ASTM D8490-23a

Standard Test Method for Determining the Pore Size Characteristics of Geotextiles Using an Optical Method

SIGNIFICANCE AND USE
5.1 The significant opening size of geotextiles is usually determined using Test Method D4751, which involves sieving calibrated beads through specimens of the geotextile being evaluated. However, Test Method D4751 includes many risks of errors due to static electricity, precision of the glass beads, among other issues.5 This risk of error is even higher with knitted geotextiles which exhibit a very low tensile modulus. This test method is proposed as an alternate to Test Method D4751 using a nondestructive technique, where the stress conditions are controlled without manipulation of the specimen.  
5.2 This test method has been found to provide representative results for products exhibiting a planar structure, such as two-dimensional knits.  
5.3 In case of a dispute arising from differences in reported test results when using ASTM D4751 Method A and this method, ASTM D4751 Method A shall be considered the referee method. However, data obtained using ASTM D4751 Method A should be reviewed considering the high risk of human error associated with the control of the stress condition of the geotextile.  
5.4 Equivalency with the other pore opening size determined using other standards (for example, ISO 12956 and CGSB 148.1 No. 10) can also be considered using adequate correlations with test results obtained with these standards.
SCOPE
1.1 This test method covers the determination of the pore size characteristics of geotextiles using an optical method and image analysis.  
1.2 This method has been developed for determination of the Image Opening Size (IOS) of knitted geotextiles by image analysis. Other properties may be obtained based on the pore size distribution.  
1.3 The applicability of this test method must be assessed on a product-by-product basis, as it requires light to pass through its thickness to provide a useful observation. As a general rule, the tested product must be thin. Example of products which cannot be tested using this test method is thick needle-punched nonwoven and woven with a complex three-dimensional structure.  
1.4 This test method shows values in both SI units and inch-pound units. SI units is the technically correct name for the system of metric units known as the International System of Units. Inch-pound units is the technically correct name for the customary units used in the United States. The values in inch-pound units are provided for information only.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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

• Status: Published
• Publication Date: 14-Jun-2023
• ICS: 59.080.70 - Geotextiles
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.03 - Permeability and Filtration

Relations

• Refers: ASTM D4354-12(2020) - Standard Practice for Sampling of Geosynthetics and Rolled Erosion Control Products (RECPs) for Testing
• Effective Date: 01-May-2020
• Refers: ASTM D4751-20 - Standard Test Methods for Determining Apparent Opening Size of a Geotextile
• Effective Date: 01-Jan-2020

