sample:11.2.1 The average breaki
43、ng force per unit width of acceptable specimens for each test.11.2.2 The average elongation at break of acceptable specimens 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 based
44、on an interlaboratory study of Test Method D6818 Standard TestMethod for Ultimate Tensile Properties of Turf Reinforcement Mats, conducted in 2013. Four laboratories participated in this,conducted in 2013 and 2014. Four laboratories participated in the 2013 study and three laboratories participated
45、in the 2014 study.Each of the labs reported three replicate test results for two different types of mats and a double net blanket. each of the testedRECPs. Every “test result” reported represents the average of five measurements taken from a sample. Except for the ultimate useof data from only four
46、fewer than six laboratories, Practice E691 was followed for the design and analysis of the data; the detailsare given in ASTM Research Report No.Nos. RR:D35-10163RR:D35-1016. and RR:D35-1026.412.1.1 Repeatability (r)(r)The difference between repetitive results obtained by the same operator in a give
47、n laboratoryapplying the same test method with the same apparatus under constant operating conditions on identical test material within shortintervals of time would, in the long run, in the normal and correct operation of the test method, exceed the following values onlyin one case in 20.12.1.1.1 Re
48、peatability can be interpreted as the maximum difference between two results, obtained under repeatabilityconditions, that is accepted as plausible due to random causes under normal and correct operation of the test method.12.1.1.2 Repeatability limits are listed in Tables 2-5.12.1.2 Reproducibility
49、 (R)(R)The difference between two single and independent results obtained by different operatorsapplying the same test method in different laboratories using different apparatus on identical test material would, in the long run,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 maximum difference between two results, obtained under reproducibilityconditions, that is accepted as plausible due to random causes under normal and correct opera
