ASTM D8424-21

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:D8424 −21
Standard Guide for
Retroreflective Composite Optics Laboratory Procedures
This standard is issued under the fixed designation D8424; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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
2.1 ASTM Standards:
1.1 This guide presents a series of options for evaluating
C702PracticeforReducingSamplesofAggregatetoTesting
lot-to-lot consistency of retroreflective composite optics of the
Size
same type and form from the same manufacturer and does not
D1921Test Methods for Particle Size (Sieve Analysis) of
recommend any specific course of action to be taken. This
Plastic Materials
guide is meant to increase the awareness of information and
D2486Test Methods for Scrub Resistance of Wall Paints
approachesandisnotmeanttorecommendanyspecificcourse
D7428Test Method for Resistance of Fine Aggregate to
of action per ASTM’s Form and Style for ASTM Standards
Degradation by Abrasion in the Micro-Deval Apparatus
definition for a Guide.
E1349Test Method for Reflectance Factor and Color by
1.1.1 This guide does not determine lab procedure selection
Spectrophotometry Using Bidirectional (45°:0° or 0°:45°)
or acceptance criteria for a specific retroreflective composite
Geometry
opticsproductforitsintendeduse.Itistheresponsibilityofthe
E1710Test Method for Measurement of Retroreflective
manufacturer and customer to negotiate these details based on
Pavement Marking Materials with CEN-Prescribed Ge-
their specific needs.
ometry Using a Portable Retroreflectometer
1.1.2 This guide is not intended to predict in-service perfor-
2.2 AASHTO Standards:
mance levels.
AASHTO TP-130-18Producing Draw Down Panels and
1.1.3 This guide is not intended for comparison of different
Measuring the Coefficient of Retroreflected Luminance
types of composite optics or manufacturers of composite
(R ) of Pavement Markings in a Laboratory Panel
L
optics.
3. Terminology
1.2 Units—The values stated in SI units are to be regarded
as standard. The values given in parentheses after SI units are
3.1 Definitions:
provided for information only and are not considered standard.
3.1.1 installed pavement markings, n—pavement markings
applied to a road surface for the purpose of guiding traffic.
1.3 This standard does not purport to address all of the
3.1.2 pavement marking material, n—a pigmented binder
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- system used for lane delineation for highways, parking lots,
and other areas subject to vehicular traffic; applicable pave-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. ment marking materials include waterborne traffic paint, sol-
vent borne traffic paint, thermoplastic, plural component such
1.4 This international standard was developed in accor-
as epoxy, modified epoxy, polyurea, and methyl methacrylate.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the 3.1.3 pavement marking sample, n—a properly cured pave-
Development of International Standards, Guides and Recom-
ment marking of specified width, length, and thickness applied
mendations issued by the World Trade Organization Technical to an appropriate, substrate panel; the pavement marking has
Barriers to Trade (TBT) Committee.
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
This guide is under the jurisdiction of ASTM Committee D01 on Paint and Standards volume information, refer to the standard’s Document Summary page on
Related Coatings, Materials, and Applications and is the direct responsibility of the ASTM website.
Subcommittee D01.44 on Traffic Coatings. Available from American Association of State Highway and Transportation
Current edition approved Nov. 1, 2021. Published December 2021. DOI: Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,
10.1520/D8424-21. http://www.transportation.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8424−21
drop-on particles embedded in the surface of the marking to 6.2 Isolate a retroreflective composite optics sample large
provide various performance characteristics such as enough for all lab procedures.
retroreflectivity, color, and skid resistance.
3.1.3.1 Discussion—For the purpose of measuring retrore- 7. Retroreflective Composite Optics Lab Procedures
flectivity after scrubbing procedures in this document, the size
7.1 Bulk Retroreflective Composite Optics Procedures—
of the scrub area of the pavement marking sample needs to
These procedures are intended for lot-to-lot comparison of
meet or exceed the dimensional requirements for the retrore-
retroreflective composite optics for purposes of ensuring con-
flectometer and satisfy the minimum measurement area re-
sistency. These lab procedures are not intended to predict
quirements of Test Method E1710 (50 cm ). For practical
on-road retroreflectivity performance as on-road retroreflectiv-
purposes, an area 70 mm by 200 mm (2.8 in. by 7.9 in.) meets
ity performance is impacted by many application and environ-
the requirements for most commonly used retroflectometers,
mental factors.
andexceedstheminimumrequirementsofTestMethodE1710.
7.1.1 Retroreflective Composite Optics Bulk Color—This is
Refer to your retroreflectometer manufacturer for details.
a lab procedure for measuring the color of the retroreflective
3.1.4 retroreflective composite optics, n—a multi-
composite optics in bulk form. A sample of retroreflective
component retroreflective optical construction including but
composite optics is placed in a small container and the color is
not limited to:
measuredusingahandheldspectrophotometerperTestMethod
(1)A core covered with a pigmented adhesive and small
E1349 using a 0/45, 45/0 instrument with CIE illuminant D65
glass or ceramic optical beads.
and 2° observer.
