ASTM D2746/D2746M-18(2023)

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: D2746/D2746M − 18 (Reapproved 2023)
Standard Test Method for
Staining Tendency of Asphalt (Stain Index)
This standard is issued under the fixed designation D2746/D2746M; 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 D36/D36M Test Method for Softening Point of Bitumen
(Ring-and-Ball Apparatus)
1.1 This test method covers the determination of the stain-
D140/D140M Practice for Sampling Asphalt Materials
ing tendency of asphalt and the assignment of a stain index
E230/E230M Specification for Temperature-Electromotive
proportional to the extent of staining observed.
Force (emf) Tables for Standardized Thermocouples
1.2 This test method is applicable to asphalts having ring-
E1137/E1137M Specification for Industrial Platinum Resis-
and-ball softening points of 85 °C [185 °F] or greater.
tance Thermometers
E2251 Specification for Liquid-in-Glass ASTM Thermom-
NOTE 1—This test method may be modified for use with other
bituminous materials with softening points less than 85 °C [185 °F] by
eters with Low-Hazard Precision Liquids
using a different temperature than specified in Section 7 by agreement of
the interested parties. The report of results from such a test may cite this
3. Summary of Test Method
method but must clearly state the temperature employed in the exception
and acknowledge that the interpretation of results in Section 9 and the
3.1 A horizontal disc of asphalt, cast in a brass retaining
precision and bias stated in Section 10 may not apply.
ring, is placed on a sheet of filter paper supported on a flat plate
1.3 The values stated in either SI units or inch-pound units
and heated at 80 °C [175 °F] for 120 h. The diameter of the
are to be regarded separately as standard. The values stated in
resulting stained circle on the paper is compared to the inside
each system may not be exact equivalents; therefore, each
diameter of the brass ring to determine the staining character-
system shall be used independently of the other. Combining
istic of the asphalt. The stain index is the difference between
values from the two systems may result in nonconformance
the diameter of the stained circle and the initial disc diameter
with the standard.
measured to the nearest 0.5 mm [ ⁄64 in.].
1.4 This standard does not purport to address the safety
4. Significance and Use
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety,
4.1 This test method measures the tendency for oil compo-
health, and environmental practices and determine the appli-
nents to separate spontaneously from asphalt. The separation of
cability of regulatory limitations prior to use.
oil components can cause staining in asphalt roofing products
1.5 This international standard was developed in accor-
and adjacent materials in storage and use.
dance with internationally recognized principles on standard-
4.2 The stain index is related to the thermal stability of the
ization established in the Decision on Principles for the
asphalt. Higher stain index values indicate lower stability and
Development of International Standards, Guides and Recom-
greater tendency for staining.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4.3 Use this procedure to determine the staining tendency of
asphalt and to compare the results against a material for which
2. Referenced Documents
the staining tendency is known.
2.1 ASTM Standards:
5. Apparatus
5.1 Rings—Square shouldered brass retaining rings con-
forming to the dimensions required for use in the ring-and-ball
This test method is under the jurisdiction of ASTM Committee D08 on Roofing
and Waterproofing and is the direct responsibility of Subcommittee D08.02 on
softening point apparatus (see Fig. 1(a) of Test Method
Steep Roofing Products and Assemblies.
D36/D36M).
Current edition approved May 1, 2023. Published May 2023. Originally
5.1.1 The inside diameter of the ring to be placed in contact
approved in 1991. Last previous edition approved in 2018 as D2746/D2746M – 18.
DOI: 10.1520/D2746_D2746M-18R23. with the filter paper during the test is 16 mm [ ⁄64 in.].
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
NOTE 2—This test method depends on accurate measurement of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on diameter and precise alignment of the face and rim of the ring on a flat
the ASTM website. surface. Therefore, deformed rings must not be used.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2746/D2746M − 18 (2023)
5.2 Pouring Plate—A flat, smooth, brass plate approxi- 7.2.1 The known material (Note 3) must be placed on the
mately 50 by 75 mm [2 by 3 in.]. same piece of filter paper and support plate as the sample(s)
being tested.
5.3 Paper—Filter paper of the standard double acid-washed
analytical grade. NOTE 3—The “known” material for the purpose of this test is a material
whose staining tendency is known to the investigator and which is used to
5.3.1 The filter paper must be of sufficient area to accom-
compare with the material being tested (see also Note 6).
modate the number of samples and the known material
7.2.2 Identify each asphalt sample and known material by
arranged as described in 7.3.
appropriately marking the filter paper in pencil near each ring.
5.4 Support Plate—A flat, clean, smooth metal plate ap-
7.3 Place the entire assembly on the support plate in the
proximately 1.5 mm [ ⁄16 in.] thick and area at least sufficient to
oven, preheated to 80 6 1 °C [175 6 2 °F], and allow to
support the size of filter paper being used.
remain at that temperature for 120 6 1 h.
5.5 Oven—A constant temperature oven capable of main-
7.4 Remove the assembly on the support plate from the
taining the test temperature of 80 °C [175 °F] within 61 °C
oven and allow to cool to room temperature (about 24 °C
[62 °F].
[75 °F]).
5.6 Thermometric Device—The thermometric device used
7.5 Remove the ring and the asphalt disc from the filter
shall be at least: (1) of equal accuracy to that of the S12C
...