Performance of Asphalt Binders Modified with Polyphosphoric Acid (PPA)

The use of phosphoric acid (PPA) is an effective way to increase the stiffness of asphalt binders. Therefore, toward improving the performance of a base binder, many suppliers (refineries) in the United States modify it with PPA. However, many transportation agencies are concerned about the performance characteristics of PPA modification. This concern is mainly due to possible negative interaction of PPA-modified asphalt binder with other mix components, such as lime, liquid anti-striping agents (ASA), and emulsions. Since PPA is a hydrophilic material and easily absorbs water, asphalt binders modified with higher percentages of PPA have a tendency to absorb water and lose strength, which is expected to result in increased moisture damage and increased rut. This study will evaluate effect of PPA modification of selected performance grade (PG) binders on their viscosity and performance grade through Superpave binder testing protocols. Effects of selected ASA and WMA (warm mix asphalt) additives on PPA-modified binders on viscosity and PG data will also be evaluated. Moreover, the rutting and moisture susceptibility of selected PPA-modified mixes will be evaluated by using Hamburg Wheel Tracking (HWT) and Tensile Strength Ratio (TSR) test data. The moisture damage potential of selected asphalt binder and aggregate systems will be estimated through the surface free energy (SFE) technique. The chemical compositions of the base and PPA-modified binders will be determined by using an Elemental Analyzer. The study is expected to help Oklahoma Department of Transportation (ODOT) formulate guidelines for PPA-modified asphalt binders. The study will generate laboratory-based performance data of PPA-modified mixes prepared with asphalt binders and aggregates from multiple sources in Oklahoma. It is expected that the study will provide valuable information to ODOT on formulating specifications for the use of PPA-modified asphalt binders in Oklahoma. To evaluate the effects of the PPA-modification, ASA and WMA additive on asphalt binder and mix properties, the following four pathways will help to achieve the overall goals of the study: (i) evaluate asphalt binder rheology; (ii) determine asphalt binder SFE for evaluation of moisture-induced damage potential; (iii) perform elemental analysis on asphalt binder; and (iv) evaluate rut and moisture-induced damage potential of asphalt mixes.


    • English


    • Status: Active
    • Contract Numbers:


      SPTC PPA Project

    • Sponsor Organizations:

      Oklahoma Department of Transportation

      200 NE 21st Street
      Oklahoma City, OK  United States  73105
    • Performing Organizations:

      University of Oklahoma, Norman

      School of Civil Engineering and Environmental Science
      202 West Boyd Street, Room 334
      Norman, OK  United States  73019

      Southern Plains Transportation Center

      University of Oklahoma
      201 Stephenson Pkwy, Suite 4200
      Norman, OK  United States  73019
    • Principal Investigators:

      Ghabchi, Rouzbeh

      Zaman, Musharraf

    • Start Date: 20141001
    • Expected Completion Date: 0
    • Actual Completion Date: 20160930
    • Source Data: RiP Project 39395

    Subject/Index Terms

    Filing Info

    • Accession Number: 01559836
    • Record Type: Research project
    • Source Agency: Southern Plains Transportation Center
    • Contract Numbers: DTRT13-G-UTC36, SPTC PPA Project
    • Files: UTC, RiP
    • Created Date: Apr 3 2015 1:00AM