Implementation of Polyphosphoric Acid Modification of Asphalt Binders and Related Experience: Case Study

This paper provides a case study demonstrating how a regional asphalt supplier located in Glendale, Arizona, implemented polyphosphoric acid (PPA) as an asphalt modifier. This modification approach was necessitated by a change in asphalt binder selection strategy on the part of the Arizona Department of Transportation. The paper outlines why the supplier decided to use PPA, experimentation that validated its use, and operational and modification tactics. Pavement performance of seven projects that utilized PPA-modified binders is described. Typical quality control data of unmodified and PPA-modified binders are included.