1、Designation: D6818 14D6818 17Standard 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(RECP).rolled erosion control products (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 RECPsRECPs made of composite materials where the component providing
4、thereinforcement cannot be tested for tensile strength with the procedure herein described. In this case, the established ASTM testingmethod,method which is most appropriate for that material,material shall be used instead.1.4 This standard does not purport to address all of the safety concerns, if
5、any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D76/D76M Specification for Tensile Testing Machines
6、 for TextilesD4354 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
7、 Definitions: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 exte
8、nsion (CRE) 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 mat
9、erial due to stretching. (Compare elongation.)3.1.5 rupture, vthe act of bursting.3.1.6 strip test, nin RECP testing, a tensile test in which the full width of the specimen is gripped in the clamps.1 This test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct
10、responsibility of Subcommittee D35.05 on Geosynthetic ErosionControl.Current edition approved May 1, 2014Jan. 1, 2017. Published May 2014January 2017. Originally approved in 2002. Last previous edition approved in 20092014 as D6818 02 (2009). 14. DOI: 10.1520/D6818-14.10.1520/D6818-17.2 For referenc
11、edASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM 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 u
12、ser of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard
13、as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.7 tensile test, nin geosynthetics, a test in which a geosynthetic material is stretched in one direction to determine t
14、he force- elongation force-elongation 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 spec
15、imen are obtained from machine scales, 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
16、commercial shipments of Rolled ErosionControl Productsrolled erosion control 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 com
17、mercial shipments, the purchaser and the supplier should conduct comparative tests to determine if there is statistical biasbetween their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the twoparties should take a group of test specimenspec
18、imens which are as homogeneous as possible and are from a lot of material of thetype in question. The test specimenspecimens should then be randomly assigned in equal numbers to each laboratory for testing.The average results from the two laboratories should be compared using Students t-testt-test f
19、or unpaired data and an acceptableprobability level chosen by the two parties before testing is begun. If bias is found, either its cause must be found and corrected,or the purchaser and the supplier must agree to interpret future results in the light of the known bias.6. Apparatus6.1 Tensile Testin
20、g Machine, of the Constant Rateconstant rate of Extensionextension (CRE) type conforming to SpecificationD76/D76M, with respect to force indication, working range, capacity, and elongation indicator and designed for operation at aspeed of 300 6 10 mm/min (12 6 0.5 in./min).6.2 Clamps and Jaw FacesEa
21、ch jaw face shall be smooth, flat, and with a metallic or other agreed upon agreed-upon surface.The faces shall be parallel and have machining centers with respect to one another in the same clamp and to the correspondingjaw face of the other clamp. The jaw faces shall measure at least 10 mm 10 mm (
22、0.5 in.) wider than the specimen being testedand at least 25 mm (1.0 in.) in height.7. Sampling7.1 Lot SampleTake a lot sample as directed in the applicable materialIn the absence of other guidelines, divide the productinto lots and take lot samples in accordance with Practice D4354specifications7.2
23、 Laboratory SampleFrom each roll or piece of RECP taken from the lot sample, cut at least one laboratory sample the fullwidth of the RECP and 1 m (1 yd) along the edge in the machine direction.For the laboratory sample, take a full-width sampleof sufficient length in the machine direction so that th
24、e required size and number of specimens can be obtained. Exclude the innerand outer layers or wraps of the roll or any material containing folds, crushed areas, or other distortions not representative of thesampled lot.7.3 Test SpecimenFrom each laboratory sample, take five specimens from each direc
25、tion for each test.Remove test specimensfrom the laboratory sample so that each specimen will contain different machine and cross-machine elements with no specimentaken nearer than 100 mm (4 in.) from the roll sides or ends, unless otherwise specified.7.4 Cut specimens with their long dimension para
26、llel either to the machine direction or to the cross machine cross-machinedirection, or cut specimens for testing both directions as required. Unless otherwise specified, take specimens no nearer to themachine direction edge of the RECP than one tenth one-tenth of the width of the RECP. Cut each spe
