ASTM D7971-20

Standard Guide for Measuring Roundness of Glass Spheres Using a Flowing Stream Digital Image Analyzer

SIGNIFICANCE AND USE
4.1 The roundness of glass beads has a significant influence on the retroreflective efficiency of a pavement marking system.  
4.2 The guide is for the characterization of the roundness of glass beads for the purpose of compliance testing against standard specification for glass beads in pavement marking applications.  
4.3 While there are potential industrial applications for this guide beyond the measurement of roundness of glass beads for pavement markings, those are beyond the scope of this standard.
SCOPE
1.1 This guide covers the determination of the roundness of glass spheres used in pavement marking systems using a flowing stream digital analyzer. Typical gradations for pavement marking systems are defined in ranges from Type 0 through 5 in AASHTO M247.  
1.2 This guide provides for the presentation of roundness data in a variety of formats to the requirement of the agency pavement marking material specification. For most specifications the standard format is to present the roundness data as Percent True Spheres relative to a series of standard ASTM sieve sizes.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
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-May-2020
• ICS: 93.080.20 - Road construction materials
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.44 - Traffic Coatings

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: D7971 − 20
Standard Guide for
Measuring Roundness of Glass Spheres Using a Flowing
1
Stream Digital Image Analyzer
This standard is issued under the fixed designation D7971; 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.
3
1. Scope 2.2 AASHTO Standard:
AASHTO M247 Standard Glass Beads Used in Traffic
1.1 This guide covers the determination of the roundness of
Markings
glass spheres used in pavement marking systems using a
4
2.3 ISO Standards:
flowing stream digital analyzer. Typical gradations for pave-
ISO 9276–6 Representation of results of particle size analy-
ment marking systems are defined in ranges from Type 0
sis — Part 6: Descriptive and quantitative representation
through 5 in AASHTO M247.
of particle shape and morphology
1.2 This guide provides for the presentation of roundness
ISO 13322–1 Particle size analysis — Image analysis meth-
data in a variety of formats to the requirement of the agency
ods — Part 1: Static image analysis methods
pavement marking material specification. For most specifica-
3. Terminology
tions the standard format is to present the roundness data as
Percent True Spheres relative to a series of standard ASTM
3.1 Flowing Stream Digital Analyzer:
sieve sizes.
3.1.1 A computer controlled particle analyzer employing a
high resolution digital imaging device and computer image
1.3 The values stated in SI units are to be regarded as
processingsoftwaretodophotoopticalsingleparticlecounting
standard. No other units of measurement are included in this
and particle size analysis.
standard.
3.2 Roundness of Glass Beads:
1.4 This standard does not purport to address all of the
3.2.1 Roundness, in the context of this guide, refers to the
safety concerns, if any, associated with its use. It is the
percentage of true spheres in a sample as a ratio of the total
responsibility of the user of this standard to establish appro-
number of particles measured.
priate safety, health, and environmental practices and deter-
3.2.2 Methods:
mine the applicability of regulatory limitations prior to use.
3.2.2.1 These are specific observations and calculations of
1.5 This international standard was developed in accor-
the streaming particles that combine to form a protocol for
dance with internationally recognized principles on standard-
measuring the percentage of true spheres within the sample.
ization established in the Decision on Principles for the
3.3 Aspect Ratio:
Development of International Standards, Guides and Recom-
3.3.1 Aspect ratio, often referred to as b/l or w/l, is one of
mendations issued by the World Trade Organization Technical
the several methods of determining roundness and is illustrated
Barriers to Trade (TBT) Committee.
in Fig. 1.
3.3.2 Aspect ratio will be the recommended method for the
2. Referenced Documents
majority of roundness measurements, especially when there
2
2.1 ASTM Standards:
exists a reasonable expectation that all of the particles being
B215 Practices for Sampling Metal Powders
measured have rounded surfaces and mostly resemble the
shape of a sphere.
3.4 Sphericity (also referred to as circularity):
1
This guide is under the jurisdiction of ASTM Committee D01 on Paint and
3.4.1 Sphericity is one of a number of methods of determin-
Related Coatings, Materials, and Applications and is the direct responsibility of
ing roundness and is illustrated in Fig. 2.
Subcommittee D01.44 on Traffic Coatings.
CurrenteditionapprovedJune1,2020.PublishedJuly2020.Originallyapproved
in 2015. Last previous edition approved in 2015 as D7971 – 15. DOI: 10.1520/
3
D7971-20. Available from American Association of State Highway and Transportation
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM http://www.transportation.org.
4
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D7971 − 20
3.5.2 Nominal covered area (set value of obscuration) is
calculated using the obscured area by particles divided
...

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: D7971 − 15 D7971 − 20
Standard Guide for
Measuring Roundness of Glass Spheres Using a Flowing
1
Stream Digital Image Analyzer
This standard is issued under the fixed designation D7971; 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 guide covers the determination of the roundness of glass spheres used in pavement marking systems using a flowing
stream digital analyzer. Typical gradations for pavement marking systems are defined in ranges from Type 0 through 5 in AASHTO
M247.
1.2 This guide provides for the presentation of roundness data in a variety of formats to the requirement of the agency pavement
marking material specification. For most specifications the standard format is to present the roundness data as Percent True Spheres
relative to a series of standard ASTM sieve sizes.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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 safety, health, and healthenvironmental 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
2.1 ASTM Standards:
B215 Practices for Sampling Metal Powders
3
2.2 AASHTO Standard:
AASHTO M247 Standard Glass Beads Used in Traffic Markings
4
2.3 ISO Standards:
ISO 9276–6 Representation of results of particle size analysis — Part 6: Descriptive and quantitative representation of particle
shape and morphology
ISO 13322–1 Particle size analysis — Image analysis methods — Part 1: Static image analysis methods
3. Terminology
3.1 Flowing Stream Digital Analyzer:
3.1.1 A computer controlled particle analyzer employing a high resolution digital imaging device and computer image
processing software to do photo optical single particle counting and particle size analysis.
3.2 Roundness of Glass Beads:
3.2.1 Roundness, in the context of this guide, refers to the percentage of true spheres in a sample as a ratio of the total number
of particles measured.
3.2.2 Methods:
1
This guide is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of Subcommittee
D01.44 on Traffic Coatings.
Current edition approved April 1, 2015June 1, 2020. Published April 2015July 2020. Originally approved in 2015. Last previous edition approved in 2015 as D7971 – 15.
DOI: 10.1520/D7971-15.10.1520/D7971-20.
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.
3
Available from American Association of State Highway and Transportation Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,
http://www.transportation.org.
4
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D7971 − 20
3.2.2.1 These are specific observations and calculations of the streaming particles that combine to form a protocol for measuring
the percentage of true spheres within the sample.
3.3 Aspect Ratio:
3.3.1 Aspect ratio, often referred to as b/l or w/l, is one of the several methods of determining roundness and is illustrated in
Fig. 1.
3.3.2 Aspect ratio will be the recommended method for the majority of roundness measurements, especially when there exists
a reasonable expectation that all of the particles being measured have rounded surfaces and mostly resemble the shape of a sphere.
3.4 Sphericity (also referred to as circularity):
3.4.1 Sphericity is one of a nu
...