ASTM D6637-01(2009)
(Test Method)Standard Test Method for Determining Tensile Properties of Geogrids by the Single or Multi-Rib Tensile Method
Standard Test Method for Determining Tensile Properties of Geogrids by the Single or Multi-Rib Tensile Method
SIGNIFICANCE AND USE
The determination of the tensile force-elongation values of geogrids provides index property values. This test method shall be used for quality control and acceptance testing of commercial shipments of geogrids.
In cases of dispute arising from differences in reported test results when using this test method for acceptance testing of commercial shipments, the purchaser and supplier 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 which 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 student's t-test for unpaired data and an acceptable probability level chosen by the two parties before the testing began. If a bias is found, either its cause must be found and corrected or the purchaser and supplier must agree to interpret future test results in light of the known bias.
All geogrids can be tested by any of these methods. Some modification of techniques may be necessary for a given geogrid depending upon its physical make-up. Special adaptations may be necessary with strong geogrids, multiple layered geogrids, or geogrids that tend to slip in the clamps or those which tend to be damaged by the clamps.
SCOPE
1.1 This test method covers the determination of the tensile strength properties of geogrids by subjecting strips of varying width to tensile loading.
1.2 Three alternative procedures are provided to determine the tensile strength, as follows:
1.2.1 Method A—Testing a single geogrid rib in tension (N or lbf).
1.2.2 Method B—Testing multiple geogrid ribs in tension (kN/m or lbf/ft).
1.2.3 Method C—Testing multiple layers of multiple geogrid ribs in tension (kN/m or lbf/ft)
1.3 This test method is intended for quality control and conformance testing of geogrids.
1.4 The values stated in SI units are to be regarded as the standard. The inch-pound values stated in parentheses are provided for information only.
1.5 This standard may involve hazardous materials, operations, and equipment. 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:D6637–01 (Reapproved 2009)
Standard Test Method for
Determining Tensile Properties of Geogrids by the Single or
Multi-Rib Tensile Method
This standard is issued under the fixed designation D6637; 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 D5262 Test Method for Evaluating the Unconfined Tension
Creep and Creep Rupture Behavior of Geosynthetics
1.1 This test method covers the determination of the tensile
strength properties of geogrids by subjecting strips of varying
3. Terminology
width to tensile loading.
3.1 Definitions:
1.2 Three alternative procedures are provided to determine
3.1.1 atmosphere for testing geosynthetics, n—air main-
the tensile strength, as follows:
tained at a relative humidity of 50 to 70 % and a temperature
1.2.1 Method A—Testing a single geogrid rib in tension (N
of 21 6 2°C (70 6 4°F).
or lbf).
3.1.2 breaking force, (F), n—the force at failure.
1.2.2 Method B—Testing multiple geogrid ribs in tension
3.1.3 corresponding force, n—synonym for force at speci-
(kN/m or lbf/ft).
fied elongation.
1.2.3 Method C—Testing multiple layers of multiple geo-
3.1.4 force at specified elongation, FASE, n—a force asso-
grid ribs in tension (kN/m or lbf/ft)
ciated with a specific elongation on the force-elongation curve.
1.3 This test method is intended for quality control and
(synonym for corresponding force.)
conformance testing of geogrids.
3.1.5 force-elongation curve, n—in a tensile test, a graphi-
1.4 The values stated in SI units are to be regarded as the
cal representation of the relationship between the magnitude of
standard. The inch-pound values stated in parentheses are
an externally applied force and the change in length of the
provided for information only.
specimen in the direction of the applied force. (synonym for
1.5 This standard may involve hazardous materials, opera-
stress-strain curve.)
tions, and equipment. This standard does not purport to
3.1.6 geogrid, n—a geosynthetic formed by a regular net-
address all of the safety concerns, if any, associated with its
work of integrally connected elements with aperetures greater
use. It is the responsibility of the user of this standard to
than 6.35 mm ( ⁄4 inch) to allow interlocking with surrounding
establish appropriate safety and health practices and deter-
soil, rock, earth, and other surrounding materials to primarily
mine the applicability of regulatory limitations prior to use.
function as reinforcement. (D5262)
2. Referenced Documents 3.1.7 integral, adj—in geosynthetics, forming a necessary
2 part of the whole; a constituent.
2.1 ASTM Standards:
3.1.8 geosynthetic, n—a product manufactured from poly-
D76 Specification for Tensile Testing Machines for Textiles
meric material used with soil, rock, earth, or other geotechnical
D123 Terminology Relating to Textiles
engineering related material as an integral part of a man made
D1909 StandardTable of Commercial Moisture Regains for
project, structure, or system.
Textile Fibers
3.1.9 index test, n—a test procedure which may contain
D4354 Practice for Sampling of Geosynthetics for Testing
known bias, but which may be used to establish an order for a
D4439 Terminology for Geosynthetics
set of specimens with respect to the property of interest.
