ASTM D4885-01(2006)
(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 D 751 or Test Method D 882, 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.
5.2.1 There is no known correlation between this test method and index test methods, such as Test Methods D 751.
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 the standard. The values given in parentheses are for information only.
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 2006)
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 D123 Terminology Relating to Textiles
D751 Test Methods for Coated Fabrics
1.1 This test method covers the determination of the perfor-
D882 Test Method for Tensile Properties of Thin Plastic
mance strength of synthetic geomembranes by subjecting wide
Sheeting
strips of material to tensile loading.
D1593 Specification for Nonrigid Vinyl Chloride Plastic
1.2 This test method covers the measurement of tensile
Film and Sheeting
strength and elongation of geomembranes and includes direc-
D1909 StandardTable of Commercial Moisture Regains for
tions for calculating initial modulus, offset modulus, secant
Textile Fibers
modulus, and breaking toughness.
D4354 Practice for Sampling of Geosynthetics for Testing
1.3 The basic distinctions between this test method and
D4439 Terminology for Geosynthetics
othermethodsmeasuringtensilestrengthofgeomembranesare
the width of the specimens tested and the speed of applied
3. Terminology
force. The greater width of the specimens specified in this test
3.1 Definitions:
method minimizes the contraction edge effect (necking) which
3.1.1 atmosphere for testing geomembranes, n—air main-
occurs in many geosynthetics and provides a closer relation-
tained at a relative humidity of 50 to 70 % and a temperature
ship to actual material behavior in service.The slower speed of
of 21 6 2°C (70 6 4°F).
applied strain also provides a closer relationship to actual
3.1.1.1 Discussion—Within the range of 50 to 70 % relative
material behavior in service.
humidity, moisture content is not expected to affect the tensile
1.4 As a performance test, this method will be used rela-
properties of geomembrane materials. In addition, geotextile
tively infrequently, and to test large lots of material. This test
standard test methods restrict the range of relative humidity to
method is not intended for routine quality control testing of
65 6 5 %, while geomembrane standard test methods restrict
geomembranes.
the range of relative humidity to 55 6 5 %. The restricted
1.5 The values stated in SI units are to be regarded as
rangeinthistestmethodismadebroadertoreducetheneedfor
standard. The values given in parentheses are for information
testing laboratories to change laboratory conditions, and con-
only.
sidering the lack of expected effect of moisture on geomem-
1.6 This standard does not purport to address all of the
branes. The user should consult Table D1909 to resolve
safety concerns, if any, associated with its use. It is the
questions regarding moisture regains of textile fibers, espe-
responsibility of the user of this standard to establish appro-
cially if the user is testing a new or unknown material.
priate safety and health practices and determine the applica-
3.1.2 breaking force, (F), J, n—the force at failure.
bility of regulatory limitations prior to use.
−1 −2
3.1.3 breaking toughness, T, (FL ), Jm , n—for geosyn-
2. Referenced Documents thetics, the actual work per unit volume of a material corre-
sponding to the breaking force.
2.1 ASTM Standards:
3.1.3.1 Discussion—Breaking toughness is proportional to
D76 Specification for Tensile Testing Machines for Textiles
the area under the force-elongation curve from the origin to the
breakingpoint(seealso,work-to-break).Breakingtoughnessis
This test method is under the jurisdiction of ASTM Committee D35 on
calculated from work-to-break and width of a specimen. In
GeosyntheticsandisthedirectresponsibilityofSubcommitteeD35.10onGeomem-
geomembranes, breaking toughness is often expressed as force
branes.
per unit width of material in inch-pound values. In other
Current edition approved June 1, 2006. Published June 2006. Originally
approved in 1988. Last previous edition approved in 2001 as D4885 – 01. DOI:
materials, breaking toughness is often expressed as work per
10.1520/D4885-01R06.
unit mass of material.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.1.4 corresponding force, n—synonym for force at speci-
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 fied elongation.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4885–01 (2006)
3.1.5 elastic limit, n—in mechanics, the stress intensity at 3.1.16 tensile, adj—capable of tensions, or relating to ten-
which stress and deformation of a material subjected to an sion of a material.
−1 −1
increasing force cease to be proportional; the limit of stress 3.1.17 tensile modulus, J, (FL ), Nm , n—for geosynthet-
withinwhichamaterialwillreturntoitsoriginalsizeandshape ics, the ratio of the change in tensile force per unit width to a
when the force is removed, and hence, not a permanent set. corresponding change in elongation.
