ASTM D8212-24e1

• Abstract:

  SIGNIFICANCE AND USE; 4.1 The determination of the tensile force-elongation values of geogrids provides index property values. This standard practice shall be used for the determination of radial properties, judgment of conformity of product manufactured, and acceptance of commercial shipments of geogrids. ; 4.2 The standard strain at which this practice is applied is 2 %, as this has been established and accepted over the years as the lowest strain at which consistent measurement of the properties of geogrids can be achieved. However, if a customer or specifier requires calculation at a lower strain, this can be done provided the higher standard deviation this can give is accepted. ; 4.3 In cases of dispute arising from differences in reported results when using this standard practice for acceptance testing of commercial shipments, the purchaser and supplier should conduct comparative tests and calculations 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 results in light of the known bias. ; 4.4 This standard practice is applicable to all geogrids with two or three sets of ribs in which variation of tensile properties between different sets of parallel ribs is 20 % or less. For multiple-layered geogrids, it should be applied to each layer individually and the results for all layers summed in each radial di...; SCOPE; 1.1 This practice presents a method for determining in-air index values (see Note 1) of the radial load and radial stiffness at low strain in each symmetric direction of a balanced geogrid (see Note 2) subjected to 360° radial strain. This determination is based on tensile test results from testing in accordance with Test Method D6637/D6637M and an analysis of the radial force balance in each symmetric direction across a circle of geogrid that is assumed to be strained uniformly in all radial directions to a low strain level. ; 1.2 Symmetric directions relative to the machine direction: ; 1.2.1 For geogrids with square or rectangular apertures: 0°, 45°, 90°, 135°. ; 1.2.2 For geogrids with triangular apertures: 0°, 30°, 60°, 90°, 120°, 150°. ; Note 1: These index properties are not to be used for design or performance purposes. ; Note 2: A balanced geogrid is one in which the manufacturer’s specification indicates that variation of tensile properties between different sets of parallel ribs is 20 % or less. ; 1.3 This practice will facilitate comparisons of the radial tensile properties of different balanced geogrids and judgment of conformity of product manufactured and acceptance of commercial shipments of geogrids by standardizing the data used and the method by which the calculations are performed. ; 1.4 This standard practice is restricted in application to geogrids with two sets of parallel ribs arranged at nominally 90° to each other or three sets of parallel ribs arranged at nominally 60° to each other with one set lying in the cross-machine direction. ; 1.5 Further, this practice is restricted to 20 % variation in the specified unit tensile properties of the different sets of ribs in a geogrid in order to enable the development of the mathematics that use these properties of each set of ribs in the geogrid. This generates index values for the unit tensile properties in the nominal directions as outlined in ...

• Status: Published
• Publication Date: 31-Jan-2024
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.01 - Mechanical Properties

• Replaces: ASTM D8212-24 - Standard Practice for Determination of the Radial Tensile Properties of Geogrids Under Low Radial Strain
• Effective Date: 01-Feb-2024

Overview

ASTM D8212-24e1 is the Standard Practice for Determination of the Radial Tensile Properties of Geogrids Under Low Radial Strain. Developed by ASTM International, this standard establishes a method for determining the in-air index values of radial load and radial stiffness at low strain in each symmetric direction of balanced geogrids. This enables consistent testing for product conformity and quality control in the geosynthetics industry. The standard is specifically tailored for geogrids with intersecting ribs, ensuring that variations in tensile properties between rib sets are minimal (within 20%).

Key Topics

• Radial tensile properties: The standard focuses on evaluating radial load and stiffness at low strain, typically 2%, for balanced geogrids. This measurement is essential for quality assurance but is not intended for direct use in design or performance applications.
• Applicability: The practice covers geogrids with two sets of parallel ribs (typically at 90°) or three sets (at 60°), where the variation in tensile properties between rib sets does not exceed 20%. It is not suitable for uniaxial geogrids.
• Symmetric directions: Testing is conducted along predefined angles based on the geogrid aperture shape:
  • Square/rectangular apertures: 0°, 45°, 90°, 135°
  • Triangular apertures: 0°, 30°, 60°, 90°, 120°, 150°
• Consistent measurement strain: The default strain for property measurement is set at 2%, ensuring accuracy and repeatability across laboratories. If lower strain is required, it is allowed with the understanding that measurement variance may increase.
• Resolution of laboratory bias: In the event of discrepancies between test results from different laboratories, the standard outlines statistical comparison methods (e.g., Student’s t-test) to assess potential bias and prescribes steps for reconciliation.

