scope:

This test method covers the determination of the low-temperature performance grade (i.e., minimum design pavement temperature) of asphalt binders by means of a bending beam rheometer after going through a physical aging (physical hardening) process. It is applicable to material having a flexural stiffness value from 20 MPa to 1 GPa (creep compliance values in the range of 50 nPa-1 to 1 nPa-1) and can be used with material aged using T 240 (RTFO) or R 28 (PAV) or with recovered asphalt binder. The test apparatus is designed for testing within the temperature range from -36 to 0°C.

The bending beam rheometer method used in T 313 conditions samples for 1 h and tests at a temperature 10°C warmer than the low-temperature performance grade to determine if the asphalt binder passes the low-temperature requirement. This standard requires testing at two temperatures, to determine by extrapolation a limiting temperature for each of the three conditioning times and two conditioning temperatures.

Low-temperature physical aging of asphalt varies as a function of temperature and time. This standard conditions at 10°C and 20°C warmer than the low-temperature performance grade for periods of 1 h, 24 h, and 72 h to simulate the effect of extended conditioning at two different cold temperatures.

Test results are not valid for beams of asphalt binder that deflect more than 4 mm or less than 0.08 mm when tested in accordance with this method.

The values stated in SI units are to be regarded as the standard.

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 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 R 18 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with R 18 alone does not completely assure reliable results. Reliable results depend on many factors; following the suggestions of R 18 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.