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: D8490 − 23a
Standard Test Method for
Determining the Pore Size Characteristics of Geotextiles
1
Using an Optical Method
This standard is issued under the fixed designation D8490; 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 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 This test method covers the determination of the pore
D123 Terminology Relating to Textiles
size characteristics of geotextiles using an optical method and
D4354 Practice for Sampling of Geosynthetics and Rolled
image analysis.
Erosion Control Products (RECPs) for Testing
1.2 This method has been developed for determination of
D4439 Terminology for Geosynthetics
the Image Opening Size (IOS) of knitted geotextiles by image
D4751 Test Methods for Determining Apparent Opening
analysis. Other properties may be obtained based on the pore
Size of a Geotextile
size distribution.
E11 Specification for Woven Wire Test Sieve Cloth and Test
Sieves
1.3 The applicability of this test method must be assessed on
2.2 Other Standards:
a product-by-product basis, as it requires light to pass through
ISO 12956 Geotextiles and Geotextile-Related Products—
its thickness to provide a useful observation. As a general rule,
3
Determination of the Characteristic Opening Size
the tested product must be thin. Example of products which
CGSB 148.1 No. 10 Methods of Testing Geosynthetics
cannot be tested using this test method is thick needle-punched
4
Geotextiles—Filtration Opening Size
nonwoven and woven with a complex three-dimensional struc-
ture. 3. Terminology
3.1 Definitions—For definitions of other textile terms used
1.4 This test method shows values in both SI units and
in this test method, refer to Terminology D123. For definitions
inch-pound units. SI units is the technically correct name for
of other terms relating to geosynthetics used in this test
the system of metric units known as the International System of
method, refer to Terminology D4439.
Units. Inch-pound units is the technically correct name for the
customary units used in the United States. The values in
3.2 Definitions of Terms Specific to This Standard:
inch-pound units are provided for information only. 3.2.1 circular knit, n—a structure produced by interlooping
one or more ends of yarn or comparable material in a
1.5 This standard does not purport to address all of the
continuously circular orientation around the fabric.
safety concerns, if any, associated with its use. It is the
3.2.2 ellipse diameter, n—measured from the “best-fit” el-
responsibility of the user of this standard to establish appro-
lipse fitting inside a given opening.
priate safety, health, and environmental practices and deter-
3.2.2.1 Discussion—The minimum and maximum ellipse
mine the applicability of regulatory limitations prior to use.
diameter are the smallest and largest diameter of the ellipse
1.6 This international standard was developed in accor-
fitting the inside of an opening when varying the axis of the
dance with internationally recognized principles on standard-
ellipse in the plane of observation (Fig. 1).
ization established in the Decision on Principles for the
3.2.3 Feret diameter, n—distance between two parallel lines
Development of International Standards, Guides and Recom-
tangent to the silhouette of the opening.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
1
This test method is under the jurisdiction of ASTM Committee D35 on the ASTM website.
3
Geosynthetics and is the direct responsibility of Subcommittee D35.03 on Perme- Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
ability and Filtration. 4th Floor, New York, NY 10036, http://www.ansi.org.
4
Current edition approved June 15, 2023. Published June 2023. Originally Available from Canadian General Standards Board (CGSB), 11 Laurier St.,
approved in 2023. Last previous edition approved in 2023 as D8490 – 23. DOI: Phase III, Place du Portage, Gatineau, Quebec K1A 0S5, Canada, http://www.tpsgc-
10.1520/D8490-23A. pwgsc.gc.ca/ongc-cgsb.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D8490 − 23 D8490 − 23a
Standard Test Method for
Determining the OpeningPore Size Characteristics of
1
Circular Knit Geotextiles Using an Optical Method
This standard is issued under the fixed designation D8490; 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
1.1 This test method covers the determination of the Image Opening Size (IOS) of a geotextile by pore size characteristics of
geotextiles using an optical method and image analysis.
1.2 This method has been developed for determination of the Image Opening Size (IOS) of knitted geotextiles by image analysis.
Other properties may be obtained based on the pore size distribution.
1.3 The applicability of this test method must be assessed on a product-by-product basis, as it requires light to pass through its
thickness to provide a useful observation. As a general rule, the tested product must be thin. Example of products which cannot
be tested using this test method is thick needle-punched nonwoven and woven with a complex three-dimensional structure.
1.4 This test method shows values in both SI units and inch-pound units. SI units is the technically correct name for the system
of metric units known as the International System of Units. Inch-pound units is the technically correct name for the customary units
used in the United States. The values in inch-pound units are provided for information only.
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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D123 Terminology Relating to Textiles
D4354 Practice for Sampling of Geosynthetics and Rolled Erosion Control Products (RECPs) for Testing
D4439 Terminology for Geosynthetics
D4751 Test Methods for Determining Apparent Opening Size of a Geotextile
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
1
This test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.03 on Permeability and
Filtration.
Current edition approved Feb. 1, 2023June 15, 2023. Published February 2023June 2023. Originally approved in 2023. Last previous edition approved in 2023 as
D8490 – 23. DOI: 10.1520/D8490-23.10.1520/D8490-23A.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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
1

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D8490 − 23a
2.2 Other Standards:
3
ISO 12956 Geotextiles and Geotextile-Related Products—Determination of the Characteristic Opening Size
4
CGSB 148.1 No. 10 Methods of Testing Geosynthetics Geotextiles—Filtration Opening Size
3. Terminology
3.1 Definitions—For definitions of other textile terms used in this test method, refer to Terminology D123. For definitions of other
terms relating to geosynthetics used in this test method, refer to Terminology D4439.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 circular knit, n—a structure produced by interlooping one or more ends of yarn or comparable material in a continuously
circular orientation around the fabric.
3.2.2 ellipse diameter, n—measured from the “best-fit” ellipse fitting inside a given opening.
3.2.2.1 Discussion—
The minimum and maximum ellipse diameter are the smallest and largest diameter of the ellipse fitting the inside of an opening
when varying the axis of the ellipse in the plane of observation.observation (Fig. 1).
3.2.3 Feret diameter, n—distance between two parallel lines tangent to the silhouette of the opening.
3.2.3.1 Discussion—
...