ASTM D6693/D6693M-20

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it 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 version
of the standard as published by ASTM is to be considered the official document.
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Designation: D6693/D6693M − 04 (Reapproved 2015) D6693/D6693M − 20
Standard Test Method for
Determining Tensile Properties of Nonreinforced
Polyethylene and Nonreinforced Flexible Polypropylene
Geomembranes
This standard is issued under the fixed designation D6693/D6693M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Designation was changed to dual and units information was corrected editorially in June 2015.
1. Scope
1.1 This test method covers the determination of the tensile properties of nonreinforced geomembranes in the form of standard
dumbbell-shaped test specimens when tested under defined conditions of pretreatment, temperature, and machine speed.
1.2 This test method can be used for testing materials thickness between 0.25 mm [0.010 in.] and 6.3 mm [0.25 in.].
NOTE 1—This test method is not intended to cover precise physical procedures. precisely measure physical properties of a geomembrane for design
purposes. This is an “index test” intended to be used for quality control and specification conformance purposes. The constant rate of crosshead movement
of this test lacks accuracy from a theoretical standpoint. standpoint, since crosshead movement as opposed to actual strain is used. A wide difference may
exist between the rate of crosshead movement and the rate of strain in particular areas of the specimen indicating that the testing speeds specified since
the specimen does not have a uniform width or cross-sectional area. This may disguise important effects or characteristics of these materials in the plastic
state. Use of an extensometer, not included in this test, would more accurately measure strain and strain rate but would still have limitations for some
geomembranes. Further, it is realized that variations in the thicknesses of test specimens, as permitted by this test method, produce variations in the
surface-volume ratios of such specimens, and that these variations may influence the test results. Hence, where directly comparable results are desired,
all samples should be of equal thickness. Special additional tests should be used where more precise physical data are needed. Test Method D4885 is a
suitable performance test for many applications.
1.3 Test data obtained by this test method are relevant and may be appropriate for use in engineering design with consideration
of test conditions as compared with in-service conditions.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D374/D374M Test Methods for Thickness of Solid Electrical Insulation
D412 Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension
D638 Test Method for Tensile Properties of Plastics
D4000 Classification System for Specifying Plastic Materials
D4439 Terminology for Geosynthetics
D4885 Test Method for Determining Performance Strength of Geomembranes by the Wide Strip Tensile Method
D5199 Test Method for Measuring the Nominal Thickness of Geosynthetics
This test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.
Current edition approved May 1, 2015July 1, 2020. Published June 2015July 2020. Originally approved in 2001. Last previous edition approved in 20102015 as
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D6693–04(2010).D6693/D6693M – 04 (2015) . DOI: 10.1520/D6693_D6693M-04R15E01.10.1520/D6693_D6693M-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6693/D6693M − 20
D5994/D5994M Test Method for Measuring Core Thickness of Textured Geomembranes
E4 Practices for Force Verification of Testing Machines
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2586 Practice for Calculating and Using Basic Statistics
3. Terminology
3.1 Definitions—Definitions of terms applying to this test method appear in Terminology D4439.
4. Significance and Use
4.1 This test method is designed to produce tensile property data for the control and specification of nonreinforced polyethylene
and flexible nonreinforced polypropylene geomembranes. These data are also useful for qualitative characterization and for
research and development. It may be necessary to modify this procedure for use in testing certain materials as recommended by
the material specifications. Therefore, it is advisable to refer to that material’s specification before using this test method. Table 1
in Classification D4000 lists the ASTM materials standards that currently exist.
4.2 Tensile properties may vary with specimen preparation, test speed, and environment of testing. Consequently, where precise
comparative results are desired, these factors must be carefully monitored and controlled.
4.2.1 It is realized that a material cannot be tested without also testing the method of preparation of that material. Hence, when
comparative tests of materials are desired, the care must be exercised to ensure that all samples are prepared in exactly the same
way, unless the test is to include the effects of sample preparation. Similarly, for referee purposes or comparisons within any given
series of specimens, care must be taken to secure the maximum degree of uniformity in details of preparation, treatment, and
handling.
NOTE 2—Tensile properties may provide useful data for plastics engineering design purposes. However, because of the high degree of sensitivity
exhibited by many plastics to rate of straining and environmental conditions, data obtained by this test method cannot be considered valid for applications
involving load-time scales or environments widely different from those of this test method. In cases of such dissimilarity, no reliable estimation of the
limit of usefulness can be made for most plastics. This sensitivity to rate of straining and environment necessitates testing over a broad load-time scale
and range of environmental conditions if tensile properties are to suffice for engineering design purposes.
5. Apparatus
5.1 Testing Machine—A testing machine of the constant-rate-of-crosshead-movement type and comprising essentially the
following:
5.1.1 Fixed Member—A fixed or essentially stationary member carrying one grip.
5.1.2 Movable Member—A movable member carrying a second grip.
5.1.3 Grips—Grips for holding the test specimen between the fixed member and the movable member of the test apparatus can
be either a fixed or self-aligning type.
5.1.3.1 Fixed grips are rigidly attached to the fixed and movable members of the test apparatus. Extreme care should be taken
when this type of grip is used to ensure that the test specimen is inserted and clamped so that the long axis of the test specimen
coincides with the direction of pull through the centerline of the grip assembly.