Applications

• Product conformity: Manufacturers and suppliers use this standard to verify that geogrids meet specified quality benchmarks before acceptance of commercial shipments.
• Quality assurance and control: Consistent testing methodologies across laboratories facilitate straightforward comparison and evaluation between different geogrid products.
• Specification compliance: Purchasers can reference ASTM D8212-24e1 to ensure that materials supplied align with project requirements and industry best practices.
• Material comparison: Standardized radial tensile property data aids in selecting the appropriate geogrid type for specific geotechnical engineering applications.
• Multi-layer geogrids: The practice includes guidelines for evaluating each geogrid layer individually when dealing with composite or layered products.

Related Standards

• ASTM D6637/D6637M: Test Method for Determining Tensile Properties of Geogrids by the Single or Multi-Rib Tensile Method. This test method is fundamental to the procedures described in ASTM D8212-24e1.
• ASTM D4439: Terminology for Geosynthetics. Provides definitions and terms necessary for understanding and implementing geosynthetic-related standards.
• International standardization principles: ASTM D8212-24e1 aligns with the World Trade Organization Technical Barriers to Trade (TBT) Committee guidelines, promoting global acceptance and harmonization.

Practical Value

ASTM D8212-24e1 delivers a structured and reliable approach for assessing the index tensile properties of geogrids under controlled conditions. Utilizing this standard enhances uniformity in material evaluation, ensures reliable procurement, supports dispute resolution, and underpins the integrity of geosynthetic supply chains. The focus on low-strain, radial properties specifically addresses the needs of manufacturers, specifiers, and project managers engaged in geotechnical or civil engineering projects relying on geogrid reinforcement.

Keywords: geogrid, radial tensile properties, ASTM D8212, geosynthetics, radial load, radial stiffness, low strain, index testing, material conformity, quality control, testing standard.

