ASTM D3461-97(2002)

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An American National Standard
Designation:D3461–97 (Reapproved 2002)
Standard Test Method for
Softening Point of Asphalt and Pitch (Mettler Cup-and-Ball
Method)
This standard is issued under the fixed designation D 3461; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Significance and Use
1.1 This test method covers the determination of the soft- 4.1 Asphalt and pitch do not go through a solid-liquid phase
ening point of asphalt and pitch in the range from 50 to 180°C change when heated, and therefore do not have true melting
by the cup-and-ball apparatus, and gives results comparable to points. As the temperature is raised, they gradually soften or
those obtained by Test Method D 36. become less viscous. For this reason, the determination of the
softening point must be made by an arbitrary, but closely
NOTE 1—If the softening point of asphalt by this Mettler cup-and-ball
defined, method if the test values are to be reproducible.
method fails to meet specified requirements, tests may be rerun using the
4.2 This test method is useful in determining the consis-
Test Method D 36 (ring-and-ball) softening point apparatus as a referee
method. tency as one element in establishing the uniformity of ship-
ments or sources of supply.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Apparatus
responsibility of the user of this standard to establish appro-
5.1 AMettler dropping point cell can be used to determine
priate safety and health practices and determine the applica-
softening points by this test method. These commercially
bility of regulatory limitations prior to use.
available instruments consist of a control unit with a digital
temperature indicator, matched furnace, sample cartridges, and
2. Referenced Documents
accessories. The control unit automatically regulates the heat-
2.1 ASTM Standards:
ing rate of the furnace. The softening point is indicated on the
A 314 Specification for Stainless Steel Billets and Bars for
2 readout, and the heating program stopped, when the sample
Forgings
flow triggers a photocell detector. A general view of the
D 36 Test Method for Softening Point of Bitumen (Ring-
3 components of the Mettler apparatus is shown in Fig. 1.
and-Ball Apparatus)
5.1.1 Control Unit—This unit shall provide a continuous,
D 140 Practice for Sampling Bituminous Materials
5 linear temperature increase from 25 to 250°C at a rate of
D 4296 Practice for Sampling Pitch
2°C/min. A digital readout shall indicate the temperature to
3. Summary of Test Method 0.1°C throughout.
5.1.2 Furnace Unit—This unit shall be capable of heating a
3.1 In this test method the softening point is defined as the
specimen cup assembly, as described in 5.1.3, at a linear rate of
temperature at which the specimen, suspended in a cylindrical
2 6 0.3°C/min. It shall include a sensing system capable of
cup with a 6.5-mm hole in the bottom and with a lead ball,
detecting the softening point with a precision of 0.1°C.
8 mm in diameter, centered on top of the sample in the cup,
5.1.3 Specimen Cup Assembly—A cup of chromium-plated
flows downward a distance of 19 mm to interrupt a light beam,
brass, or stainless steel conforming to the requirements for
as the sample is heated at a linear rate in air.
Type 303 (UNS 530300) as prescribed in Specification A 314,
with dimensions shown in Fig. 2. It shall be placed in the
This test method is under the jurisdiction of ASTM Committee D02 on assembly so that the test specimen will flow down a distance of
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
19 mm before interrupting a light beam and stopping the
D02.05.OF on Industrial Pitches.
heating program as the softening point is reached.
Current edition approved July 10, 1997. Published October 1997. Originally
e2
published as D 3461 – 76. Last previous edition D 3461 – 85 (1994) .
Annual Book of ASTM Standards, Vol 01.03.
Annual Book of ASTM Standards, Vol 04.04.
4 6
Annual Book of ASTM Standards, Vol 04.03. Available from the Mettler Toledo, Inc., Balances and Instruments, 69
Annual Book of ASTM Standards, Vol 05.02. Princeton-Hightstown Rd., Hightstown, NJ 08520-0071.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3461–97 (2002)
FIG. 1 General View of the Mettler FP-5/53
5.1.4 Lead Ball—A lead ball weighing 3.20 6 0.10 g. hygroscopic, it must be stored in a tightly sealed container, and
A32-caliber lead shot is suitable for this purpose. replaced with fresh material from a newly opened supply if
hydration or other contamination is suspected.
6. Reagents
7.3 Procedure:
6.1 Xylene, industrial grade. 7.3.1 Filling the Specimen Cup—Place the cup on a clean,
flat surface. Add a small amount of benzoic acid crystals and
7. Calibration of Mettler Apparatus
press down with a rod (4.5 mm in diameter). Check that the
bottom orifice is completely filled. Refill and repeat the
7.1 This step, required only occasionally, is designed to
pressing step until the cup is filled with benzoic acid. Remove
establish that the temperature indicated by the instrument is in
any crystals from the exterior of the cup.
agreement with a known standard.Aspecial cup with a bottom
orifice of 2.8 mm is used instead of the one prescribed for the 7.3.2 Heating—Preheat the Mettler furnace to 121°C, and
specimen testing. maintain it at that temperature. Place the cartridge assembly
7.2 Reagent—Use either analytical reagent or primary stan- containing the benzoic acid in position in the furnace, taking
dard grade benzoic acid for this calibration.As this material is care that the slits for the light beam are properly positioned.
D3461–97 (2002)
overheat.Removefromtheheatsourceassoonasthefoamhas
subsided. Proceed as directed in 9.1.
8.2.3 Crush air-dry lumps of pitch to a size of 6 to 12 mm.
Add the material to a container, having a height equal to or
exceeding its width, and having a volume of not less than
50 mL, until it is about half full. Place the container on a hot
plate, or in an oven or a bath. Do not use an open flame for
melting pitch. After melting is complete, stir gently but
thoroughly, avoiding incorporation of air bubbles. The maxi-
mum temperature of the molten pitch should not exceed the
expected softening point by more than 50°C. Any foam that
forms must be skimmed off.
8.3 Asphalt Sample Preparation:
8.3.1 Heat the sample, with care to prevent local overheat-
ing, constantly stirring until it has become sufficiently fluid to
pour. In no case, however, shall the temperature be raised more
than 110°C (200°F) above the expected softening point for
asphalt. Avoid incorporating air bubbles in the sample.
8.3.2 Bring the asphalt sample to the pouring temperature in
not more than 2 h.
FIG. 2 Specimen Cup
9. Test Specimen
Wait for temperature equilibration, that is, the furnace and the
9.1 Prepare the test specimen by slightly overfilling the
sampleareinequilibriumatthepresettemperature,butnotless
specimen cup, which rests on a brass plate. Keep the lip of the
than 30 s after inserting the cartridge, start the automatic
container close to the top of the cup to minimize entrainment
heating cycle at 0.2°C/min. The temperature will rise steadily
of air bubbles. Underpouring past the blade of a spatula is
at the correct rate until the drop point is reached, and then
helpful in this respect. Cool the specimen in the cup until firm,
remain steady on the readout.
under cold water if necessary.Trim the specimen flush with the
7.3.3 Cleaning—Immediately remove the cartridge assem-
top of the cup by pressing with a heated knife or spatula while
bly. Check to determine that the specimen
...