ASTM D7466/D7466M-23

Standard Test Method for Measuring Asperity Height of Textured Geomembranes

SIGNIFICANCE AND USE
5.1 The asperity height is an index property used to quantify one of the physical attributes related to the surface roughness of textured geomembranes.  
5.2 This test method is applicable to all currently available textured geomembranes that are deployed as manufactured geomembrane sheets.
SCOPE
1.1 This test method covers a procedure to measure the asperity height of textured geomembranes.  
1.2 This test method does not provide for measurement of the spacing between the asperities nor of the complete profile of the textured surface.  
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

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 59.080.70 - Geotextiles
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.10 - Geomembranes

Relations

• Replaces: ASTM D7466/D7466M-10(2015)e1 - Standard Test Method for Measuring Asperity Height of Textured Geomembranes
• Effective Date: 01-Nov-2023
• Refers: ASTM D4439-24 - Standard Terminology for Geosynthetics
• Effective Date: 01-Feb-2024
• Refers: ASTM D4439-23b - Standard Terminology for Geosynthetics
• Effective Date: 15-Jul-2023
• Referred By: ASTM D6243/D6243M-20 - Standard Test Method for Determining the Internal and Interface Shear Strength of Geosynthetic Clay Liner by the Direct Shear Method
• Effective Date: 01-Nov-2023

Overview

ASTM D7466/D7466M-23: Standard Test Method for Measuring Asperity Height of Textured Geomembranes establishes a procedure to determine the asperity height, which is a key physical index used to quantify the surface roughness of textured geomembranes. The method provides consistent, repeatable measurement guidance for quality control, construction, and performance assessment of geomembrane materials.

Asperity height refers specifically to the protrusions or raised points on the textured surface of geomembranes, which influence properties like friction, interface stability, and overall effectiveness in geotechnical applications. This standard applies to all textured geomembrane sheets as manufactured, ensuring uniform evaluation across products and projects.

Key Topics

• Asperity Height Measurement: Defines a standardized laboratory method using a precision depth gauge, ensuring consistent readings across labs and projects.
• Scope Limitations: The method measures height only-not spacing or full profile-focusing specifically on the roughness index provided by the height of projections.
• Sample Preparation and Testing Conditions: Specifies sample dimensions, surface selection (Side A and Side B for double-sided products), and standardized laboratory humidity and temperature requirements.
• Reporting and Calculation: Details average value calculation from multiple measurements, as well as optional reporting of coefficient of variation.
• Precision and Bias: Includes repeatability and reproducibility guidelines, giving users confidence in the reliability and accuracy of their testing processes.

Applications

The asparity height test is critical for several practical applications within the geosynthetics and environmental engineering sectors:

• Quality Control: Manufacturers use this standard to ensure production consistency and material conformity of geomembranes prior to delivery or installation.
• Project Specifications: Project owners and engineers specify asperity height values to meet friction and stability requirements in landfill liners, mining containment, and environmental protection projects.
• Performance Verification: Contractors and inspectors use this test to confirm material suitability for as-installed geomembrane systems, reducing the risk of slippage or failure.
• Research and Development: Laboratories conducting comparative studies on geomembrane performance rely on standardized asperity height measurements for data integrity.

Textured geomembranes are widely used in landfill liners, mining leach pads, water containment structures, and environmental barriers. The asperity height directly impacts interface shear strength, making its proper measurement critical for safe, durable, and effective system performance.

Related Standards

ASTM D7466/D7466M-23 references and aligns with several other ASTM geosynthetics and testing standards, reinforcing broad industry applicability:

• ASTM D4439 - Terminology for Geosynthetics: Standardizes terminology across geosynthetics testing procedures.
• ASTM D5994/D5994M - Test Method for Measuring Core Thickness of Textured Geomembranes: Complementary measurement for understanding full product dimensions.
• ASTM E177 - Practice for Use of the Terms Precision and Bias in ASTM Test Methods: Provides guidance on statistical concepts for laboratory testing.
• ASTM E691 - Practice for Conducting an Interlaboratory Study: Supports precision assessment for test methodologies.
• ASTM E2554 - Practice for Estimating and Monitoring the Uncertainty of Test Results: Guidance for laboratories in controlling and reporting test uncertainty.

