ASTM D4632/D4632M-15a(2023)
(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 method 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 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, health, and environmental 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.
General Information
Relations
Standards Content (Sample)
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.
Designation: D4632/D4632M − 15a (Reapproved 2023)
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.
1. Scope 2. Referenced Documents
1.1 This test method is an index test which provides a 2.1 ASTM Standards:
procedure for determining the breaking load (grab strength) D76/D76M Specification for Tensile Testing Machines for
and elongation (grab elongation) of geotextiles using the grab Textiles
method. This test method is not suitable for knitted fabrics and D123 Terminology Relating to Textiles
alternate test methods should be used. While useful for quality D1776/D1776M Practice for Conditioning and Testing Tex-
control and acceptance testing for a specific fabric structure, tiles
the results can only be used comparatively between fabrics D2905 Practice for Statements on Number of Specimens for
with very similar structures because each different fabric Textiles (Withdrawn 2008)
structure performs in a unique and characteristic manner in this D4354 Practice for Sampling of Geosynthetics and Rolled
test. The grab test method does not provide all the information Erosion Control Products (RECPs) for Testing
needed for all design applications and other test methods D4439 Terminology for Geosynthetics
should be used. E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1.2 Procedures for measuring the breaking load and elon-
E691 Practice for Conducting an Interlaboratory Study to
gation by the grab method in both the dry and wet state are
Determine the Precision of a Test Method
included; however, testing is normally done in the dry condi-
tion unless specified otherwise in an agreement or specifica-
3. Terminology
tion.
3.1 Definitions:
1.3 The values stated in either SI units or inch-pound units
3.1.1 atmosphere for testing geotextiles, n—air maintained
are to be regarded separately as standard. The values stated in
at a relative humidity of 65 6 5 % relative humidity and
each system are not necessarily exact equivalents; therefore, to
temperature of 21 6 2 °C [70 6 4 °F].
ensure conformance with the standard, each system shall be
3.1.2 breaking load, n—the maximum force applied to a
used independently of the other, and values from the two
specimen in a tensile test carried to rupture.
systems shall not be combined.
3.1.3 cross-machine direction, n—the direction in the plane
1.4 This standard does not purport to address all of the
of the fabric perpendicular to the direction of manufacture.
safety concerns, if any, associated with its use. It is the
3.1.4 elongation at break, n—the elongation corresponding
responsibility of the user of this standard to establish appro-
to the breaking load, that is, the maximum load.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3.1.5 geotextile, n—any permeable textile material used
1.5 This international standard was developed in accor-
with foundation, soil, rock, earth, or any other geotechnical
dance with internationally recognized principles on standard-
material, as an integral part of a man-made product, structure,
ization established in the Decision on Principles for the
or system.
Development of International Standards, Guides and Recom-
3.1.6 grab test, n—in fabric testing, a tension test in which
mendations issued by the World Trade Organization Technical
only a part of the width of the specimen is gripped in the
Barriers to Trade (TBT) Committee.
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, 2023. Published May 2023. Originally the ASTM website.
approved in 1991. Last previous edition approved in 2015 as D4632/D4632M – 15a. The last approved version of this historical standard is referenced on
DOI: 10.1520/D4632_D4632M-15AR23. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4632/D4632M − 15a (2023)
3.1.6.1 Discussion—For example, if the specimen width is or constant-rate-of-extension (CRE) type tension machines.
101.6 mm [4 in.] and the width of the jaw faces However, there may be no overall correlation between the
25.4 mm [1 in.], the specimen is gripped centrally in the results obtained with the CRT machine and the CRE machine.
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
interfaced computers.
50.8 mm [1 by 2 in.], with the longer dimension parallel to the
direction of application of the load. The other jaw face of each
5. Significance and Use
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
is no simple relationship between grab tests and strip tests since
7.1 Division into Lots and Lot Samples—Divide the material
the amount of fabric assistance depends on the construction of
into lots and take a lot sample as directed in Practice D4354.
the fabric. It is useful as a quality control or acceptance test.
Rolls of fabric are the primary sampling unit.
5.2 The procedure in Test Method D4632/D4632M for the
7.2 Laboratory Sample—Take for the laboratory sample a
determination of grab strength of geotextiles may be used for
swatch extending the width of the fabric and approximately
acceptance testing of commercial shipments, but caution is
1 m [39.37 in.] along the selvage from each roll in the lot
advised since information about between-laboratory precision
sample. The swatch may be taken from the end portion of a roll
is incomplete. Comparative tests as directed in 5.2.1 are
provided there is no evidence that it is distorted or different
advisable.
from other portions of the roll. In cases of dispute, take a
5.2.1 In case of a dispute arising from differences in
swatch that will exclude fabric from the outer wrap of the roll
reported test results when using the procedures in Test Method
or the inner wrap around the core.
