ASTM D4885-01(2011)
(Test Method)Standard Test Method for Determining Performance Strength of Geomembranes by the Wide Strip Tensile Method
Standard Test Method for Determining Performance Strength of Geomembranes by the Wide Strip Tensile Method
SIGNIFICANCE AND USE
This test method is a performance test intended as a design aid used to determine the ability of geomembranes to withstand the stresses and strains imposed under design conditions. This test method assists the design engineer in comparing several candidate geomembranes under specific test conditions.
As a performance test, this method is not intended for routine acceptance testing of commercial shipments of geomembranes. Other more easily performed test methods, such as Test Methods D751 or Test Method D882, can be used for routine acceptance testing of geomembranes. This test method will be used relatively infrequently, and to establish performance characteristics of geomembrane materials.
There is no known correlation between this test method and index test methods, such as Test Methods D751.
All geomembranes can be tested by this method. Some modification of techniques may be necessary for a given geomembrane depending upon its physical make-up. Special adaptations may be necessary with strong geomembranes or geomembranes with extremely slick surfaces, to prevent them from slipping in the clamps or being damaged by the clamps.
SCOPE
1.1 This test method covers the determination of the performance strength of synthetic geomembranes by subjecting wide strips of material to tensile loading.
1.2 This test method covers the measurement of tensile strength and elongation of geomembranes and includes directions for calculating initial modulus, offset modulus, secant modulus, and breaking toughness.
1.3 The basic distinctions between this test method and other methods measuring tensile strength of geomembranes are the width of the specimens tested and the speed of applied force. The greater width of the specimens specified in this test method minimizes the contraction edge effect (necking) which occurs in many geosynthetics and provides a closer relationship to actual material behavior in service. The slower speed of applied strain also provides a closer relationship to actual material behavior in service.
1.4 As a performance test, this method will be used relatively infrequently, and to test large lots of material. This test method is not intended for routine quality control testing of geomembranes.
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.6 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: D4885 − 01 (Reapproved 2011)
Standard Test Method for
Determining Performance Strength of Geomembranes by
the Wide Strip Tensile Method
This standard is issued under the fixed designation D4885; 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.
1. Scope 2. Referenced Documents
1.1 This test method covers the determination of the perfor- 2.1 ASTM Standards:
mance strength of synthetic geomembranes by subjecting wide D76 Specification for Tensile Testing Machines for Textiles
strips of material to tensile loading. D123 Terminology Relating to Textiles
D751 Test Methods for Coated Fabrics
1.2 This test method covers the measurement of tensile
D882 Test Method for Tensile Properties of Thin Plastic
strength and elongation of geomembranes and includes direc-
Sheeting
tions for calculating initial modulus, offset modulus, secant
D1593 Specification for Nonrigid Vinyl Chloride Plastic
modulus, and breaking toughness.
Film and Sheeting
1.3 The basic distinctions between this test method and
D1909 Standard Tables of Commercial Moisture Regains
othermethodsmeasuringtensilestrengthofgeomembranesare
and Commercial Allowances for Textile Fibers
the width of the specimens tested and the speed of applied
D4354 Practice for Sampling of Geosynthetics and Rolled
force. The greater width of the specimens specified in this test
Erosion Control Products(RECPs) for Testing
method minimizes the contraction edge effect (necking) which
D4439 Terminology for Geosynthetics
occurs in many geosynthetics and provides a closer relation-
3. Terminology
ship to actual material behavior in service.The slower speed of
applied strain also provides a closer relationship to actual
3.1 Definitions:
material behavior in service.
3.1.1 atmosphere for testing geomembranes, n—air main-
tained at a relative humidity of 50 to 70 % and a temperature
1.4 As a performance test, this method will be used rela-
of 21 6 2°C (70 6 4°F).
tively infrequently, and to test large lots of material. This test
3.1.1.1 Discussion—Within the range of 50 to 70 % relative
method is not intended for routine quality control testing of
humidity, moisture content is not expected to affect the tensile
geomembranes.
properties of geomembrane materials. In addition, geotextile
1.5 The values stated in SI units are to be regarded as
standard test methods restrict the range of relative humidity to
standard. The values given in parentheses are for information
65 6 5 %, while geomembrane standard test methods restrict
only.
the range of relative humidity to 55 6 5 %. The restricted
1.6 This standard does not purport to address all of the
rangeinthistestmethodismadebroadertoreducetheneedfor
safety concerns, if any, associated with its use. It is the
testing laboratories to change laboratory conditions, and con-
responsibility of the user of this standard to establish appro-
sidering the lack of expected effect of moisture on geomem-
priate safety and health practices and determine the applica-
branes. The user should consult Table D1909 to resolve
bility of regulatory limitations prior to use.
questions regarding moisture regains of textile fibers, espe-
cially if the user is testing a new or unknown material.
3.1.2 breaking force, (F), J, n—the force at failure.
