Designation: D4402/D4402M − 12

Standard Test Method for

Viscosity Determination of Asphalt at Elevated
Temperatures Using a Rotational Viscometer1
This standard is issued under the fixed designation D4402/D4402M; 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.
This standard has been approved for use by agencies of the Department of Defense.

1. Scope 3.1.2 filled asphalt, n—an asphalt blend that contains finely
1.1 This test method outlines a procedure for measuring the dispersed insoluble mineral matter.
apparent viscosity of asphalt from 38 to 260°C [100 to 500°F] 3.1.3 Newtonian liquid, n—a liquid for which the rate of
using a rotational viscometer and a temperature-controlled shear is proportional to the shearing stress. The constant ratio
thermal chamber for maintaining the test temperature. of the shearing stress to the rate of shear is the viscosity of the
1.2 The values stated in either SI units or inch-pound units liquid. The viscosity of a Newtonian liquid is therefore not
are to be regarded separately as standard. The values stated in dependent on its shear rate. If the ratio is not constant, the
each system may not be exact equivalents; therefore, each liquid is non-Newtonian. Many liquids exhibit both Newtonian
system shall be used independently of the other. Combining and non-Newtonian behavior, depending on the shear rate or
values from the two systems may result in non-conformance temperature, or both.
with the standard. 3.1.4 shear rate, n—the measure of the speed at which the
1.3 This standard does not purport to address all of the intermediate layers of the liquid move with respect to each
safety concerns, if any, associated with its use. It is the other. Its unit of measure is the reciprocal second (sec-1).
responsibility of the user of this standard to establish appro- 3.1.5 shear stress, n—the force per unit area required to
priate safety and health practices and determine the applica- produce the shearing action. Its SI unit of measurement is the
bility of regulatory limitations prior to use. See 10.6 for pascal, and its cgs unit of measurement is dynes/cm2.
specific precautionary information.
3.1.6 viscosity, n—the ratio between the applied shear stress
2. Referenced Documents and the rate of shear is called the coefficient of viscosity. This
coefficient is a measure of the resistance to flow of the liquid.
2.1 ASTM Standards:2 The SI unit of viscosity is the pascal second (Pa·s). The
E644 Test Methods for Testing Industrial Resistance Ther- centimetre gram second (cgs) unit of viscosity is the poise
mometers (dyne·s/cm2) and is equivalent to 0.1 Pa·s. Frequently, centi-
E1137 Specification for Industrial Platinum Resistance Ther- poise (cP)—equal to one millipascal second (mPa·s)—is used
mometers as the viscosity unit.
3. Terminology 3.2 Definitions of Terms Specific to This Standard:
3.2.1 apparatus-measuring geometry, n—the part of the
3.1 Definitions:
equipment that is immersed in the asphalt sample, the dimen-
3.1.1 apparent viscosity, n—the ratio of shear stress to shear
sions of which are used, in conjunction with the rotational
rate for a Newtonian or non-Newtonian liquid.
resisting torque, to calculate the apparent viscosity. This
geometry may be referred to by the equipment manufacturer as
a spindle, bob, inner concentric cylinder, vane, and so forth.
1
This test method is under the jurisdiction of ASTM Committee D08 on Roofing
and Waterproofing and is the direct responsibility of Subcommittee D08.03 on
Surfacing and Bituminous Materials for Membrane Waterproofing and Built-up 4. Summary of Test Method
Roofing.
Current edition approved July 1, 2012. Published August 2012. Originally 4.1 A rotational viscometer, as described in this test method,
approved in 1984. Last previous edition approved in 2006 as D4402 – 06. DOI: is used to measure the apparent viscosity of asphalt at elevated
10.1520/D4402_D4402M-12.
2
temperatures. The torque on the apparatus-measuring geom-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
etry, rotating in a thermostatically controlled sample holder
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 containing a sample of asphalt, is used to measure the relative
the ASTM website. resistance to rotation. The torque and speed are used to