Conclusion

ASTM D7466/D7466M-23 is essential for anyone involved in geomembrane manufacturing, quality control, installation, or inspection. By adopting this standardized approach to asperity height measurement, stakeholders can ensure consistent product quality, compliance with project specifications, and reliable long-term performance of textured geomembrane systems. For complete guidance and official provisions, users should always consult the full ASTM standard text.

Keywords: asperity height, geomembrane, textured geomembrane, geosynthetics, ASTM D7466, surface roughness, geotechnical engineering, quality control, liner systems, environmental containment

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: D7466/D7466M − 23
Standard Test Method for
Measuring Asperity Height of Textured Geomembranes
This standard is issued under the fixed designation D7466/D7466M; 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 E2554 Practice for Estimating and Monitoring the Uncer-
tainty of Test Results of a Test Method Using Control
1.1 This test method covers a procedure to measure the
Chart Techniques
asperity height of textured geomembranes.
1.2 This test method does not provide for measurement of
3. Terminology
the spacing between the asperities nor of the complete profile
3.1 For definitions of other terms used in this test method,
of the textured surface.
refer to Terminology D4439.
1.3 The values stated in either SI units or inch-pound units
3.2 Definitions:
are to be regarded separately as standard. The values stated in
3.2.1 asperity, n—the individual projections of polyethylene
each system are not necessarily exact equivalents; therefore, to
that extend above the core surface of a textured geomembrane
ensure conformance with the standard, each system shall be
resulting in the textured surface profile.
used independently of the other, and values from the two
3.2.2 core thickness, n—the average thickness of a textured
systems shall not be combined.
geomembrane as measured using Test Method D5994/
1.4 This standard does not purport to address all of the
D5994M.
safety concerns, if any, associated with its use. It is the
3.2.3 geomembrane, n—an essentially impermeable geosyn-
responsibility of the user of this standard to establish appro-
thetic composed of one or more synthetic sheets. D4439
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3.2.4 setting block, n—the component part of a depth gauge
1.5 This international standard was developed in accor-
that rests on top of the asperities.
dance with internationally recognized principles on standard-
3.2.5 thickness, n— the perpendicular distance between one
ization established in the Decision on Principles for the
surface and its opposite.
Development of International Standards, Guides and Recom-
3.2.6 thickness gauge contact point, n—the tip of a thick-
mendations issued by the World Trade Organization Technical
ness gauge which contacts the base sheet of the geomembrane
Barriers to Trade (TBT) Committee.
surface.
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
4.1 The asperity height of a textured geomembrane is
D4439 Terminology for Geosynthetics
measured with a depth gauge, the setting block of which rests
D5994/D5994M Test Method for Measuring Core Thickness
on the top of the asperities while the contact point extends to
of Textured Geomembranes
the sheet’s core surface.
E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
4.2 The asperity height of a textured geomembrane is
E691 Practice for Conducting an Interlaboratory Study to
calculated as the average value of ten (10) individual measure-
Determine the Precision of a Test Method
ments taken across the roll width of the sample under investi-
gation.
This test method is under the jurisdiction of ASTM Committee D35 on
5. Significance and Use
Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomem-