This test method is under the jurisdiction of ASTM Committee D35 on
GeosyntheticsandisthedirectresponsibilityofSubcommitteeD35.10onGeomem-
branes. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
CurrenteditionapprovedJune1,2011.PublishedJuly2011.Originallyapproved contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
in 1988. Last previous edition approved in 2006 as D4885 – 06. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D4885-01R11. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4885 − 01 (2011)
−1 −2 −1 −1
3.1.3 breaking toughness, T, (FL ), Jm , n—for 3.1.12 initial tensile modulus, J, (FL ), Nm , n—for
i
geosynthetics, the actual work per unit volume of a material geosynthetics, the ratio of the change in force per unit width to
the change in elongation of the initial portion of a force-
corresponding to the breaking force.
elongation curve.
3.1.3.1 Discussion—Breaking toughness is proportional to
−1 −1
the area under the force-elongation curve from the origin to the
3.1.13 offset modulus, J , (FL ), Nm , n—for
o
breakingpoint(seealso,work-to-break).Breakingtoughnessis
geosynthetics, the ratio of the change in force per unit width to
calculated from work-to-break and width of a specimen. In
the change in elongation below an arbitrary offset point at
geomembranes, breaking toughness is often expressed as force
which there is a proportional relationship between force and
per unit width of material in inch-pound values. In other
elongation, and above the inflection point on the force-
materials, breaking toughness is often expressed as work per
elongation curve.
unit mass of material.
3.1.14 performance test, n—a test which simulates in the
3.1.4 corresponding force, n—synonym for force at speci- laboratory as closely as practicable selected conditions expe-
fied elongation.
riencedinthefieldandwhichcanbeusedindesign.(Synonym
for design test.)
3.1.5 elastic limit, n—in mechanics, the stress intensity at
−1 −1
3.1.15 secant modulus, J , (FL ), Nm , n—for
which stress and deformation of a material subjected to an
sec
increasing force cease to be proportional; the limit of stress geosynthetics, the ratio of change in force per unit width to the
change in elongation between two points on a force-elongation
withinwhichamaterialwillreturntoitsoriginalsizeandshape
curve.
when the force is removed, and hence, not a permanent set.
3.1.16 tensile, adj—capable of tensions, or relating to ten-
3.1.6 failure, n—an arbitrary point beyond which a material
sion of a material.
ceases to be functionally capable of its intended use.
−1 −1
3.1.6.1 Discussion—In wide strip tensile testing of
3.1.17 tensile modulus, J, (FL ), Nm , n—for
geosynthetics, failureoccurseitherattherupturepointoratthe
geosynthetics, the ratio of the change in tensile force per unit
yield point in the force-elongation curve, whichever occurs
width to a corresponding change in elongation.
first. For reinforced geomembranes, failure occurs at rupture of
3.1.18 tensile strength, n—the maximum resistance to de-
the reinforcing fabric. For nonreinforced geomembranes which
formation developed by a specific material when subjected to
exhibit a yield point, such as polyethylene materials, failure
tension by an external force.
occurs at the yield point. Even though the geomembrane
3.1.19 tensile test, n— for geosynthetics, a test in which a
continues to elongate, the force-elongation relationship has
material is stretched uniaxially to determine the force-
been irreversibly altered. For nonreinforced geomembranes
elongation characteristics, the breaking force, or the breaking
which do not exhibit a yield point, such as plasticized PVC
elongation.
materials, failure occurs at rupture of the geomembrane.
3.1.20 tension, n—the force that produces a specified elon-
3.1.7 force at specified elongation, FASE, n—a force asso-
gation.
ciated with a specific elongation on the force-elongation curve.
(Synonym for corresponding force.)
3.1.21 wide strip tensile test, n— for geosynthetics, a tensile
test in which the entire width of a 200 mm (8.0 in.) wide
3.1.8 force-elongationcurve,n—inatensiletest,agraphical
specimen is gripped in the clamps and the gauge length is
representation of the relationship between the magnitude of an
100 mm (4.0 in.).
externally applied force and the change in length of the
specimen in the direction of the applied force. (Synonym for
3.1.22 work-to-break, W, (LF), J, n—in tensile testing, the
stress-strain curve.)
total energy required to rupture a specimen.
3.1.22.1 Discussion—For geomembranes, work-to-break is
3.1.9 geomembrane, n—An essentially impermeable geo-
proportional to the area under the force-elongation curve from
synthetic used with foundation soil, rock, earth, or any other
the origin to the breaking point.
geotechnical engineering related material as an integral part of
a man-made project, structure, or system.
3.1.23 yield point, n— in geosynthetics, the point on the
3.1.9.1 Discussion—Other names under which geomem-
force-elongation curve at which the first derivative equals zero
branes are recognized include: flexible membrane liners
(the first maximum).
(fml’s), liners, and membranes.
3.1.24 For definitions of other terms used in this test
3.1.10 index test, n—a test procedure which may contain a
method, refer to Terminologies D123 and D4439.
known bias, but which may be used to establish an order for a
set of specimens with respect to the property of interest.