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 D4402/D4402M − 12
determine the viscosity of the asphalt in pascal seconds, 9.2 The accuracy of the viscometer shall be checked at least
millipascal seconds, or centipoise. annually using a certified reference fluid of known viscosity at
various temperatures, using the method described by the
5. Significance and Use supplier of the reference fluid. The reference fluid shall be
5.1 This test method is used to measure the apparent certified to be Newtonian in behavior over the full range of
viscosity of asphalts at handling, mixing, or application tem- expected test temperatures and shear rates. The reference fluid
peratures. shall be certified at a temperature within 50°C [90°F] of the
5.2 Some asphalts may exhibit non-Newtonian behavior temperature(s) to be used during the test. The viscosity
under the conditions of this test method, or at temperatures measured shall be within 62 % of the certified value, or the
within the range of this test method. Since non-Newtonian viscometer requires recalibration.
viscosity values are not absolute properties, but reflect the 9.3 The accuracy of the temperature reading and the tem-
behavior of the fluid within the particular measurement system, perature stability of the temperature controller are to be
it should be recognized that measurements made by this test checked at least every six months by placing an asphalt sample
method may not always predict field performance under the or high flash point oil in the test chamber, and equilibrating to
conditions of use. a temperature within 50°C [90°F] of the temperature(s) to be
5.3 Comparisons between non-Newtonian viscosity values used during the test. The sample temperature shall then be
should be made only for measurements made with similar measured to within 60.1°C [60.2°F] by using a NIST trace-
conditions of temperature, shear rate, and shear history. able measuring device, as described in Test Methods E644. If
any temperature differential is indicated, the set point of the
6. Apparatus temperature controller shall be offset accordingly.
6.1 Rotational Viscometer, capable of measuring the torque
required to rotate the selected apparatus-measuring geometry at 10. Procedure
a selected constant speed while submerged in asphalt at 10.1 Follow the manufacturer’s instructions for the opera-
constant desired test temperature, and with the capability to tion of the instrument.
convert the torque measurement to viscosity in pascal seconds, 10.2 Allow the instrument electronics to warm up for at
millipascal seconds, or centipoise. This calculation may need least five minutes before conducting any calibrations or analy-
to be done manually for some instruments. ses.
6.2 Apparatus-measuring geometry, of various shapes and 10.3 Set the temperature controller to the desired test
sizes, for measurement of various viscosities of asphalt. temperature, taking into account any offset determined in 9.3.
6.3 Temperature-Controlled Thermal Chamber Heater, for 10.4 Select an apparatus-measuring geometry that will de-
maintaining the sample of asphalt at the test temperature. velop a resisting torque between 10 and 98 % of the instrument
6.4 Sample Chambers, reusable or disposable. capacity at the selected speed. Generally, measurements will be
6.5 Temperature Controller, capable of maintaining the more accurate at higher torque readings.
specimen temperatures to 61.0°C [62.0°F] for test tempera- 10.5 Preferably, preheat the sample chamber and the se-
tures between 38 and 260°C [100 to 500°F]. lected apparatus-measuring geometry until temperature equi-
6.6 Balance, readable to 0.1 g, for determining the mass of librium has been obtained for at least 15 min. If filled asphalts
asphalt sample. are being measured, this step is mandatory.
6.7 Platinum Resistance Thermometer (PRT), with a probe 10.6 Add the volume of sample specified by the manufac-
which conforms to the requirements of Specification E1137. turer for the apparatus-measuring geometry to be used to the
The PRT shall have a 3- or 4-wire connection configuration and sample chamber. A convenient way for measuring the volume
overall sheath length shall be at least 50 mm [2 in.] greater than is by weighing out the amount calculated from approximate
the immersion depth. Calibrate the PRT system (probe and density data for the sample and then returning the sample
readout) in accordance with Test Methods E644. chamber to the temperature controlled chamber heater. Thor-
oughly stir filled asphalts to obtain a representative sample
7. Reagents and Materials before weighing.
NOTE 1—Exercise caution to avoid sample overheating, and to avoid
7.1 Solvents for cleaning sample chamber, apparatus- the ignition of samples with low flash points.
measuring geometry, and accessories.
10.7 Do not overfill the sample chamber, but ensure that the
8. Preparation of Apparatus measuring portion of the apparatus-measuring geometry will
8.1 The rotational viscometer and thermal chamber heater be completely immersed. Follow the manufacturer’s instruc-
shall be leveled and prepared as recommended by the instru- tions. The sample volume is critical to meet the system
ment manufacturer. calibration standard.
10.8 Insert the selected preheated apparatus-measuring ge-
9. Calibration and Standardization ometry into the liquid in the chamber, and couple it to the
9.1 The viscometer shall be zeroed before use, or as needed, viscometer, following the manufacturer’s instructions for
or both, according to the manufacturer’s instructions. proper alignment.

