For further information see the other engineering areas, Asphalt magazine and APA websites, Asphalt Institute online store and the links page for other information related to these topic area.

We also recommend that you attend our Asphalt Academy courses at sites throughout the country to obtain expert instruction on asphalt topics.

Polyphosphoric Acid Modification of Asphalt

  • A study titled PERFORMANCE OF ASPHALT MIXTURES CONTAINING POLYPHOSPHORIC ACID was completed September, 2014 by Harold Von Quintus of Applied Research Associates.  The study was sponsored by the Asphalt Institute, Federal Highway Administration, Association of Modified Asphalt Producers, ICL Performance Products LP and Innophos, Inc.  The purpose of the investigation was compare the long-term field performance of PPA-modified mixtures to non-PPA-modified mixtures that were placed under the same conditions.  A total of 15 paired sections (PPA-modified to non-PPA-modified) from across the United States in a wide variety of climatic and traffic conditions were analyzed by comparing rut-depth, fatigue cracking, transverse cracking and raveling.  The final report of this study can be viewed here.  In summary, no significant or consistent difference in performance was identified between the PPA-modified and non-PPA-modified mixtures.


  • Workshop on PPA Modification of Asphalt Binders
    A national workshop on Polyphosphoric Acid Modification of Asphalt Binders was conducted in Minneapolis, MN on April 7-8, 2009. The workshop was jointly sponsored by the Transportation Research Board (TRB), Federal Highway Administration, Minnesota Department of Transportation, TERRA, Association of Modified Asphalt Producers, Innophos, ICL Performance Products, and the Asphalt Institute.
    View speaker presentations (both slides and webcast videos)(external link).

    The Asphalt has a publication on poloymer modification of asphalt: PPA Modification of Asphalt – IS-220.
    The TRB also plans on publishing a circular of papers from the Workshop.



Moisture Sensitivity