ASTM D7643-22

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Designation: D7643 − 16 D7643 − 22
Standard Practice for
Determining the Continuous Grading Temperatures and
Continuous Grades for PG Graded Asphalt Binders
This standard is issued under the fixed designation D7643; 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
1.1 This practice is used to estimate the continuous grading temperatures and continuous grade for an asphalt binder graded in
accordance with the requirements specified in Specification D6373.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of
the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations
prior to use.The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
D8 Terminology Relating to Materials for Roads and Pavements
D2872 Test Method for Effect of Heat and Air on a Moving Film of Asphalt Binder (Rolling Thin-Film Oven Test)
D3666 Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
D6373 Specification for Performance-Graded Asphalt Binder
D6521 Practice for Accelerated Aging of Asphalt Binder Using a Pressurized Aging Vessel (PAV)
D6648 Test Method for Determining the Flexural Creep Stiffness of Asphalt Binder Using the Bending Beam Rheometer (BBR)
D6723 Test Method for Determining the Fracture Properties of Asphalt Binder in Direct Tension (DT) (Withdrawn 2021)
D6816 Practice for Determining Low-Temperature Performance Grade (PG) of Asphalt Binders (Withdrawn 2021)
D7175 Test Method for Determining the Rheological Properties of Asphalt Binder Using a Dynamic Shear Rheometer
This practice is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.44 on Rheological
Tests.
Current edition approved Dec. 1, 2016June 1, 2022. Published January 2017June 2022. Originally approved in 2010. Last previous edition approved in 20102016 as
D7643 – 10.D7643 – 16. DOI: 10.1520/D7643-16.10.1520/D7643-22.
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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D7643 − 22
3. Terminology
3.1 Definitions: Definitions—Definitions for many terms common to asphalt cement and asphalt binder are found in Terminology
D8.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 continuous grade, n—a grade defined by the estimated upper and lower continuous grading temperatures.
3.2.2 continuous grading temperatures, T , n—the estimated temperatures at which the properties of an asphalt binder are equal
c
to the specification requirements given in TablesTable 1 or 2 of Specification D6373.
3.2.3 difference between estimated continuous grading temperature for S and the m-value, ΔT —determined by subtracting the
C
continuous grading temperature for the m-value from the continuous grading temperature for S.
3.2.4 PG grading temperatures, T , n—the temperatures listed in Specification D6373 used to designate the grade of a PG binder,
PG
for example, 64 °C, 22 °C, and –28 °C for a PG 64-28.
3.2.5 specification requirements, n—the limiting values given in Specification D6373 that are used to grade an asphalt binder, for
example, 1.00 kPa for G*/sinδ, 300 MPa for S, etc.
3.2.6 test temperatures, T and T , n—two PG grading temperatures, one grade apart such that the measured properties at the two
1 2
temperatures bracket the specification requirement for the property in question.
4. Summary of Practice
4.1 The continuous grading temperature for each specification requirement is determined by interpolating between test results
obtained at two adjacent specification temperatures. The two temperatures are chosen so that the test result at one temperature is
greater than the specification requirement and the test result at the other temperature is less than the specification requirement. The
upper continuous grade is determined as the lower of the two continuous grading temperatures determined for the original and
RTFOT condition (Test Methods D2872 and D7175). The intermediate continuous grade is equal to the intermediate continuous
grading temperature (Practice D6521, Test Method D7175). The lower continuous grade is determined as the higher of the
continuous grading temperatures for S and the m-value (Practice D6521, Test Method D6648).
5. Significance and Use
5.1 The continuous grading temperatures and continuous grade are used for informational purposes only and shall not be used for
the sale or purchase of asphalt binders. The continuous grading temperatures and continuous grade may be used for forensic or
research studies and when producing, blending, modifying, or otherwise evaluating asphalt binders. This guide is applicable to
Specification D6373, Tables 1 and 2.
NOTE 1—The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the
capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable
of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone does
not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar
acceptable guideline provides a means of evaluating and controlling some of those factors.
