ASTM D4595-86(1994)
(Test Method)Standard Test Method for Tensile Properties of Geotextiles by the Wide-Width Strip Method
Standard Test Method for Tensile Properties of Geotextiles by the Wide-Width Strip Method
SCOPE
1.1 This test method covers the measurement of tensile properties of geotextiles using a wide-width strip specimen tensile method. This test method is applicable to most geotextiles that include woven fabrics, nonwoven fabrics, layered fabrics, knit fabrics, and felts that are used for geotextile application.
1.2 This test method covers the measurement of tensile strength and elongation of geotextiles and includes directions for the calculation of initial modulus, offset modulus, secant modulus, and breaking toughness.
1.3 Procedures for measuring the tensile properties of both conditioned and wet geotextiles by the wide-width strip method are included.
1.4 The basic distinction between this test method and other methods for measuring strip tensile properties is the width of the specimen. This width, by contrast, is greater than the length of the specimen. Some fabrics used in geotextile applications have a tendency to contract (neck down) under a force in the gage length area. The greater width of the specimen specified in this test method minimizes the contraction effect of those fabrics and provides a closer relationship to expected geotextile behavior in the field and a standard comparison.
1.5 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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Designation: D 4595 – 86 (Reapproved 1994)
Standard Test Method for
Tensile Properties of Geotextiles by the Wide-Width Strip
Method
This standard is issued under the fixed designation D 4595; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 4439 Terminology for Geosynthetics
1.1 This test method covers the measurement of tensile
3. Terminology
properties of geotextiles using a wide-width strip specimen
3.1 atmosphere for testing geotextiles, n.—air maintained at
tensile method. This test method is applicable to most geotex-
a relative humidity of 65 6 5 % and a temperature of 21 6 2°C
tiles that include woven fabrics, nonwoven fabrics, layered
(70 6 4°F).
fabrics, knit fabrics, and felts that are used for geotextile
−1 −2
3.2 breaking toughness, T, (FL ), Jm , n.—for geotextiles,
application.
the actual work-to-break per unit surface area of material.
1.2 This test method covers the measurement of tensile
3.2.1 Discussion—Breaking toughness is proportional to
strength and elongation of geotextiles and includes directions
the area under the force − elongation curve from the origin to
for the calculation of initial modulus, offset modulus, secant
the breaking point (see also work-to-break). Breaking tough-
modulus, and breaking toughness.
ness is calculated from work-to-break, gage length, and width
1.3 Procedures for measuring the tensile properties of both
of a specimen.
conditioned and wet geotextiles by the wide-width strip
3.3 corresponding force, F ,n.—the force associated with a
c
method are included.
specific elongation on the force-per-unit-width strain curve.
1.4 The basic distinction between this test method and other
(Syn. load at specified elongation, LASE.)
methods for measuring strip tensile properties is the width of
3.4 geotechnical engineering, n.—the engineering applica-
the specimen. This width, by contrast, is greater than the length
tion of geotechnics.
of the specimen. Some fabrics used in geotextile applications
3.5 geotechnics, n.—the application of scientific methods
have a tendency to contract (neck down) under a force in the
and engineering principles to the acquisition, interpretation,
gage length area. The greater width of the specimen specified
and use of knowledge of materials of the earth’s crust to the
in this test method minimizes the contraction effect of those
solution of engineering problems.
fabrics and provides a closer relationship to expected geotextile
3.5.1 Discussion—Geotechnics embraces the fields of soil
behavior in the field and a standard comparison.
mechanics, rock mechanics, and many of the engineering
1.5 This standard does not purport to address all of the
aspects of geology, geophysics, hydrology, and related sci-
safety concerns, if any, associated with its use. It is the
ences.
responsibility of the user of this standard to establish appro-
3.6 geotextile, n.—any permeable textile material used with
priate safety and health practices and determine the applica-
foundation, soil, rock, earth, or any other geotechnical engi-
bility of regulatory limitations prior to use.
neering related material, as an integral part of a man-made
2. Referenced Documents project, structure, or system.
−1 −1
3.7 initial tensile modulus, J , (FL ), Nm , n.—for geo-
i
2.1 ASTM Standards:
textiles, the ratio of the change in tensile force per unit width
D 76 Specification for Tensile Testing Machines for Tex-
to a change in strain (slope) of the initial portion of a force per
tiles
2 unit width strain curve.
