AASHTO PP 42-02 (2005)

This 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 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 practice can be used on data generated within the temperature range from +6°C to –36°C.

This 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 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 practice determines the critical cracking temperature for typical hot-mix asphalt (HMA), the intent of this practice is grading of asphalt binder according to AASHTO M 320, not performance prediction for asphalt pavement. This 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 visco-elasticity. 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.