AASHTO PP 113-21

This practice provides a means of evaluating the behavior of an asphalt binder at low temperature using the results (Stiffness and m-value) from the Bending Beam Rheometer (BBR) test to calculate a value (identified as Delta Tc or Tc) that is indicative of the relaxation properties of the asphalt binder. This practice is primarily intended for use with residue generated after long-term conditioning with T 240 (Rolling Thin-Film Oven (RTFO)) and R 28 (Pressurized Aging Vessel (PAV)), but may also be used on recovered asphalt binder from asphalt mixture, reclaimed asphalt pavement (RAP), and reclaimed asphalt shingles (RAS). 

The behavior of an asphalt binder at low temperature can provide insight to the technologist indicating to what extent the asphalt binder exhibits adequate relaxation properties to minimize its contribution to non-load related cracking in an asphalt pavement.
This practice may be used in conjunction with M 320, Specification for Performance-Graded Asphalt Binder, or M 332, Performance-Graded Asphalt Binder Using the Multiple Stress Creep Recovery (MSCR) Test.