branes.
5.1 The asperity height is an index property used to quantify
Current edition approved Nov. 1, 2023. Published December 2023. Originally
one of the physical attributes related to the surface roughness
approved in 2008. Last previous edition approved in 2015 as D7466/D7466M – 10
ɛ1
of textured geomembranes.
(2015) . DOI: 10.1520/D7466_D7466M-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.2 This test method is applicable to all currently available
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
textured geomembranes that are deployed as manufactured
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. geomembrane sheets.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7466/D7466M − 23
6. Apparatus
6.1 Depth Gauge—The depth gauge shall consist of three
components that conform the requirements of this section: a
digital or dial indicator, a setting block, and a contact point
with extension.
6.1.1 Digital/Dial Indicator—Capable of measuring to a
depth of at least 2.5 mm [0.10 in.] with an accuracy of
60.025 mm [0.001 in.].
6.1.2 Setting Block—The setting block shall have a base
dimension of 50 mm to 63.5 mm long by 20 mm to 12.7 mm
wide [2.0 in. to 2.5 in. long by 0.75 in. to 0.50 in. wide] and a
height of 15 mm [0.60 in.]. FIG. 2 Contact Point
6.1.3 Contact Point with Extension—The contact point is
1.3 mm [0.051 in.] in diameter with the tip tapered to a point.
An extension of approximately 17 mm [0.66 in.] is required to
achieve the necessary travel beyond the base surface of the
setting block. The contact point should protrude at least 10 mm
below the setting block when not in use in order to ensure that
a competent “zero” setting is achieved. See Figs. 1-3.
6.1.4 Mass of Assembly—The mass of the depth gauge fully
assembled with the dial indicator, setting block, and contact
point with extension should not exceed 300 g.
FIG. 3 Contact Extension
7. Sampling
7.1 Sample and Specimens—For the sample, take a full-
8. Conditioning and Test Conditions
width sample at least 75 mm [3 in.] wide. Exclude the inner
and outer wraps of the roll or any material not representative of
8.1 Bring the specimens to temperature equilibrium at 21 6
the sample. Either the entire strip may be tested or individual 2 °C [70 6 4 °F] and at a relative humidity of 60 6 10 %.
test specimens may be taken from this sample, with a minimum
8.2 Perform the test at the above conditions.
diameter of 75 mm [3 in.], spaced such that a total of ten (10)
asperity height determinations will be made approximately
9. Procedure
evenly across the sample.
9.1 Test the conditioned specimens in the standard labora-
7.2 Sample Labeling—For textured geomembrane samples
tory atmosphere specified in 8.1.
that are textured on both sides, identify one surface as “Side A”
9.2 Place the depth gauge on a flat, smooth, rigid supporting
and the other as “Side B.” Side A should correspond to the
surface to zero the contact point with the bottom of the setting
outside surface of the product when on the parent roll, and Side
block.
B the inside surface whenever this relationship is known.
9.3 Place the geomembrane specimen being tested on a flat,
Obtain and record sample identification.
smooth, rigid supporting surface, being vigilant to keep the
specimen flat for the measurements. For two side textured
geomembranes, measure the asperity height of Side A first.
9.4 Place the depth gauge on the surface of the textured
geomembrane specimen, with the long axis of the setting block
perpendicular to the machine direction of the roll. Do not apply
downward hand pressure on the gauge as this would compress
the asperities under the setting block.
9.5 Allow the contact point to come into contact with the
“low spots” or “valleys” in between the asperities, or into the
indentations of the textured surface(s). Move the depth gauge
slightly on the tes
...