D4632/D4632M for acceptance testing of commercial
7.3 Test Specimens—Cut the number of specimens from
shipments, the purchaser and the manufacturer should conduct
each swatch in the laboratory sample determined as directed in
comparative tests to determine if there is a statistical bias
Section 8. Take no specimens nearer the selvage of fabric edge
between their laboratories. Competent statistical assistance is
than ⁄20 of the fabric width or 150 mm [6 in.], whichever is the
recommended for the investigation of bias. As a minimum, the
smaller. Cut rectangular specimens 101.6 by
two parties should take a group of test specimens that are as
203.2 mm [4 by 8 in.]. Cut the specimens to be used for grab
homogeneous as possible and which are from a lot of material
tests in the machine direction with the longer dimension
of the type in question. The test specimens should then be
parallel to the machine direction and the specimens to be used
randomly assigned in equal numbers to each laboratory for
for grab tests in the cross-machine direction with the longer
testing. The average results from the two laboratories should be
dimension parallel to the cross-machine direction. Locate each
compared using the appropriate Student’s t-test and an accept-
group of specimens along a diagonal line on the swatch so that
able probability level chosen by the two parties before testing
each specimen will contain different warp ends and filling
is begun. If a bias is found, either its cause must be found and
picks. Draw a line 37 mm [1.5 in.] from the edge of the
corrected or the purchaser and the manufacturer must agree to
specimen running its full length. For woven and reinforced
interpret future test results in the light of the known bias.
nonwoven fabrics, this line must be accurately parallel to the
5.3 Most geotextile fabrics can be tested by this test method.
lengthwise yarns in the specimen.
Some modification of clamping techniques may be necessary
for a given fabric, depending upon its structure. Special 8. Number of Specimens
adaptation may be necessary with strong fabrics, or fabrics
8.1 Unless otherwise agreed upon as when provided in an
made from glass fibers, to prevent them from slipping in the
applicable material specification, take a number of test speci-
clamps or being damaged as a result of being gripped in the
mens per swatch in the laboratory sample such that the user
clamps, such as cushioning the clamp or boarding the specimen
may expect at the 95 % probability level that the test result is
within the clamp.
no more than 5 % above the true average for each swatch in the
5.4 This test method is applicable for testing fabrics either laboratory sample for each the machine and cross-machine
dry or wet. It may be used with constant-rate-of-traverse (CRT) direction, respectively.
D4632/D4632M − 15a (2023)
reached. While such a procedure cannot be accepted in cases of dispute,
8.1.1 Reliable Estimate of v—When there is a reliable
it may be sufficient in routine testing to expose the material to the standard
estimate of v based upon extensive past records for similar
atmosphere for testing for a reasonable period of time before the
materials tested in the user’s laboratory as directed in the
specimens are tested. A time of at least 24 h has been found acceptable in
method, calculate the required number of specimens using Eq
most cases. However, certain fibers may exhibit slow moisture equaliza-
1, as follows:
tion rates from the “as received” wet side. When this is known, a
preconditioning cycle, as described in Practice D1776/D1776M, may be
n 5 tv/A (1)
~ !
agreed upon between contractual parties.
where:
9.2 Specimens to be tested in the wet condition shall be
n = number of test specimens (rounded upward to a whole immersed in water maintained at a temperature of 21 6 2 °C
number), [70 6 4 °F]. The time of immersion must be sufficient to
v = reliable estimate of the coefficient of variation of indi- wet-out the specimens thoroughly, as indicated by no signifi-
vidual observations on similar materials in the user’s cant change in strength or elongation following a longer period
laboratory under conditions of single-operator of immersion, and at least 2 min. To obtain thorough wetting,
precision, %, it may be necessary or advisable to add not more than 0.05 %
t = the value of Student’s t for one-sided limits (see Table
of a nonionic neutral wetting agent to the water.
1), a 95 % probability level, and the degrees of freedom
10. Procedure
associated with the estimate of v, and
A = 5.0 % of the average, the value of the allowable 10.1 Test the conditioned specimens in the standard atmo-
variation.
sphere for testing in accordance with Section 9.
8.1.2 No Reliable Estimate of v—When there is no reliable
10.2 Set the distance between the clamps at the start of the
estimate of v for the user’s laboratory, Eq 1 should not be used
test at 75 6 1 mm [3 6 0.05 in.]. Select the load range of the
directly. Instead, specify the fixed number of ten specimens for
testing machine such that the maximum load occurs between
the machine direction tests and ten specimens for the cross- 10 and 90 % of full-scale load. Set the machine to operate at a
machine direction tests. The number of specimens is calculated
speed of 300 6 10 mm/min [12 6 0.5 in./min].
using v = 9.5 % of the average for both machine direction and
10.3 Secure the specimen in the clamps of the testing
cross-machine direction. These values for v are somewhat
machine, taking care that the long dimension is as nearly as
larger than usually found in practice. When a reliable estimate
possible parallel to the direction of application of the load. Be
of v for the user’s laboratory becomes available, Eq 1 will
sure that the tension in the specimen is uniform across the
usually require fewer than the fixed number of specimens.
clamped width. Insert the specimen in the clamps so that
approximately the same length of fabric extends beyond the
9. Conditioning
jaw at each end. Locate the jaws centrally in the widthwise
9.1 Bring the specimens to moisture equilibrium in the
direction by having the line which was drawn 37 mm [1.5 in.]
atmosphere for testing geotextiles. Equilibrium is considered to
from the edge of the specimen run adjacent to the side of the
have been reached when the increase in mass of the specimen
upper and lower front jaws which are nearest this edge. This
in successive weighings made at intervals of not less than 2 h
ensures that the same lengthwise yarns are gripped in both
does not exceed 0.1
...
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