ASTM D4632/D4632M-08(2013)e2
(Test Method)Standard Test Method for Grab Breaking Load and Elongation of Geotextiles
Standard Test Method for Grab Breaking Load and Elongation of Geotextiles
SIGNIFICANCE AND USE
5.1 The grab method is applicable whenever it is desired to determine the “effective strength” of the fabric in use, that is, the strength of the material in a specific width, together with the additional strength contributed by adjacent material. There is no simple relationship between grab tests and strip tests since the amount of fabric assistance depends on the construction of the fabric. It is useful as a quality control or acceptance test.
5.2 The procedure in Test Method D4632/D4632M for the determination of grab strength of geotextiles may be used for acceptance testing of commercial shipments, but caution is advised since information about between-laboratory precision is incomplete. Comparative tests as directed in 5.2.1 are advisable.
5.2.1 In case of a dispute arising from differences in reported test results when using the procedures in Test Method D4632/D4632M for acceptance testing of commercial shipments, the purchaser and the manufacturer should conduct comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens that are as homogeneous as possible and which are from a lot of material of the type in question. The test specimens should then be randomly assigned in equal numbers to each laboratory for testing. The average results from the two laboratories should be compared using the appropriate Student's t-test and an acceptable probability level chosen by the two parties before testing is begun. If a bias is found, either its cause must be found and corrected or the purchaser and the manufacturer must agree to interpret future test results in the light of the known bias.
5.3 Most geotextile fabrics can be tested by this test method. Some modification of clamping techniques may be necessary for a given fabric, depending upon its structure. Special adaptation may be nece...
SCOPE
1.1 This test method is an index test which provides a procedure for determining the breaking load (grab strength) and elongation (grab elongation) of geotextiles using the grab method. This test method is not suitable for knitted fabrics and alternate test methods should be used. While useful for quality control and acceptance testing for a specific fabric structure, the results can only be used comparatively between fabrics with very similar structures, because each different fabric structure performs in a unique and characteristic manner in this test. The grab test methods does not provide all the information needed for all design applications and other test methods should be used.
1.2 Procedures for measuring the breaking load and elongation by the grab method in both the dry and wet state are included; however, testing is normally done in the dry condition unless specified otherwise in an agreement or specification.
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 may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D4632/D4632M − 08(Reapproved 2013)
Standard Test Method for
Grab Breaking Load and Elongation of Geotextiles
This standard is issued under the fixed designation D4632/D4632M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
ε NOTE—Units information was editorially corrected in June 2013.
ε NOTE—Table 1 was editorially inserted in Section 8.1.1 in March 2014.
1. Scope 2. Referenced Documents
1.1 This test method is an index test which provides a 2.1 ASTM Standards:
D76/D76M Specification for Tensile Testing Machines for
procedure for determining the breaking load (grab strength)
and elongation (grab elongation) of geotextiles using the grab Textiles
D123 Terminology Relating to Textiles
method. This test method is not suitable for knitted fabrics and
alternate test methods should be used. While useful for quality D1776 Practice for Conditioning and Testing Textiles
D2905 Practice for Statements on Number of Specimens for
control and acceptance testing for a specific fabric structure,
the results can only be used comparatively between fabrics Textiles (Withdrawn 2008)
D4354 Practice for Sampling of Geosynthetics and Rolled
with very similar structures, because each different fabric
structure performs in a unique and characteristic manner in this Erosion Control Products(RECPs) for Testing
D4439 Terminology for Geosynthetics
test.The grab test methods does not provide all the information
needed for all design applications and other test methods
3. Terminology
should be used.
3.1 Definitions:
1.2 Procedures for measuring the breaking load and elon-
3.1.1 atmosphere for testing geotextiles, n—air maintained
gation by the grab method in both the dry and wet state are
at a relative humidity of 65 6 5 % relative humidity and
included; however, testing is normally done in the dry condi-
temperature of 21 6 2°C [70 6 4°F].
tion unless specified otherwise in an agreement or specifica-
3.1.2 breaking load, n—the maximum force applied to a
tion.
specimen in a tensile test carried to rupture.
1.3 The values stated in either SI units or inch-pound units
3.1.3 cross-machine direction, n—the direction in the plane
are to be regarded separately as standard. The values stated in
of the fabric perpendicular to the direction of manufacture.
each system may not be exact equivalents; therefore, each
3.1.4 elongation at break, n—the elongation corresponding
system shall be used independently of the other. Combining
to the breaking load, that is, the maximum load.
values from the two systems may result in non-conformance
with the standard.
3.1.5 geotextile, n—any permeable textile material used
with foundation, soil, rock, earth, or any other geotechnical
1.4 This standard does not purport to address all of the
material, as an integral part of a man-made product, structure,
safety concerns, if any, associated with its use. It is the
or system.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 3.1.6 grab test, n—in fabric testing, a tension test in which
bility of regulatory limitations prior to use.
only a part of the width of the specimen is gripped in the
clamps.
1 2
This test method is under the jurisdiction of ASTM Committee D35 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Geosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani- contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
cal Properties. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 1, 2013. Published June 2013. Originally the ASTM website.
approved in 1991. Last previous edition approved in 2008 as D4632–08. DOI: The last approved version of this historical standard is referenced on
10.1520/D4632_D4632M-08R13E02. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4632/D4632M − 08 (2013)
3.1.6.1 Discussion—For example, if the specimen width is However, there may be no overall correlation between the
101.6 mm [4 in.] and the width of the jaw faces 25.4 mm [1 results obtained with the CRT machine and the CRE machine.
in.], the specimen is gripped centrally in the clamps. Consequently, these two tension testers cannot be used inter-
changeably. In case of controversy, the CRE machine shall
3.1.7 machine direction, n—the direction in the plane of the
prevail.
fabric parallel to the direction of manufacture.