(2)Aclusterofopticalceramicorglassbeadsdistributedin
7.1.1.1 Into a petri dish approximately 12.7 mm ( ⁄2 in.)
a polymeric matrix.
deep and 88 mm (3 ⁄2 in.) diameter, add about 50 g or
(3)An optical glass bead core, covered with a pigmented
approximately 40 mL of retroreflective composite optics.
adhesive and small glass or ceramic optical beads.
7.1.1.2 Tap and shake the petri dish to level the layer of
3.1.5 substrate panel, n—a panel used for the application of
optics in the dish.
a pavement marking material to produce a pavement marking
7.1.1.3 Place the port of the handheld spectrophotometer on
sample; the panel should be flat, dimensionally stable, com-
the horizontal surface of retroreflective composite optics.
patible with the pavement marking material, bonds adhesively
7.1.1.4 Take a measurement.
to the pavement marking material, and a dimension which
7.1.1.5 Record Y, x, y.
complies with the sample size of the washability tester (scrub
7.1.2 Retroreflective Composite Optics Roller Mill Perfor-
tester) and the measurement profile of Test Method E1710
mance (Weight Retention)—This is a lab procedure for mea-
(100mm (4 in.) minimum wide by 250 mm (10 in.) minimum
suring retroreflective composite optics performance in a roller
long panel).
mill as it relates to crushing and grinding. A retroreflective
composite optics sample of known weight is placed in a
4. Summary of Guide
ceramicballmillwithgrindmediaandrolledataspecifiedrate
4.1 This guide provides laboratory procedures, for retrore-
for a specified number of revolutions. The sample is sieved,
flective composite optics to: (1) evaluate retroreflective com-
cleaned, dried, and weighed. The result is reported as percent
positeopticsasreceivedbythepurchaserinbulkform,and(2)
weight (% wt.) retention compared to the original sample
evaluateretroreflectivecompositeopticsappliedinapavement
weight.
marking sample.
7.1.2.1 Measure a 250 mL sample of retroreflective com-
4.2 Determining which lab procedures to select and the posite optics.
acceptance criteria is outside the scope of this guide. 7.1.2.2 Weigh the 250 mL sample and record the weight.
7.1.2.3 Place retroreflective composite optics in a ceramic
5. Significance and Use
ball mill jar with outside dimensions approximately 15.2 cm
long by 15.2 cm diameter, excluding the mouth and neck.
5.1 The nighttime retroreflective properties of pavement
7.1.2.4 Carefully place 1000 g of 19 mm ( ⁄4 in.) diameter
markings are known to improve driving safety. Retroreflective
clean ceramic balls into the ceramic ball mill jar with the
composite optics have been developed to improve retroreflec-
sample.
tivity in dry and rainy wet conditions. For customers purchas-
7.1.2.5 Put the lid on the ball mill and secure.
ing these materials it’s important to verify the consistency and
performance. This guide provides a set of laboratory proce-
7.1.2.6 Put the ball mill on a jar roller.
dureswhichcanbeselectedindividuallyortogethertoevaluate
7.1.2.7 Roll the ceramic ball mill jar containing retroreflec-
lot-to-lot consistency of composite optics of the same type and
tive composite optics and ceramic balls for 1500 revolutions at
manufacturer.Thesearenotin-serviceperformanceprocedures
100 rpm.
and don’t necessarily predict in-service performance.
7.1.2.8 Pour the contents of the ball mill jar into a #3 sieve
to separate the ceramic balls from the sample.
6. Sampling and Sample Preparation
7.1.2.9 Sieve the retroreflective composite optics to remove
6.1 To obtain representative samples from packaged fines and debris generated by milling. A sieve with opening
containers, blenders, or storage tanks, sampling methods out- size approximately half the diameter of the smallest retrore-
lined in Practice C702 should be followed. flective composite optics in the sample is recommended.
D8424−21
7.1.2.10 Clean and dry the sample per (Annex A1). Weigh 7.2.3.7 Perform the scrub procedure for 400 cycles at 40
the clean and dried sample. cycles per minute on the drawdown.
7.1.2.11 Divide the weight of the processed sample by the 7.2.3.8 When the procedure is finished, remove the draw-
original sample weight and multiply by 100. down and measure the coefficient of retroreflected luminance
(processed wt./original wt.) × 100 = percent weight retention (R ) using the retroreflectometer.
L
7.2.4 Wet Scrub Durability Procedure—This procedure
7.2 Retroreflective Composite Optics Procedures in Pave-
simulates abrasion exposure of the retroreflective composite
ment Marking Material:
optics while constantly wet and evaluates the performance
7.2.1 These procedures are intended f
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