3.1.10 junction, n—the point where geogrid ribs are inter-
This test method is under the jurisdiction of ASTM Committee D35 on
connected to provide structure and dimensional stability.
Geosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-
3.1.11 rib , n—for geogrids, the continuous elements of a
cal Properties.
geogrid which are either in the machine or cross-machine
CurrenteditionapprovedJune1,2009.PublishedJuly2009.Originallyapproved
in 2001. Last previous edition approved in 2001 as D6637 – 01. DOI: 10.1520/
direction as manufactured.
D6637-01R09.
3.1.12 rupture, n—for geogrids, the breaking or tearing
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
apart of ribs.
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
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6637–01 (2009)
3.1.13 tensile, adj—capable of tensions, or relating to ten- cause must be found and corrected or the purchaser and
sion of a material. supplier must agree to interpret future test results in light of the
3.1.14 tensile strength, (a ), n—for geogrids the maximum known bias.
f
resistance to deformation developed for a specific material 5.3 All geogrids can be tested by any of these methods.
whensubjectedtotensionbyanexternalforce.Tensilestrength Some modification of techniques may be necessary for a given
of geogrids is the characteristic of a sample as distinct from a geogrid depending upon its physical make-up. Special adapta-
specimen and is expressed in force per unit width. tions may be necessary with strong geogrids, multiple layered
3.1.15 tensile test, n—for geosynthetics, a test in which a geogrids, or geogrids that tend to slip in the clamps or those
material is stretched uniaxially to determine the force- which tend to be damaged by the clamps.
elongation characteristics, the breaking force, or the breaking
elongation. 6. Apparatus
3.1.16 tension, n—the force that produces a specified elon-
6.1 Testing Clamps—The clamps shall be sufficiently wide
gation.
to grip the entire width of the specimen (as determined by the
3.2 For definitions of other terms used in this test method,
test method) and with appropriate clamping power to prevent
refer to Terminologies D123 and D4439.
slipping or crushing (damage). For a given product, the same
clamps shall be used in testing methods A, B, and C prior to
4. Summary of Test Method
making any comparison between results.
4.1 Method A—In this method, a single, representative rib
6.1.1 Size of Jaw Faces—Each clamp shall have jaw faces
specimen of a geogrid is clamped and placed under a tensile
measuring wider than the width of the specimen.
force using a constant rate of extension testing machine. The
6.2 Tensile Testing Machine—A testing machine of the
tensile force required to fail (rupture) the specimen is recorded.
constant rate of extension type as described in Specification
The ultimate single rib tensile strength (N or lbf) is then
D76 shall be used. The machine shall be equipped with a
determined based on the average of six single rib tensile tests.
device for recording the tensile force and the amount of
4.2 Method B—A relatively wide specimen is gripped
separation of the grips. Both of these measuring systems shall
across its entire width in the clamps of a constant rate of
be accurate to 6 1.0 % and, preferably, shall be external to the
extension type tensile testing machine operated at a prescribed
testing machine. The rate of separation shall be uniform and
rateofextension,applyingauniaxialloadtothespecimenuntil
capable of adjustment within the range of the test.
the specimen ruptures. Tensile strength (kN/m or lbf/ft),
6.3 Distilled Water and Nonionic Wetting Agent, shall be
elongation, and secant modulus of the test specimen can be
used for wet specimens only.
calculated from machine scales, dials, recording charts, or an
6.4 Extensometer—When required by the method, a device
interfaced computer.
capable of measuring the distance between two reference
4.3 Method C—A relatively wide, multiple layered speci-
points on the specimen without any damage to the specimen or
men is gripped across its entire width in the clamps of a
slippage, care being taken to ensure that the measurement
constantrateofextensiontypetensiletestingmachineoperated
represents the true movement of the reference points. Ex-
ataprescribedrateofextension,applyingauniaxialloadtothe
amples of extensometers include mechanical, optical, infrared
specimen until the specimen ruptures. Tensile strength (kN/m
or electrical devices.
or lbf/ft), elongation and secant modulus of the test specimen
can be calculated from machine scales, dials recording charts,
7. Sampling
or an interfaced computer.
7.1 Lot Sample—Divide the product into lots and take the
lot sample as directed in Practice D4354.