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.
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Designation: D8212 − 24
Standard Practice for
Determination of the Radial Tensile Properties of Geogrids
Under Low Radial Strain
This standard is issued under the fixed designation D8212; 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.
ε NOTE—The title of Appendix X1 was editorially corrected in March 2024.
1. Scope in a geogrid in order to enable the development of the
mathematics that use these properties of each set of ribs in the
1.1 This practice presents a method for determining in-air
geogrid. This generates index values for the unit tensile
index values (see Note 1) of the radial load and radial stiffness
properties in the nominal directions as outlined in 1.2.1 and
at low strain in each symmetric direction of a balanced geogrid
1.2.2 of a geogrid that is under 360° radial strain at any
(see Note 2) subjected to 360° radial strain. This determination
designated strain level. A 2 % strain level is set as the default
is based on tensile test results from testing in accordance with
strain of choice as it has been found that this is the lowest strain
Test Method D6637/D6637M and an analysis of the radial
level at which most test laboratories can achieve consistent
force balance in each symmetric direction across a circle of
low-strain tensile test results on geogrids.
geogrid that is assumed to be strained uniformly in all radial
directions to a low strain level.
1.6 Calculations in accordance with this practice determine
the radial component of the unit tensions generated in the
1.2 Symmetric directions relative to the machine direction:
geogrid. Differences in the unit tensions of different rib sets
1.2.1 For geogrids with square or rectangular apertures: 0°,
will also give tangential components of force. With a difference
45°, 90°, 135°.
in tension between rib sets restricted to 20 % or less, it has been
1.2.2 For geogrids with triangular apertures: 0°, 30°, 60°,
found that these tangential components will be approximately
90°, 120°, 150°.
10 % or less of the values of the radial components. Therefore,
NOTE 1—These index properties are not to be used for design or
the resultant of the radial and tangential component in any
performance purposes.
symmetric direction will be less than 0.5 % greater than the
NOTE 2—A balanced geogrid is one in which the manufacturer’s
radial component. As this is less than the variation normally
specification indicates that variation of tensile properties between different
sets of parallel ribs is 20 % or less. found in tensile testing of a set of rib or wide-width specimens,
it does not detract from the calculated radial tensions being
1.3 This practice will facilitate comparisons of the radial
valid index properties of the geogrid.
tensile properties of different balanced geogrids and judgment
of conformity of product manufactured and acceptance of
1.7 This practice is not applicable to uniaxial geogrids.
commercial shipments of geogrids by standardizing the data
1.8 The values stated in SI units are to be regarded as the
used and the method by which the calculations are performed.
standard. The values given in parentheses are for information
1.4 This standard practice is restricted in application to
only.
geogrids with two sets of parallel ribs arranged at nominally
1.9 This standard does not purport to address all of the
90° to each other or three sets of parallel ribs arranged at
safety concerns, if any, associated with its use. It is the
nominally 60° to each other with one set lying in the cross-
responsibility of the user of this standard to establish appro-
machine direction.
priate safety, health, and environmental practices and deter-
1.5 Further, this practice is restricted to 20 % variation in
mine the applicability of regulatory limitations prior to use.
the specified unit tensile properties of the different sets of ribs
1.10 This international standard was developed in accor-
dance with internationally recognized principles on standard-
This practice is under the jurisdiction of ASTM Committee D35 on Geosyn-
ization established in the Decision on Principles for the
thetics and is the direct responsibility of Subcommittee D35.01 on Mechanical
Development of International Standards, Guides and Recom-
Properties.
mendations issued by the World Trade Organization Technical
Current edition approved Feb. 1, 2024. Published February 2024. DOI: 10.1520/
D8212-24E01. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D8212 − 24
2. Referenced Documents 5. Procedure
2.1 ASTM Standards: 5.1 For geogrids with square or rectangular apertures:
D4439 Terminology for Geosynthetics
5.1.1 Obtain the average wide-width unit tensile load in
D6637/D6637M Test Method for Determining Tensile Prop-
kN/m (lbf/ft) at 2 % strain and any other strain level designated
erties of Geogrids by the Single or Multi-Rib Tensile
by the designer or customer for the machine direction (MD)
Method
and cross-machine direction (CMD) ribs in the geogrid under
consideration from tests in accordance with Test Method
3. Terminology
D6637/D6637M, Method B.
3.1 Definitions:
5.1.2 Calculate the radial loads in the geogrid at 2 % strain
3.1.1 radial—of or arranged like rays or the radii of a circle,
and any other designated strain in each symmetric direction
diverging in lines from a common center. around 360° (MD = 0°) using the following formulae:
5.1.2.1 Rib directions (0° and 90°):
3.1.2 unit load—the load per unit width of geogrid ex-
pressed as kN/m (lbf/ft).
L or L 5 wide width unit tensile load in MD or CMD (1)
0 90
3.2 Other definitions required for the understanding of this
5.1.2.2 Between rib directions (45° and 135°):
standard practice are available in Terminology D4439.
L or L 5 L *cos45 1 L *cos45 *cos45 5 L 1 L ⁄ 2 (2)
~ ! ~ !
45 135 0 90 0 90
4. Significance and Use
where:
4.1 The determination of the tensile force-elongation values
L = the radial load in a designated direction ϴ.
Θ
of geogrids provides index property values. This standard
5.2 For geogrids with triangular apertures:
practice shall be used for the determination of radial properties,
5.2.1 Obtain the average single rib tensile load in kN (lbf) at
judgment of conformity of product manufactured, and accep-
2 % strain and any other strain level designated by the designer
tance of commercial shipments of geogrids.
or customer for each set of ribs in the geogrid under consid-
4.2 The standard strain at which this practice is applied is
eration from tests in accordance with Method A of Test Method
2 %, as this has been established and accepted over the years as
D6637/D6637M, modified to include load-strain recording.
the lowest strain at which consistent measurement of the
5.2.2 Obtain the number of ribs per meter (ribs per foot) for
properties of geogrids can be achieved. However, if a customer
each set of ribs in the geogrid under consideration (see Note 3).
or specifier requires calculation at a lower strain, this can be
5.2.3 Calculate the load per unit width at 2 % strain and at
done provided the higher standard deviation this can give is
any designated strain for each set of ribs using the following
accepted.
formula:
4.3 In cases of dispute arising from differences in reported
L 5 F *N kN/m ~lbf/ft! (3)
x x t
results when using this standard practice for acceptance testing
where:
of commercial shipments, the purchaser and supplier should
conduct c
...