6. Procedure
6.1 Conduct tests as described below.
6.1.1 Testing When Continuous Grading Criteria Do Not Include Failure Strain (Table 1)—For each of the specification properties
(for example, G*/sinδ, S, m-value, etc.) for which a continuous grading temperature is to be determined, obtain test results at two
test temperatures, T and T , as described in 3.2.6. When the intermediate grading temperature is required, the difference between
11 2
T and T shall be 3 °C.
11 22
NOTE 2—For example, a PG 64-XX tested for G*/sinδ at 64 °C and 70 °C may give test results of 1.86 and 0.89 kPa, respectively. These results bracket
the specification requirement 1.00 kPa.
D7643 − 22
6.1.2 Testing When Continuous Grading Criteria Include Failure Strain (Table 1)—For the low temperature, obtain test results for
S and the m-value (as described in 6.1.1) and determine the strain at failure at two test temperatures, T and T , such that test
11 2
results bracket 1 %.
NOTE 3—Additional testing may be required to verify that S is between 300 and 600 MPa at the low temperature PG grade.
6.1.3 Testing When Using Table 2—For the low temperature, only perform the testing needed to determine the critical cracking
temperature.
6.2 Perform Interpolation to Determine Continuous Grading Temperatures—For each pair of test results obtained as per 6.1,
interpolate between T and T to determine the temperature at which the test results would equal the respective specification
11 22
requirement. The interpolated temperatures shall be reported as the continuous grading temperatures.
6.2.1 For the upper and intermediate continuous grading temperatures the interpolation shall be on a semi-logarithmic scale using
the following equation:
T 5 T 1 log P 2 log P T 2 T ⁄ log P 2 log P (1)
$ ~ ! ~ !%$ % $ ~ ! ~ !%
C 1 10 S 10 1 2 1 10 2 10 1
where:
T = continuous grading temperature for the specification requirement in question, °C,
C
T , T = test temperatures, °C,
1 2
P = specification requirement for property in question, and
S
P , P = test result for the specification property in question at T and T , respectively.
1 2 1 2
P , P = test result for the specification property in question at T and T , respectively.
1 2 1 2
6.2.2 For the lower continuous grading temperature the interpolation for S shall be on a semi-logarithmic scale using the following
equation:
T 5 T 1$log ~P ! 2 log ~P !%$T 2 T % ⁄ $log ~P ! 2 log ~P !% 2 10° C (2)
C 1 10 S 10 1 2 1 10 2 10 1
T 5 T 1$log ~P ! 2 log ~P !%$T 2 T % ⁄ $log ~P ! 2 log ~P !% 2 10 °C (2)
C 1 10 S 10 1 2 1 10 2 10 1
NOTE 4—For calculation purposes, T may be designated as the upper or lower temperature as long as the corresponding test result is used for P . When
11 1
using these equations, retain the negative signs for temperatures below 0 °C.
NOTE 5—Because the properties are a non-linearnonlinear function of temperature adjacent grading temperatures should always be used in Eq 1 or Eq
2. Otherwise the interpolation will give differing results.
NOTE 6—The TREND function in Excel performs linear regression and can be used to solve Eq 1 and 2. However, when using the TREND function,
arithmetic values of T and T must be used for the Ys and logarithmic values of P , P , and P must be used for the Xs. The arithmetic value of the
11 22 1 2 S
properties and specification requirement are used in the TREND function when calculating the continuous grading temperature for the m-value and failure
strain.
6.2.3 For the lower continuous grading temperature, the interpolation for the m-value shall be on an arithmetic scale using the
following equation:
T 5 T 1$P 2 P %$T 2 T % ⁄ $P 2 P % 2 10° C (3)
C 1 S 1 2 1 2 1
T 5 T 1$P 2 P %$T 2 T % ⁄ $P 2 P % 2 10 °C (3)
C 1 S 1 2 1 2 1
6.3 Determine continuous grade and ΔT as described be
...