D 123 Definitions of Terms Relating to Textiles
−1 −1
3.8 offset tensile modulus, J , (FL ), Nm , n.—for geo-
o
D 579 Specification for Greige Woven Glass Fabrics
2 textiles, the ratio of the change in force per unit width to a
D 1776 Practice for Conditioning Textiles for Testing
change in strain (slope) below the proportional limit point and
D 2905 Practice for Statements on Number of Specimens
2 above the tangent point on the force − elongation curve.
for Textiles
3.9 proportional limit, n.—the greatest stress which a ma-
terial is capable of sustaining without any deviation from
This test method is under the jurisdiction of ASTM Committee D-35 on
proportionality of stress to strain (Hooke’s law).
Geosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-
−1 −1
cal Properties. 3.10 secant tensile modulus, J (FL ), Nm , n.—for
sec
Current edition approved Sept. 24, 1986. Published November 1986.
Annual Book of ASTM Standards, Vol 07.01.
Annual Book of ASTM Standards, Vol 04.09.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 4595
geotextiles, the ratio of change in force per unit width to a Method D 4595 for the determination of the wide-width strip
change in strain (slope) between two points on a force per unit tensile properties of geotextiles may be used for the acceptance
width strain curve. testing of commercial shipments of geotextiles but caution is
3.11 tangent point, n.—for geotextiles, the first point of the advised since information about between-laboratory precision
force − elongation curve at which a major decrease in slope is incomplete (Note 6). Comparative tests as directed in 5.1.1
occurs. may be advisable.
3.11.1 Discussion—The tangent point is determined by 5.1.1 In cases of a dispute arising from differences in
drawing a tangent line passing through the zero axis and the reported test results when using Test Method D 4595 for
proportional elastic limit. The point from the zero force axis acceptance testing of commercial shipments, the purchaser and
that the force − elongation curve first touches that tangent line the supplier should conduct comparative tests to determine if
is the tangent point. there is a statistical bias between their laboratories. Competent
−1 −1
3.12 tensile modulus, J, (FL ), Nm , n.—for geotextiles, statistical assistance is recommended for the investigation of
the ratio of the change in tensile force per unit width to a bias. As a minimum, the two parties should take a group of test
corresponding change in strain (slope). specimens which are as homogeneous as possible and which
3.13 tensile strength, n.—for geotextiles, the maximum are from a lot of material of the type in question. The test
resistance to deformation developed for a specific material specimens should then be randomly assigned in equal numbers
when subjected to tension by an external force. to each laboratory for testing. The average results from the two
3.13.1 Discussion—Tensile strength of geotextiles is the laboratories should be compared using Student’s t-test for
characteristic of a sample as distinct from a specimen and is unpaired data and an acceptable probability level chosen by the
expressed in force per unit width. two parties before the testing began. If a bias is found, either its
3.14 tensile test, n.—in textiles, a test in which a textile cause must be found and corrected or the purchaser and the
material is stretched in one direction to determine the supplier must agree to interpret future test results in the light of
force − elongation characteristics, the breaking force, or the the known bias.
breaking elongation. 5.2 Most geotextiles can be tested by this test method. Some
3.15 wide-width strip tensile test, n.—for geotextiles,a modification of clamping techniques may be necessary for a
uniaxial tensile test in which the entire width of a 200-mm given geotextile depending upon its structure. Special clamp-
(8.0-in.) wide specimen is gripped in the clamps and the gage ing adaptions may be necessary with strong geotextiles or
length is 100 mm (4.0 in.). geotextiles made from glass fibers to prevent them from
3.16 work-to-break, W, (LF), n.—in tensile testing, the total slipping in the clamps or being damaged as a result of being
energy required to rupture a specimen. gripped in the clamps. Specimen clamping may be modified as
3.16.1 Discussion—For geotextiles, work-to-break is pro- required at the discretion of the individual laboratory providing
portional to the area under the force − elongation curve from a representative tensile strength is obtained. In any event, the
the origin to the breaking point, and is commonly expressed in procedure described in Section 10 of this test method for
joules (inch-pound-force). obtaining wide-width strip tensile strength must be maintained.
3.17 yield point, n.—the first point of the force − elongation 5.3 This test method is applicable for testing geotextiles
curve above the proportional (linear) section at which an either dry or wet. It is used with a constant rate of extension
increase in elongation occurs without a corresponding increase type tension apparatus.
in force. 5.4 The use of tensile strength test methods that restrict the
3.18 For terminology of other terms used in this test clamped width dimension to 50 mm (2 in.) or less, such as the
method, refer to Terminology D 123 and Terminology D 4439. ravel, cut strip, and grab test procedures, have been found less
suitable than this test method for determining design strength
4. Summary of Method
parameters for some geotextiles. This is particularly the case
4.1 A relatively wide specimen is gripped across its entire for nonwoven geotextiles. The wide-width strip technique has
width in the clamps of a constant rate of extension (CRE) type
been explored by the industry and is recommended in these
tensile testing machine operated at a prescribed rate of exten- cases for geotextile applications.