5. Significance and Use
7.2 Laboratory Sample—For the laboratory sample, take a
5.1 The determination of the tensile force-elongation values
full roll width swatch long enough in the machine direction
of geogrids provides index property values. This test method
from each roll in the lot sample to ensure that the requirements
shall be used for quality control and acceptance testing of
in 8.1 can be met. The sample may be taken from the end
commercial shipments of geogrids.
portion of a roll provided there is no evidence it is distorted or
5.2 In cases of dispute arising from differences in reported
different from other portions of the roll.
test results when using this test method for acceptance testing
of commercial shipments, the purchaser and supplier should
8. Test Specimen
conduct comparative tests to determine if there is a statistical
8.1 The specimens shall consist of three (3) junctions or 300
bias between their laboratories. Competent statistical assis-
mm in length (12 in.), in order to establish a minimum
tance is recommended for the investigation of bias. As a
specimen length in the direction of the test (either the machine
minimum, the two parties should take a group of test speci-
or cross-machine direction). All specimens should be free of
mens which are as homogeneous as possible and which are
surface defects, etc., not typical of the laboratory sample. Take
from a lot of material of the type in question. The test
no specimens nearer the selvage edge along the geogrid than
specimens should then be randomly assigned in equal numbers
⁄10 the width of the sample.
to each laboratory for testing.The average results from the two
laboratories should be compared using student’s t-test for
NOTE 1—If a comparison of one geogrid to another is to be made the
unpaireddataandanacceptableprobabilitylevelchosenbythe
length of each specimen shall be the same (as similar as possibly) and
twopartiesbeforethetestingbegan.Ifabiasisfound,eitherits agreed upon by all parties.
D6637–01 (2009)
8.2 Preparation:
8.2.1 Method A—Prepare each finished specimen, as shown
in Fig. 1, to contain one rib in the cross-test wide by at least
three junctions (two apertures) long in the direction of the
testing, with the length dimension being designated and accu-
rately cut parallel to the direction for which the tensile strength
is being measured.
8.2.2 Method B—Prepare each finished specimen, as shown
in Fig. 2, to be a minimum of 200 mm wide and contain five
FIG. 2 Specimen Dimensions for Methods B and C
ribs in the cross-test direction wide by at least three junctions
(two apertures) or 300 mm (12 in.) long in the direction of the
testing, with the length dimension being designated and accu-
where:
rately cut parallel to the direction for which the tensile strength
n = number of test specimens (rounded upward to a whole
is being measured.
number),
v = reliable estimate of the coefficient of variation of
8.2.3 Method C—Prepare each finished specimen, as shown
individual observations on similar materials in the
in Fig. 2, to be a minimum of 200 mm wide and contain five
user’s laboratory under conditions of single-operator
ribs in the cross-test direction wide by at least three junctions
precision, %,
(two apertures) or 300 mm (12 in.) long in the direction of the
t = the value of Student’s t for one-sided limits, a 95 %
testing, with the length dimension being designated and accu-
probability level, and the degrees of freedom associ-
rately cut parallel to the direction for which the tensile strength
ated with the estimate of v, and;
is being measured. This must be repeated for each layer of
A = 5.0 % of the average, the value of allowable variation.
geogrid included in the test.
8.3.3 No Reliable Estimate of v—When there is no reliable
8.2.4 Within test methodsA, B and C the outermost ribs are
estimate of v for the user’s laboratory, Eq 1 should not be used
cut prior to testing to prevent slippage from occurring within
directly. Instead, specify the fixed number of 5 specimens for
the clamps. For those cases where the outermost ribs are
the required direction. The number of specimens is calculated
severed, the test results shall be based on the unit of width
using v = 9.5 % of the average for the required direction. This
associated with the number of intact ribs.
value for v is somewhat larger than usually found in practice.
8.3 Number of Test Specimens:
When a reliable estimate of v for the user’s laboratory becomes
8.3.1 Unless otherwise agreed upon as when provided in an available, Eq 1 will usually require fewer than the fixed
applicable material specification, take a number of test speci- number of specimens.
mens per swatch in the laboratory sample such that the user
9. Conditioning
may expect at the 95 % probability level that the test result is
nomorethan5 %abovethetrueaverageforeachswatchinthe 9.1 Expose the specimens to the atmosphere for testing
laboratory sample for each required direction, see Note 2.
geosynthetics for a period long enough to allow the geogrid to
reach equilibrium within this standard atmosphere. Consider
NOTE 2—In some applications, it may be necessary to perform tensile
the specimen to be at moisture equilibrium when the change in
testsinboththemachineandthecross-machinedirections.Inallcases,the
mass of the specimen in successive weighings made at inter-
direction of the tensile test specimen(s) should be clearly noted.
vals of not less than 2 h does not exceed 0.1 % of the mass of
8.3.2 Reliable Estimate of v—When there is a reliable
the specimen. Consider the specimen to be at temperature
estimate of v based upon extensive past records for similar
equilibrium after1hof exposure to the atmosphere for testing
materials tested in the user’s laboratory as directed in the
geosynthetics.
method, calculate the required number of specimens using Eq
9.2 Specimens to be tested in the wet condition shall be
1, as follows:
immersed in water for a minimum of one hour, maintained at
2 a temperature of 21 6 2°C (70 6 4°F). The time of immersion
n 5 ~tv/A! (1)
must be sufficient to wet-out the specimens thoroughly, as
indicated by no significant change in strength or elongation
following a lon
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