Implementation of the aashto m 332 specification: A case study

Over the past 20 years, changes in asphalt binders, the widespread adoption of polymer modified asphalts, and the need to bump asphalt binder grades to consider traffic conditions have exposed the gaps in the AASHTO M 320 specification, and subsequently led to the AASHTO M 332 specification. The State of Arizona initiated an experimental study to explore the possibility of adopting AASHTO M 332 into its binder specifications. In this paper, the specific challenges, technical implications of some key differences in the current Arizona standard compared with the AASHTO M 332 standard, and the approach taken to overcome the differences are explored and documented. Some of the key issues include the shortcomings of the Jnr difference parameter, uncertainty of the pressurized aging vessel (PAV) temperature to be used, effect on the intermediate temperature parameter, |G*|sind, and the prospective distribution of asphalt binder grades if the new specification is adopted. Overall, the AASHTO M 332 specification is promising for the State of Arizona with minor changes recommended to prevent changes in binder formulations and influx of asphalt binders inferior to those currently available.