5.1.3.2 Self-aligning grips are attached to the fixed and movable members of the test apparatus. This type of grip assembly is
such that they will move freely into alignment as soon as any load is applied as long as the long axis of the test specimen will
coincide with the direction of the applied pull through the centerline of the grip assembly. The specimens should be aligned as
perfectly as possible with the direction of pull so that no rotary motion will occur in the grips thereby inducing slippage; there is
a limit to the amount of misalignment self-aligning grips will accommodate.
5.1.3.3 The test specimen shall be held in such a way that slippage relative to the grips is prevented as much as possible. Grip
surfaces that are deeply scored or serrated with a pattern similar to those of a coarse single-cut file, serrations about 2.4 mm [0.09
in.] apart and about 1.6 mm [0.06 in.] deep, have been found satisfactory for most thermoplastics. Finer serrations have been found
to be more satisfactory for harder plastics, such as the thermosetting materials. The serrations should be kept clean and sharp.
Breaking in the grips may occur at times, even when deep serrations or abraded specimen surfaces are used; other techniques must
be used in these cases. Other techniques that have been found useful, particularly with smooth-faced grips, are abrading that portion
of the surface of the specimen that will be in the grips, and interposing thin pieces of abrasive cloth, abrasive paper, plastic, or
rubber-coated fabric, commonly called hospital sheeting, between the specimen and the grip surface. No. 80 double-sided abrasive
paper has been found effective in many cases. An open-mesh fabric, in which the threads are coated with abrasive, has also been
effective. Reducing the cross-sectional area of the specimen may also be effective. The use of special types of grips is sometimes
necessary to eliminate slippage and breakage in the grips.
5.1.4 Drive Mechanism—A drive mechanism for imparting to the movable member a uniform, controlled velocity with respect
to the stationary member, with this velocity to be regulated as specified in Section 9.
5.1.5 Load Indicator—A suitable load-indicating mechanism capable of showing the total tensile load carried by the test
specimen when held by the grips. This mechanism shall be essentially free of inertiainertial lag at the specified rate of testing and
shall indicate the load with an accuracy of 61 % of the indicated value, or better. The accuracy of the testing machine shall be
verified in accordance with Practices E4.
D6693/D6693M − 20
NOTE 2—Experience has shown that many testing machines now in use are incapable of maintaining accuracy for as long as the periods between
inspection recommended in Practices E4. Hence, it is recommended that each machine be studied individually and verified as often as may be found
necessary. It frequently will be necessary to perform this function daily.
5.1.6 Crosshead Extension Indicator—A suitable extension-indicating mechanism capable of showing the amount of change in
the separation of the grips, that is, crosshead movement, for the calculation of a strain value for yield and break using the specified
gauge length for each. This mechanism shall be essentially free of inertial lag at the specified rate of testing and shall indicate the
crosshead movement with an accuracy of 610 % of the indicated value.
6. Samples and Test Specimens
6.1 A sample can come from sheet, plate, or molded plastics and can be isotropic or anisotropic.
6.2 Record any necessary identification for each sample and maintain that identification with the prepared specimens.
6.3 Sheet, Plate, and Molded Plastics: Test Specimen Dimensions:
6.3.1 The test specimens shall conform to the dimensions shown in Fig. 1. This specimen geometry was adopted from Test
Method D638 and is therefore equivalent to Type IV of said standard.
6.3.2 Test specimens shall be prepared by die cutting from materials in sheet, plate, slab, or similar form.
Specimen Dimensions for Type IV Dog Bone of Thickness, T, mm [in.]
Description Dimension, mm [in.] Tolerances, mm [in.]
W–width of narrow section 6 [0.25] ±0.5 [±0.02]
L–length of narrow section 33 [1.30] ±0.5 [±0.02]
GL –gauge length for yield 33 [1.30] ±0.5 [±0.02]
Y
GL –gauge length for break 50 [2.0] ±0.5 [±0.02]
B
WO–width overall 19 [0.75] ±6.4 [±0.25]
LO–length overall 115 [4.5] No max, No min
G–gauge length 25 [1.00] ±0.5 [±0.02]
D–distance between grips 65 [2.5] ±0.13 [±0.005]
R–radius of fillet 14 [0.56] ±1 [±0.04]
RO–outer radius 25 [1.00] ±1 [±0.04]
Specimen Dimensions for Type IV Dog Bone of Thickness, T, mm [in.]
Description Dimension, mm [in.] Tolerances, mm [in.]
A
W—width of narrow section 6 [0.25] ±0.5 [±0.02]
L—length of narrow section 33 [1.30] ±0.5 [±0.02]
GL —gauge length for yield 33 [1.30] . . .
Y
GL —gauge length for break 50 [2.0] . . .
B
WO—width overall 19 [0.75] ±6.4 [±0.25]
LO—length overall 115 [4.5] No max, No min
D—distance between grips 65 [2.5] ±0.13 [±0.005]
R—radius of fillet 14 [0.56] ±1 [±0.04]
RO—outer radius 25 [1.00] ±1 [±0.04]
A
For the Type IV specimen, the internal width of the narrow section of the die shall be 6.00 ± 0.05 mm [0.250 ± 0.002 in.]. The dimensions are essentially those of Die
C in Test Methods D412.
FIG. 1 Type IV Dog Bone Specimen
D6693/D6693M − 20
6.4 All surfaces of the specimen shall be free of visible flaws, scratches, or imperfections. If the specimen exhibits such
markings, it should be discarded and replaced. If these flaws or imperfections are present in the new specimen, the die should be
inspected for flaws.
NOTE 3—Negative effects from imperfections on the edge of the specimens can severely impact the results of this test and should therefore be carefully
monitored. In cases of dispute over the results, inspection of the die and specimen prep
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