3.1.8 For definitions of other terms used in this test method,
6. Apparatus
refer to Terminology D123 or Terminology D4439.
6.1 Tensile Testing Machine, of the constant-rate-of-
extension (CRE) or constant-rate-of-traverse (CRT) type with
4. Summary of Test Method
autographic recorder conforming to the requirements of Speci-
4.1 A continually increasing load is applied longitudinally
fication D76/D76M.
to the specimen and the test is carried to rupture.Values for the
6.2 Clamps, having all gripping surfaces parallel, flat, and
breaking load and elongation of the test specimen are obtained
capable of preventing slipping of the specimen during a test.
from machine scales or dials, autographic recording charts, or
Each clamp shall have one jaw face measuring 25.4 by 50.8
interfaced computers.
mm [1 by 2 in.], with the longer dimension parallel to the
5. Significance and Use
direction of application of the load. The other jaw face of each
clamp shall be at least as large as its mate. Each jaw face shall
5.1 The grab method is applicable whenever it is desired to
be in line, both with respect to its mate in the same clamp and
determine the “effective strength” of the fabric in use, that is,
to the corresponding jaw of the other clamp.
the strength of the material in a specific width, together with
the additional strength contributed by adjacent material. There
7. Sampling and Selection
isnosimplerelationshipbetweengrabtestsandstriptestssince
the amount of fabric assistance depends on the construction of
7.1 Division into Lots and Lot Samples—Dividethematerial
the fabric. It is useful as a quality control or acceptance test.
into lots and take a lot sample as directed in Practice D4354.
Rolls of fabric are the primary sampling unit.
5.2 The procedure in Test Method D4632/D4632M for the
determination of grab strength of geotextiles may be used for
7.2 Laboratory Sample—Take for the laboratory sample a
acceptance testing of commercial shipments, but caution is
swatch extending the width of the fabric and approximately 1
advised since information about between-laboratory precision
m[39.37in.]alongtheselvagefromeachrollinthelotsample.
is incomplete. Comparative tests as directed in 5.2.1 are
The swatch may be taken from the end portion of a roll
advisable.
provided there is no evidence that it is distorted or different
5.2.1 In case of a dispute arising from differences in
from other portions of the roll. In cases of dispute, take a
reported test results when using the procedures in Test Method
swatch that will exclude fabric from the outer wrap of the roll
D4632/D4632M for acceptance testing of commercial
or the inner wrap around the core.
shipments, the purchaser and the manufacturer should conduct
7.3 Test Specimens—Cut the number of specimens from
comparative tests to determine if there is a statistical bias
each swatch in the laboratory sample determined as directed in
between their laboratories. Competent statistical assistance is
Section 8. Take no specimens nearer the selvage of fabric edge
recommended for the investigation of bias.As a minimum, the
than ⁄20 of the fabric width or 150 mm [6 in.], whichever is the
two parties should take a group of test specimens that are as
smaller. Cut rectangular specimens 101.6 by 203.2 mm [4 by 8
homogeneous as possible and which are from a lot of material
in.]. Cut the specimens to be used for grab tests in the machine
of the type in question. The test specimens should then be
direction with the longer dimension parallel to the machine
randomly assigned in equal numbers to each laboratory for
direction and the specimens to be used for grab tests in the
testing.Theaverageresultsfromthetwolaboratoriesshouldbe
cross-machine direction with the longer dimension parallel to
compared using the appropriate Student’s t-test and an accept-
the cross-machine direction. Locate each group of specimens
able probability level chosen by the two parties before testing
along a diagonal line on the swatch so that each specimen will
is begun. If a bias is found, either its cause must be found and
contain different warp ends and filling picks. Draw a line 37
corrected or the purchaser and the manufacturer must agree to
mm [1.5 in.] from the edge of the specimen running its full
interpret future test results in the light of the known bias.
length. For woven and reinforced nonwoven fabrics, this line
5.3 Mostgeotextilefabricscanbetestedbythistestmethod.
must be accurately parallel to the lengthwise yarns in the
Some modification of clamping techniques may be necessary
specimen.
for a given fabric, depending upon its structure. Special
adaptation may be necessary with strong fabrics, or fabrics 8. Number of Specimens
made from glass fibers, to prevent them from slipping in the
8.1 Unless otherwise agreed upon as when provided in an
clamps or being damaged as a result of being gripped in the
applicable material specification, take a number of test speci-
clamps,suchascushioningtheclamporboardingthespecimen
mens per swatch in the laboratory sample such that the user
within the clamp.
may expect at the 95 % probability level that the test result is
5.4 This test method is applicable for testing fabrics either nomorethan5 %abovethetrueaverageforeachswatchinthe
dryorwet.Itmaybeusedwithconstant-rate-of-traverse(CRT) laboratory sample for each the machine and cross-machine
or constant-rate-of-extension (CRE) type tension machines. direction, respectively.
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D4632/D4632M − 08 (2013)
it may be sufficient in routine testing to expose the material to the standard
8.1.1 Reliable Estimate of v—When there is a reliable
atmosphere for testing for a reasonable period of time before the
estimate of v based upon extensive past records for similar
specimens are tested.Atime of at least 24 h has been found acceptable in
materials tested in the user’s laboratory as directed in the
most cases. However, certain fibers may exhibit slow moisture equaliza-
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