27、cimen 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 the 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 Numb
28、er of SpecimensCut each specimen 100 mm (4 in.) wide, by at least 150 mm (6 in.) long.Unless otherwise agreedupon, as when provided in an applicable material specification, take the number of test specimens per laboratory sample as follows:7.5.1 Reliable Estimate of vWhen there is a reliable estimat
29、e 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 is not more than 5.0 % of the average abov
30、e or below the averageof the sample:n 5t v A!2 (1)where:n = number of test specimens (rounded upward to a whole number),D6818 172v = coefficient of variation of individual observations on similar materials in the users laboratory under conditions of singleoperation precision, %,t = value of Students
31、 t for one-sided limits, a 95 % probability level, and the degrees of freedom associated with the estimateof 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, measurement
32、s shall be madeon a minimum of five (5) specimens per laboratory sample.NOTE 1The length of the specimen depends on the type of clamps being used. The specimen should be long enough to extend through the clampsand project at least 12.5 mm (12 in.) at each end and provide a gage length of 75 mm.8. Co
33、nditioning8.1 Bring the specimens to the moisture and temperature equilibrium in the atmosphere for testing RECPs, that isrolled erosioncontrol products, that is, a temperature of 21 6 2C2 C (70 6 4F)4 F) and a relative humidity of 60 6 10 %.9. Procedure9.1 Set gage length to 75 mm.9.2 Mount the spe
34、cimen securely in the clamp of the testing machine. 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 t
35、ight will produce breaks at the clamp line; clamps 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 s
36、uch purpose. Record machine and cross machinecross-machine direction results separately. If desired, additional points along the stress/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
37、edge of or in the jaws, or if for any reason the resultsresult falls markedlybelow the average of the set of specimens, discard the result and take another specimen. Continue this until the required numbersof breaks have been obtained.NOTE 2It is difficult to determine the precise reason that certai
38、n specimens break near the edge of the jaws. If such a break 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 s
39、tress in the area adjacent to the jaws because the jaws prevent 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 For
40、ce per Unit Width For each laboratory sample, calculate the average of the breaking force observed for allacceptable 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 result
41、ing value is expressed in Kilo Newtons/Meter.kilonewtons/meter.10.2 ElongationFor 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 mac
42、hine indicatingmechanism. The elongation is expressed in percent.as a percentage.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 1.782 24 1.7113 2.353 13 1.771 26 1.7064 2.132 14 1.761 28 1.7015 2.015
43、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 17311. Report11.1 State that the specimens were tested as directed in Test Method D6818. Describe the material or product sampled and themethod of sampli
44、ng used.11.2 Report the following for each laboratory sample:11.2.1 The average breaking 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 face
45、s used.12. Precision and Bias312.1 PrecisionThe precision of this test method is based on an interlaboratory study of D6818 Standard Test Method forUltimate Tensile Properties of Turf Reinforcement Mats, conducted in 2013. Four laboratories participated in this study. Each ofthe labs reported three
46、replicate test results for two different types of mats and a double net blanket. Every “test result” reportedrepresents the average of five measurements taken from a sample. Except for the ultimate use of data from only four laboratories,Practice E691 was followed for the design and analysis of the
47、data; the details are given in ASTM Research Report No.RR:D35-1016.12.1.1 Repeatability (r)The difference between repetitive results obtained by the same operator in a given laboratory applyingthe same test method with the same apparatus under constant operating conditions on identical test material
48、 within short intervalsof time would in the long run, in the normal and correct operation of the test method, exceed the following values only in one casein 20.12.1.1.1 Repeatability can be interpreted as the maximum difference between two results, obtained under repeatabilityconditions, that is acc
49、epted 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 1-2-45.12.1.2 Reproducibility (R)The difference between two single and independent results obtained by different operators applyingthe same test method in different laboratories using different apparatus on identical test material would, in the long run, in thenormal and correct operation of the test method, exceed the following values only in one case in 20.12.1.2.1 Reproducibility can be interpre
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