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.
´1
Designation: D7466/D7466M − 10 (Reapproved 2015) D7466/D7466M − 23
Standard Test Method for
Measuring Asperity Height of Textured Geomembranes
This standard is issued under the fixed designation D7466/D7466M; 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—Designation was changed to dual and units information was corrected editorially in June 2015.
1. Scope
1.1 This test method covers a procedure to measure the asperity height of textured geomembranes.
1.2 This test method does not provide for measurement of the spacing between the asperities nor of the complete profile of the
textured surface.
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 and healthsafety, 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.
2. Referenced Documents
2.1 ASTM Standards:
D4439 Terminology for Geosynthetics
D5994/D5994M Test Method for Measuring Core Thickness of Textured Geomembranes
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2554 Practice for Estimating and Monitoring the Uncertainty of Test Results of a Test Method Using Control Chart Techniques
3. Terminology
3.1 For definitions of other terms used in this test method, refer to Terminology D4439.
3.2 Definitions:
This test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.
Current edition approved May 1, 2015Nov. 1, 2023. Published June 2015December 2023. Originally approved in 2008. Last previous edition approved in 20102015 as
ɛ1
D7466/D7466M – 10 (2015) D7466-10. DOI: 10.1520/D7466_D7466M-10R15E01. DOI: 10.1520/D7466_D7466M-23.
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
D7466/D7466M − 23
3.2.1 asperity, n—the individual projections of polyethylene that extend above the core surface of a textured geomembrane
resulting in the textured surface profile.
3.2.2 core thickness, n—the average thickness of a textured geomembrane as measured using Test Method D5994/D5994M.
3.2.3 geomembrane, n—an essentially impermeable geosynthetic composed of one or more synthetic sheets. D4439
3.2.4 setting block, n—the component part of a depth gauge that rests on top of the asperities.
3.2.5 thickness, n— the perpendicular distance between one surface and its opposite.
3.2.6 thickness gauge contact point, n—the tip of a thickness gauge which contacts the base sheet of the geomembrane surface.
4. Summary of Test Method
4.1 The asperity height of a textured geomembrane is measured with a depth gauge, the setting block of which rests on the top
of the asperities while the contact point extends to the sheet’s core surface.
4.2 The asperity height of a textured geomembrane is calculated as the average value of ten (10) individual measurements taken
across the roll width of the sample under investigation.
5. Significance and Use
5.1 The asperity height is an index property used to quantify one of the physical attributes related to the surface roughness of
textured geomembranes.
5.2 This test method is applicable to all currently available textured geomembranes that are deployed as manufactured
geomembrane sheets.
6. Apparatus
6.1 Depth Gauge—The depth gauge shall consist of three components that conform the requirements of this section; a section: a
digital or dial indicator, a setting block, and a contact point with extension.
6.1.1 DialDigital/Dial Indicator—Capable of measuring to a depth of at least 2.5 mm [0.10 in.] with an accuracy of 60.025 mm
60.025 mm [0.001 in.].
6.1.2 Setting Block—The setting block shall have a base dimension of 50 mm to 63.5 mm long by 20 mm to 12.7 mm wide [2.0
in. to 2.5 in. long by 0.75 in. to 0.50 in. wide] and a height of 15 mm [0.60 in.].
6.1.3 Contact Point with Extension—The contact point is 1.3 mm [0.051 in.] in diameter with the tip tapered to a point. An
extension of approximately 17 mm [0.66 in.] is required to achieve the necessary travel beyond the base surface of the setting
block. The contact point should protrude at least 10 mm below the setting block when not in use in order to ensure that a competent
“zero” setting is achieved. See Figs. 1-3.
6.1.4 Mass of Assembly—The mass of the depth gauge fully assembled with the dial indicator, setting block, and contact point with
extension should not exceed 300 g.
7. Sampling
7.1 Sample—Sample and Specimens—For the sample, take a full width full-width sample at least 75-mm [3-in.] 75 mm [3 in.]
wide. Exclude the inner and outer wraps of the roll or any material not representative of the sample. Either the entire strip may
be tested or individual test specimens may be taken from this sample, with a minimum diameter of 75 mm [3 in.], spaced such
that a total of ten (10) asperity height determinations will be made approximately evenly across the sample.
7.2 Sample Labeling—For textured geomembrane samples that are textured on both sides, identify one surface as “Side A” and
D7466/D7466M − 23
FIG. 1 Dial Indicator Asperity Height Test Gauge
FIG. 2 Contact Point
FIG. 3 Contact Extension
the other as “Side B.” Side A should correspond to the outside surface of the product when on the parent roll, and Side B the inside
surface whenever this relationship is known. Obtain and record sample identification.
8. Conditioning and Testing Test Conditions
8.1 Bring the specimens to temperature equilibrium at 21 6 2°C2 °C [70 6 4°F]4 °F] and at a relative humidity of 60 6 10 %.
8.2 Perform the test at the above conditions.
9. Procedure
9.1 Test the conditioned specimens in the standard laboratory atmosphere specified in 8.1.
9.2 Place the depth gauge on a flat, smooth, rigid supporting surface to zero the contact point with the bottom of the setting block.
D7466/D7466M − 23
9.3 Place the geomembrane specimen being tested on a flat, rigid, supporting surfacesmooth, rigid supporting surface, being
vigilant to keep the specimen flat for the measurements. For two side textured geomembranes, measure the asperity height of Side
A first.
9.4 Place the depth gauge on the surface of the textured geomembrane specimen, with the long axis of the setting block
perpendicular to the machine direction of the roll. Do not apply downward hand pressure on the gauge as this would compress the
asperities under the setting block.
9.5 Place the depth gauge on the surface of the textured geomembrane specimen, with the lo
...