3.1.6 failure, n—an arbitrary point beyond which a material 3.1.18 tensile strength, n—the maximum resistance to de-
formation developed by a specific material when subjected to
ceases to be functionally capable of its intended use.
tension by an external force.
3.1.6.1 Discussion—In wide strip tensile testing of geosyn-
3.1.19 tensile test, n— for geosynthetics, a test in which a
thetics, failure occurs either at the rupture point or at the yield
material is stretched uniaxially to determine the force-
point in the force-elongation curve, whichever occurs first. For
elongation characteristics, the breaking force, or the breaking
reinforced geomembranes, failure occurs at rupture of the
elongation.
reinforcing fabric. For nonreinforced geomembranes which
3.1.20 tension, n—the force that produces a specified elon-
exhibit a yield point, such as polyethylene materials, failure
gation.
occurs at the yield point. Even though the geomembrane
3.1.21 widestriptensiletest,n—forgeosynthetics,atensile
continues to elongate, the force-elongation relationship has
test in which the entire width of a 200 mm (8.0 in.) wide
been irreversibly altered. For nonreinforced geomembranes
specimen is gripped in the clamps and the gauge length is
which do not exhibit a yield point, such as plasticized PVC
100 mm (4.0 in.).
materials, failure occurs at rupture of the geomembrane.
3.1.22 work-to-break, W, (LF), J, n—in tensile testing, the
3.1.7 force at specified elongation, FASE, n—a force asso-
total energy required to rupture a specimen.
ciated with a specific elongation on the force-elongation curve.
3.1.22.1 Discussion—For geomembranes, work-to-break is
(Synonym for corresponding force.)
proportional to the area under the force-elongation curve from
3.1.8 force-elongation curve, n—in a tensile test, a graphi-
the origin to the breaking point.
cal representation of the relationship between the magnitude of
3.1.23 yield point, n—in geosynthetics, the point on the
an externally applied force and the change in length of the
force-elongation curve at which the first derivative equals zero
specimen in the direction of the applied force. (Synonym for
(the first maximum).
stress-strain curve.)
3.1.24 For definitions of other terms used in this test
3.1.9 geomembrane, n—An essentially impermeable geo-
method, refer to Terminologies D123 and D4439.
synthetic used with foundation soil, rock, earth, or any other
geotechnical engineering related material as an integral part of
4. Summary of Test Method
a man-made project, structure, or system.
4.1 A relatively wide specimen is gripped across its entire
3.1.9.1 Discussion—Other names under which geomem-
width in the clamps of a constant rate of extension type tensile
branes are recognized include: flexible membrane liners
testing machine operated at a prescribed rate of extension,
(fml’s), liners, and membranes.
applying a uniaxial load to the specimen until the specimen
3.1.10 index test, n—a test procedure which may contain a
ruptures. Tensile strength, elongation, initial and secant modu-
known bias, but which may be used to establish an order for a
lus, and breaking toughness of the test specimen can be
set of specimens with respect to the property of interest.
calculated from machine scales, dials, recording charts, or an
3.1.11 inflection point, n—the first point of the force-
interfaced computer.
elongation curve at which the second derivative equals zero.
3.1.11.1 Discussion—The inflection point occurs at the first 5. Significance and Use
point on the force-elongation curve at which the curve ceases
5.1 This test method is a performance test intended as a
to curve upward and begins to curve downward (or vice versa).
design aid used to determine the ability of geomembranes to
−1 −1
3.1.12 initial tensile modulus, J, (FL ), Nm , n—for
i
withstand the stresses and strains imposed under design con-
geosynthetics, the ratio of the change in force per unit width to
ditions. This test method assists the design engineer in com-
the change in elongation of the initial portion of a force-
paring several candidate geomembranes under specific test
elongation curve.
conditions.
