ASTM D7681-11

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D7681 − 11
StandardTest Method for
Measuring Gradation of Glass Spheres Using a Flowing
Stream Digital Image Analyzer
This standard is issued under the fixed designation D7681; 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 3. Terminology
1.1 This test method covers the determination of the grada- 3.1 Definitions:
tion (size distribution) of glass spheres used in pavement 3.1.1 flowing stream digital image analyzer, n—a computer
marking systems using a Flowing Stream Digital Analyzer. controlled particle size analyzer employing a high resolution
Typical gradations for pavement marking systems are defined digital imaging device and computer image processing soft-
in ranges from Type 0 through 5 in AASHTO M247-08. ware to do photo optical single particle counting and particle
size analysis.
1.2 Thistestmethodprovidesforthepresentationofthesize
3.1.2 gradation of glass beads, n—the measurement of the
data in a variety of formats to the requirements of the agency
size(diameter)ofglassbeadsandtheirsubsequentpresentation
pavement marking material specification. For most specifica-
in ranges between ASTM standard sieve sizes and/or micron
tions the standard format is to present the size data as “Percent
designation starting with the largest to the smallest; the ranges
Retained” or “Percent Passing” relative to a series of standard
are listed as “percent passing” and “percent retained.”
US sieve sizes.
1.3 The values stated in SI units are to be regarded as
4. Summary of Test Method
standard. No other units of measurement are included in this
4.1 The glass particles are run through a flowing stream
standard.
digital image analyzer, a measuring system for determining the
1.4 This standard does not purport to address all of the
gradation (size distribution) of dry, free flowing and harmless
safety concerns, if any, associated with its use. It is the
bulk products. The total recommended measuring range is
responsibility of the user of this standard to establish appro-
between 100 µm and 2.36 mm. The operating test method uses
priate safety and health practices and determine the applica-
photo optical single particle counting technology for the image
bility of regulatory limitations prior to use.
processing. The measurement time depends on the quantity of
material to be measured, the width of the metering feeder and
2. Referenced Documents
the mean grain size. The quantity of material to be measured
2.1 ASTM Standards:
depends on the grain size and the width of the metering feeder.
B215 Practices for Sampling Metal Powders
Typical measuring times are approximately 2 to 10 min.
E177 Practice for Use of the Terms Precision and Bias in
5. Significance and Use
ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to
5.1 The gradation (size distribution) of glass beads has a
Determine the Precision of a Test Method
significant influence on the retroreflective efficiency of a
2.2 AASHTO Standards:
pavement marking system.
AASHTO M247-08 Standard Glass Beads Used in Traffic
5.2 This test method is for the characterization of the
Markings
gradation (size distribution) of glass beads for the purpose of
compliance testing against standard specification for glass
This test method is under the jurisdiction of ASTM Committee D01 on Paint
beads in pavement marking applications.
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.44 on Traffic Coatings.
5.3 While there are potential industrial applications for this
Current edition approved Jan. 1, 2011. Published February 2011. DOI: 10.1520/
test method beyond the measurement of gradation (size distri-
D7681–11
2 bution) of glass beads for pavement markings, those are
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
beyond the scope of this standard.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 6. Apparatus
Available from American Association of State Highway and Transportation
6.1 Typical Instrument Operating Conditions (Fig. 1):
Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,
http://www.transportation.org. 6.1.1 Environmental temperature — 10°C.40°C.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7681 − 11
FIG. 1 Typical Apparatus
6.1.2 Air Humidity — 80 % maximum relative humidity at 11. Conditioning
temperatures up to 30°C, linear decrease to 50 % maximum
11.1 Sample Preparation:
relative humidity at a temperature of 40°C.
11.1.1 Use a sample splitter, if necessary, to reduce the
6.1.3 Height of installation and operation — maximum 300
amount of sample to the appropriate size.
m above sea level.
11.1.2 Pour entire glass bead sample into the glass beaker or
6.1.4 Installation location — place the particle analyzer on
suitable container.
a firm, horizontal, vibration free surface.
11.1.3 Assure glass beads are moisture free and free flow-
6.1.5 Light conditions — avoid strong direct external light
ing.
on the particle measurement shaft or on the cameras.
NOTE 1—Check with instrument manufacturer for suggestions on how
6.1.6 This test method is designed for indoor or outdoor use
tobestsetupanysoftwarethatcomeswiththeirinstrument.Settingupthe
instrument software properly will speed up any glass sphere gradation
as prescribed by the manufacturer’s design and instructions.
measurements and allow for meaningful reports.
7. Hazards
12. Procedure
7.1 General Safety Information:
12.1 Load the sample into the feeder of the flowing stream
7.1.1 Operate the instrument in accordance with the manu-
digitalimageanalyzer.Theanalyzersoftwareallowstheuserto
facturer’s recommendations following all required safety pre-
carry out his measurements quickly and without error. All
cautions.
measuring and analysis parameters are determined initially and
8. Sampling, Test Specimens, and Test Units
set into the computer program. Different task files are created
for different specifications.
8.1 Obtain a minimum of approximately 50 6 5 g specimen
NOTE 2—When assigning sieve ranges to be used in a task file, the user
of the glass beads to be tested for gradation (size distribution).
must use the ASTM mesh sieve choice, not the W. S. Tyler mesh. The
For larger sizes of glass spheres, such as Type III and larger,
quantity of the material to be measured has to be placed into the funnel of
whose gradation is defined inAASHTO M247-08, 75 to 125 g
the metering feeder. The material handling mechanisms must not restrict
samples shall be used.
or segregate product flow in any way that allows for a non-representative
flow of product through the measurement zone.
8.2 In order to obtain representative samples when sam-
12.2 After the task file has been defined only a minimal
pling from packaged containers, blenders or storage tanks,
number of operative steps are required for carrying out a
methods outlined in Practices B215 shall be followed.
measurement. They are: (a) filling a quantity of the material to
9. Preparation of Apparatus be measured into the funnel to the metering feeder, (b) calling
the measurement and choosing the task file, (c) confirming the
9.1 Follow the manufacturer’s instructions for the particle
suggested comments or entering new comments, (d) starting
analyzer being used.
the measurement, and (e) reading the result or printing a
10. Calibration and Standardization record. The measured result is available a few moments after
the measurement is completed and can be displayed in many
10.1 The particle analyzer, in most cases, will be calibrated
forms, and be printed and saved with the help of the PC.
by the manufacturer prior to shipping. Re-calibration might
become necessary occasionally, for example, after the trans-
13. Report
portation of the instrument or if required by quality manage-
mentregulations.Inthiscase,followthecalibrationprocedures 13.1 Report the percentage of particles in each size classi-
as outlined in the manufacturer’s instruction manual. fication.
D7681 − 11
14. Precision and Bias 14.1.3 Reproducibility Limit (R)—Two test results shall be
judged not equivalent if they differ by more than the “R” value
14.1 Precision—A round-robin study has been used to
for that material; “R” is the interval representing the critical
generate a precision statement.
difference between two test results for the same material,
14.1.1 The precision of this test method is based on an
obtai
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