AASHTO R 49-09 (2022)

This standard practice covers the determination of low-temperature properties of asphalt binders using data from the bending beam rheometer (AASHTO T 313) and the direct tension tester (AASHTO T 314). This standard practice can be used on data from unaged material or from material aged using AASHTO T 240 (RTFOT), R 28 (PAV), or T 240 (RTFOT) and R 28 (PAV). This standard practice can be used on data generated within the temperature range from +6 to –36°C.

This standard practice is only valid for data on materials that fall within the scope of suitability for both test methods AASHTO T 313 and T 314.

This standard practice can be used to determine the following:

• PG Grade Determination of an Asphalt Binder—The determination of a low-temperature grade or grades that are satisfied by an asphalt binder. The determination of the temperature corresponds to the specification parameter, Tcr, the critical cracking temperature.
• Prequalification of an Asphalt Binder—The procedure required to qualify an asphalt binder for supply.
• Verification of an Asphalt Binder Grade—The testing required to certify that a binder complies with an existing prequalified binder.

While this standard practice determines the critical cracking temperature for typical hot mix asphalt (HMA), the intent of this standard practice is grading of asphalt binder according to AASHTO M 320, not performance prediction for asphalt pavement. This standard practice should not be used in lieu of AASHTO T 322.

Note—The algorithms contained in this standard require implementation by a person trained in the subject of numerical methods and viscoelasticity. However, due to the complexity of the calculations they must, of necessity, be performed on a computer. Software to perform the calculations may be written or purchased as a spreadsheet or as a stand-alone program.

This standard was formerly designated as provisional standard PP 42.