−1 −1
3.1.13 offset modulus, J , (FL ), Nm , n—for geosyn-
5.2 As a performance test, this method is not intended for
o
thetics, the ratio of the change in force per unit width to the
routine acceptance testing of commercial shipments of
change in elongation below an arbitrary offset point at which
geomembranes. Other more easily performed test methods,
there is a proportional relationship between force and elonga-
such as Test Methods D751 or Test Method D882, can be used
tion, and above the inflection point on the force-elongation
for routine acceptance testing of geomembranes. This test
curve.
method will be used relatively infrequently, and to establish
3.1.14 performance test, n—a test which simulates in the
performance characteristics of geomembrane materials.
laboratory as closely as practicable selected conditions expe-
5.2.1 There is no known correlation between this test
riencedinthefieldandwhichcanbeusedindesign.(Synonym
method and index test methods, such as Test Methods D751.
for design test.)
5.3 All geomembranes can be tested by this method. Some
−1 −1
3.1.15 secantmodulus,J ,(FL ),Nm ,n—forgeosyn- modification of techniques may be necessary for a given
sec
thetics,theratioofchangeinforceperunitwidthtothechange geomembrane depending upon its physical make-up. Special
in elongation between two points on a force-elongation curve. adaptations may be necessary with strong geomembranes or
D4885–01 (2006)
geomembranes with extremely slick surfaces, to prevent them sphere. Consider the specimen to be at moisture equilibrium
from slipping in the clamps or being damaged by the clamps. when the change in mass of the specimen in successive
weighings made at intervals of not less than 2 h does not
6. Apparatus
exceed 0.1 % of the mass of the specimen. Consider the
6.1 Clamps—A gripping system that minimizes (with the specimentobeattemperatureequilibriumafter1hofexposure
goal of eliminating) slippage, damage to the specimen, and to the standard atmosphere for testing.
uneven stress distribution. The gripping system shall extend to
or beyond the outer edge of the specimen to be tested.
9. Procedure
6.2 Specimen Cutter—An appropriate cutting device which
9.1 Test adequately conditioned specimens. Conduct tests at
doesnotcreateirregularitiesorimperfectionsintheedgeofthe
a temperature of 21 6 2°C (70 6 4°F) and at a relative
specimen.Forwidestripspecimens,ajigmaynotbenecessary
humidity of 50 to 70 %. The engineer may specify additional
provided that the actual cut dimensions of the specimen can be
temperatures based upon expected service conditions for the
measured accurately to the nearest 1.0 mm (0.04 in.), and that
installation.
the width of the specimen is constant to within 1.0 mm
9.2 Measure for the specimens thickness at the four corners
(0.04 in.).
of the specimen. Select specimens used in this procedure so
6.3 Tensile Testing Machine—A testing machine of the
that thickness is uniform to within 5 %. Measure thickness
constant rate of extension type as described in Specification
using either Specification D1593 for nonreinforced geomem-
D76 shall be used. The machine shall be equipped with a
branes or Test Methods D751 for reinforced geomembranes.
device for recording the tensile force and the amount of
9.3 Positionthegripsofthetestingapparatustoaseparation
separation of the grips. Both of these measuring systems shall
of 100 63mm(4 6 0.1 in.). At least one clamp should be
be accurate to 62 % and, preferably, shall be external to the
supported by a free swivel or universal joint which will allow
testing machine. The rate of separation shall be uniform and
capable of adjustment within the range of the test. the clamp to rotate in the plane of the fabric. Select the force
range of the testing machine so that the break occurs between
7. Sampling
10 and 90 % of full scale load. Set the machine to a strain rate
as directed in 9.6.
7.1 Lot Sample—Divide the product into lots and take the
lot sample as directed in Practice D4354. 9.4 Mount the specimen centrally in the clamps. Do this by
7.2 Laboratory Sample—For the laboratory sample, take a having the two lines, which were previously drawn 100 6
full-width swatch approximately 1 m (40 in.) long in the 3 mm (4.0 6 0.1 in.) apart across the width of the specimen as
machine direction from each roll in the lot sample. The sample close as possible adjacent to the inside edges of the upper and
may be taken from the end portion of a roll provided there is lower jaw. The specimen length in the machine direction and
no evidence it is distorted or different from other portions of the cross machine direction tests, respectively, must be parallel
the roll. to the direction of application of force.
7.3 Test Specimens—Take a total of twelve specimens from
9.5 Start the tensile testing machine and the area measuring
each swatch in the laboratory sample, with six specimens for
device, if used, and continue running the test to rupture. Stop
tests in the machine direction and six specimens for tests in the
the machine and reset to the initial gauge position. Record and
cross-machine direction. Take the specimens from a diagonal
report the test results to three significant figures for each
on the
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