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 D4402/D4402M − 12
10.9 Bring the asphalt sample to the desired temperature 13.1.1 Single-Operator Precision (Repeatability)—
within 30 min and allow it to equilibrate at the desired test Duplicate values by the same operator using the same test
temperature for a minimum of 10 min before beginning the equipment, in the shortest practical period of time shall be
measurement. In the case of filled asphalts, start the motor considered not equivalent if the difference in the two results,
rotation immediately. expressed as a percent of their mean, exceeds 3.5 %.
10.10 Start the motor rotation of the viscometer at a speed 13.1.2 Multilaboratory Precision (Reproducibility)—The
that will develop a resisting torque that is between 10 and 98 % values reported by each of two laboratories, representing the
of the full-scale instrument capacity. Maintain this speed and arithmetic average of duplicate determinations, shall be con-
allow the sample to equilibrate for an additional 5 min. sidered not equivalent if they differ by more than 14.5 %.
Temperature should not deviate more than 61.0°C [62.0°F] 13.2 Filled Roofing Asphalt—An interlaboratory study was
during this conditioning period. conducted in 2004 comparing three filled roofing asphalts from
10.11 Measure either the viscosity or the torque at 1-min three different suppliers, tested in triplicate at 205°C [400°F]
intervals for a total of three minutes. The instrument may by nine different laboratories. The data was used to calculate
perform this measurement automatically. precision estimates for filled asphalt. The following criteria
shall be used for judging the acceptability of any result (95 %
10.12 Repeat steps 10.9-10.11 for each test temperature confidence level).
required. If filled asphalts are being measured, a new, freshly 13.2.1 The single-operator precision (repeatability) standard
stirred sample will be required for each test temperature. deviation has been determined to be 21.0 %. Therefore, two
10.13 If torque readings are above 98 % of the instrument results obtained in the same laboratory, by the same operator
capacity at the lowest test temperature, decrease the speed of using the same equipment, in the shortest practical period of
rotation of the apparatus-measuring geometry and continue time, should be considered not equivalent if the difference in
with the test, or repeat steps 10.5-10.11 with a smaller diameter the two results, expressed as a percent of their mean, exceeds
geometry and the appropriate volume of sample. 59.4 %.
10.14 If the torque reading is below 10 % of the instrument 13.2.2 The multilaboratory precision (reproducibility) stan-
capacity at the highest test temperature, increase the speed of dard deviation has been determined to be 33.2 %. Therefore,
rotation of the apparatus geometry, or repeat steps 10.5-10.11 two results submitted by two different operators testing the
with a larger diameter geometry and the appropriate volume of same material in different laboratories shall be considered not
sample. equivalent if the difference in the two results, expressed as a
percent of their mean, exceeds 94.0 %.
10.15 If the instrument does not read out directly in viscos-
ity units, multiply the torque readings by the appropriate factor 13.3 Unfilled Paving Asphalt—The precision estimates
to obtain the viscosity values. given are based on the analysis of test results from eight pairs
of AMRL proficiency samples. The data analyzed consisted of
11. Calculation results from 142 to 202 laboratories for each of the eight pairs
11.1 If the instrument does not automatically average three of samples. The details of this analysis are in NCHRP Final
readings, then calculate the result as the arithmetic average of Report, NCHRP Project No. 9-26, Phase 3. The following
the three readings taken at 1-min intervals, rounded to three criteria shall be used for judging the acceptability of any result
significant figures. If the rotational viscometer has a digital (95 % confidence level).
output displaying viscosity in centipoise (cP), multiply by 13.3.1 The single-operator precision (repeatability) coeffi-
0.001 to obtain the viscosity in pascal seconds (Pa·s). For cient of variation (1s %) has been determined to be 1.2 %.
instruments that offer automation, the results of a 3-min Therefore, two results obtained in the same laboratory, by the
integration shall be acceptable. same operator using the same equipment, in the shortest
practical period of time, should be considered not equivalent if
12. Report the difference in the two results, expressed as a percent of their
12.1 Report test temperature, apparatus-measuring geom- mean, exceeds 3.5 % (d2s %).
etry type and size, torque in mNm or percent of instrument 13.3.2 The multilaboratory precision (reproducibility) coef-
capacity, and speed in sec-1 or r/min with viscosity results in ficient of variation (1s %) has been determined to be 4.3 %.
pascal seconds (Pa·s), millipascal seconds (mPa·s), or centi- Therefore, two results submitted by two different operators
poise (cP). For example, Viscosity at 135°C = 0.455 Pa·s with testing the same material in different laboratories shall be
Bohlin 25 mm bob, 8.3 mNm of torque at 10 sec-1 or Viscosity considered not equivalent if the difference in the two results,
at 400°F = 240 cP with Brookfield spindle number 31, 48 % expressed as a percent of their mean, exceeds 12.1 % (d2s %).
torque at 60 r/min. 13.4 Bias—No information can be presented on the bias of
this test method for measuring apparent viscosity because no
13. Precision and Bias material having an accepted reference value is available.
13.1 Unfilled Roofing Asphalt—The following criteria shall
be used for judging the acceptability of any result (95 % 14. Keywords
confidence level). 14.1 asphalt; rotational viscometer; viscosity

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 D4402/D4402M − 12
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