sion, applying a longitudinal force to the specimen until the
5.4.1 This test method may not be suited for some woven
specimen ruptures. Tensile strength, elongation, initial and fabrics used in geotextile applications that exhibit strengths
secant modulus, and breaking toughness of the test specimen
approximately 100 kN/m or 600 lbf/in. due to clamping and
can be calculated from machine scales, dials, recording charts,
equipment limitations. In those cases, 100-mm (4-in.) width
or an interfaced computer.
specimens may be substituted for 200-mm (8-in.) width speci-
mens. On those fabrics, the contraction effect cited in 1.4 is
5. Significance and Use
minimal and, consequently, the standard comparison can con-
5.1 The determination of the wide-width strip
tinue to be made.
force − elongation properties of geotextiles provides design
6. Apparatus and Reagents
parameters for reinforcement type applications, for example
design of reinforced embankments over soft subgrades, rein- 6.1 Tensile Testing Machine—A constant rate of extension
forced soil retaining walls, and reinforcement of slopes. When (CRE) type of testing machine described in Specification D 76
strength is not necessarily a design consideration, an alterna- shall be used. When using the CRE type tensile tester, the
tive test method may be used for acceptance testing. Test recorder must have adequate pen response to properly record
D 4595
the force—elongation curve as specified in Specification D 76. upon between the purchaser and the supplier.
6.2 Clamps—The clamps shall be sufficiently wide to grip
NOTE 1—The extent of the sampling for wide-width strip tensile
the entire width of the sample and with appropriate clamping
properties is generally defined in an applicable order or contract. Among
power to prevent slipping or crushing (damage).
the options available to the purchaser and the supplier is for the purchaser
6.2.1 Two basic clamp designs are shown in Fig. 1, Fig. 2,
to accept certification by the manufacturer that the material in question
Fig. 3, and Fig. 4. These designs have been used in the
meets the requirements agreed upon by the two parties, and what the basis
laboratory and have provided reproducible tensile strengths.
for the certification is, such as, historical data generated from material
manufactured under the same conditions.
These clamps may be modified to provide greater ease and
speed of clamping. In any event, caution must be taken to
7.2 Laboratory Sample—For the laboratory sample, take a
ensure the type material and dimensions of the clamp are
full-width swatch approximately 1 m (40 in.) long in the
adequate for the user’s expected fabric strength.
machine direction from each roll in the lot sample. The sample
6.2.2 Size of Jaw Faces—Each clamp shall have jaw faces
may be taken from the end portion of a roll provided there is
measuring wider than the width of the specimen, 200 mm (8
no evidence it is distorted or different from other portions of
in.), and a minimum of 50-mm (2-in.) length in the direction of
the roll. In cases of dispute, take a sample that will exclude
the applied force.
fabric from the outer wrap of the roll or the inner wrap around
6.3 Area-Measuring Device—Use an integrating accessory
the core.
to the tensile testing machine or a planimeter.
7.3 Test Specimens—For tests in the machine direction and
6.4 Distilled Water and Nonionic Wetting Agent, for wet
the cross-machine direction, respectively, take from each
specimens only.
swatch in the laboratory sample the number of specimens
7. Sampling
directed in Section 8. Take specimens at random from the
laboratory sample, with those for the measurement of the
7.1 Lot Sample—For the lot sample, take rolls of geotextiles
as directed in an applicable material specification, or as agreed machine direction tensile properties from different positions
FIG. 1 Wide Width Test Clamps
D 4595
FIG. 2 Inserts for Wide Width Clamps
across the geotextile width, and the specimens for the mea-
where:
surement of the cross-machine direction tensile properties from
n 5 number of specimens (rounded upward to a whole
different positions along the length of the geotextile. Take no number),
v 5 reliable estimate of the coefficient of variation of
specimens nearer the selvage or edge of the geotextile than
individual observations on similar materials in the
1/10 the width of the geotextile (see 8.2).
user’s laboratory under conditions of single-operator
precision, %,
8. Test Specimen Preparation
t 5 the value of Student’s t for one-sided limits (see Table
8.1 Number of Specimens:
1), a 95 % probability level, and the degrees of
8.1.1 Unless otherwise agreed upon, as when specified in an freedom associated with the estimate of v, and
A 5 5.0 % of the average, the value of the allowable
applicable material specification, take a number of specimens
variation.
per fabric swatch such that the
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