4. Summary of Test Method
3.1.11 inflection point, n—the first point of the force-
4.1 A relatively wide specimen is gripped across its entire
elongation curve at which the second derivative equals zero.
width in the clamps of a constant rate of extension type tensile
3.1.11.1 Discussion—The inflection point occurs at the first testing machine operated at a prescribed rate of extension,
point on the force-elongation curve at which the curve ceases applying a uniaxial load to the specimen until the specimen
to curve upward and begins to curve downward (or vice versa). ruptures. Tensile strength, elongation, initial and secant
D4885 − 01 (2011)
modulus, and breaking toughness of the test specimen can be machine direction from each roll in the lot sample. The sample
calculated from machine scales, dials, recording charts, or an may be taken from the end portion of a roll provided there is
interfaced computer. no evidence it is distorted or different from other portions of
the roll.
5. Significance and Use
7.3 Test Specimens—Take a total of twelve specimens from
5.1 This test method is a performance test intended as a
each swatch in the laboratory sample, with six specimens for
design aid used to determine the ability of geomembranes to
tests in the machine direction and six specimens for tests in the
withstand the stresses and strains imposed under design con-
cross-machine direction. Take the specimens from a diagonal
ditions. This test method assists the design engineer in com-
on the swatch with no specimen nearer the edge of the
paring several candidate geomembranes under specific test
geomembrane than 1/10 of the width of the geomembrane. Cut
conditions.
each specimen 200 mm (8.0 in.) wide by at least 200 mm
(8.0 in.) long with the length precisely aligned with the
5.2 As a performance test, this method is not intended for
direction in which the specimen is to be tested. The specimens
routine acceptance testing of commercial shipments of
mustbelongenoughtoextendcompletelythroughbothclamps
geomembranes. Other more easily performed test methods,
of the testing machine. Draw two parallel lines near the center
such as Test Methods D751 or Test Method D882, can be used
of each specimen length that (1) are separated by 100 mm (4.0
for routine acceptance testing of geomembranes. This test
in.), (2) extend the full width of the specimen, and (3) are
method will be used relatively infrequently, and to establish
performance characteristics of geomembrane materials. exactly perpendicular to the length of the specimen. Exercise
the utmost care in selecting, cutting, and preparing specimens
5.2.1 There is no known correlation between this test
method and index test methods, such as Test Methods D751. to avoid nicks, tears, scratches, folds, or other imperfections
that are likely to cause premature failure.
5.3 All geomembranes can be tested by this method. Some
modification of techniques may be necessary for a given
8. Conditioning
geomembrane depending upon its physical make-up. Special
adaptations may be necessary with strong geomembranes or
8.1 Expose the specimens to the standard atmosphere for
geomembranes with extremely slick surfaces, to prevent them
testing geomembranes for a period long enough to allow the
from slipping in the clamps or being damaged by the clamps.
geomembrane to reach equilibrium with the standard atmo-
sphere. Consider the specimen to be at moisture equilibrium
6. Apparatus
when the change in mass of the specimen in successive
weighings made at intervals of not less than 2 h does not
6.1 Clamps—A gripping system that minimizes (with the
exceed 0.1 % of the mass of the specimen. Consider the
goal of eliminating) slippage, damage to the specimen, and
specimentobeattemperatureequilibriumafter1hofexposure
uneven stress distribution. The gripping system shall extend to
to the standard atmosphere for testing.
or beyond the outer edge of the specimen to be tested.
6.2 Specimen Cutter—An appropriate cutting device which
9. Procedure
doesnotcreateirregularitiesorimperfectionsintheedgeofthe
specimen.Forwidestripspecimens,ajigmaynotbenecessary 9.1 Test adequately conditioned specimens. Conduct tests at
provided that the actual cut dimensions of the specimen can be
a temperature of 21 6 2°C (70 6 4°F) and at a relative
measured accurately to the nearest 1.0 mm (0.04 in.), and that humidity of 50 to 70 %. The engineer may specify additional
the width of the specimen is constant to within 1.0 mm
temperatures based upon expected service conditions for the
(0.04 in.). installation.
6.3 Tensile Testing Machine—A testing machine of the
9.2 Measure for the specimens thickness at the four corners
constant rate of extension type as described in Specification
of the specimen. Select specimens used in this procedure so
D76 shall be used. The machine shall be equipped with a
that thickness is uniform to within 5 %. Measure thickness
device for recording the tensile force and the amount of
using either Specification D1593 for nonreinforced geomem-
separation of the grips. Both of these measuring systems shall
branes or Test Methods D751 for reinforced geomembranes.
be accurate to 62 % and, preferably, shall be external to the
9.3 Positionthegripsofthetestingapparatustoaseparation
testing machine. The rate of separation shall be uniform and
of 100 63mm(4 6 0.1 in.). At least one clamp should be
capable of adjustment within the range of the test.
supported by a free swivel or universal joint which will allow
the clamp to rotate in the plane of the fabric. Select the force
7. Sampling
range of the
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