The Impacts on Pavement Performance from Changes in Asphalt Production

Since implementation of the Performance-Graded Asphalt Binder specification developed by the Strategic Highway Research Program (SHRP), petroleum refining processes have changed considerably. Increased global demand for fuels and plastics has led refiners to develop improved refining techniques which allow them to extract increased amounts of the higher value light products from crude oil. Additionally, a wider variety of crude oil sources are being used to produce asphalt than was the case when the performance-graded (PG) grading system was first developed. Other changes include processes required for production of low sulfur fuel, expanded use of polyphosphoric acid and petroleum distillates, and addition of recycled materials such as re-refined engine oil bottoms (REOB), paraffinic base oils, bio binders, and ground tire rubber. Expanded use of recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) is also driving the use of softer binder grades, which are often produced by modification of stiff binders with various additives. Although today's asphalt binders typically continue to meet the requirements of the PG specification, several highway agencies in the United States and Canada are experiencing early failures of newly constructed pavements despite general compliance with the existing and proven pavement and mix design standards, construction methods, and materials specifications. These early failures are being described as atypical raveling whereby the surface exhibits asphalt matrix loss, aggregate loss, low-temperature cracking, and instances of total surface course loss within five years. One explanation that could be contributing to these early failures is the observed decrease in quality of asphalts. Anecdotal evidence from agency and contractor personnel suggests the asphalt does not adhere to the equipment as it did in the past. Simply put, the asphalts are not as sticky as they used to be. Given that there has been and continues to be significant change in the production and formulation of asphalt binders, it is a challenge for materials specifications to remain current. Accepted terms such as "neat" asphalt and "modifier" apparently have evolved as well with little understanding by the departments of transportation (DOTs) as to the implications. Initial success with the SHRP model and the overall evolution of asphalt binder suggests that current asphalt binder properties and binder specifications are worthy of comprehensive review. The nationwide investment in pavements is in the billions of dollars. Some agencies are experiencing reductions in expected pavement life of fifty percent or more, requiring earlier application of pavement preservation or rehabilitation treatments. Considering the reduced funding levels for highway agencies, coupled with increased costs of asphalt pavements, these reductions in pavement life will make it extremely challenging to meet the performance measures required under Moving Ahead for Progress in the 21st Century (MAP-21). Current research efforts are focused on binder testing and mix designs, with a view towards complementing the original SHRP model with its iterative improvements. Binder tests such as the bending beam rheometer with extended conditioning and notched tension testing are being evaluated as potential tools to evaluate binder performance. This research is focused on the risk assessment of the existing PG binder specification to fully assess performance characteristics of new asphalt binders prior to use in pavement construction. The results of this study will have an immediate impact on the ability of highway agencies to achieve expected pavement life. The objective of this research is to identify potential shortcomings in the current PG asphalt binder specifications that are leading to incidents of premature failure of asphalt pavements and propose changes to improve those specifications. Specific tasks to accomplish this objective include: (1) identify changes in crude oil refining related to asphalt binder production that have occurred since 1996, including the use of additives such as REOB and paraffinic base oils; (2) investigate incidents of premature asphalt pavement failure occurring in several states and provinces since the mid-2000s and identify the principal failure mechanisms; (3) evaluate the correlation between major changes in oil refining and energy market demands and occurrences of premature pavement failure; (4) compare the physical and chemical properties of current asphalt binders with binders from different periods, such as samples analyzed by the Asphalt Research Consortium, or through recovery from field samples or from stockpiled reference samples such as those collected by the Federal Highway Administration (FHWA) Materials Reference Library or Long Term Pavement Performance program; (5) identify gaps in the existing PG binder specification that may be leading to use of binders that contribute to early pavement failure; (6) evaluate current and proposed asphalt binder tests to determine how well their results correlate with actual pavement performance and develop proposed changes to the American Association of State Highway and Transportation Officials (AASHTO) PG binder specification and test methods, with emphasis on tests for low-temperature performance and asphalt adhesion quality.


  • English


  • Status: Proposed
  • Contract Numbers:

    Project 09-60

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway & Transportation Officials

    444 North Capitol Street, NW, Suite 225
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Harrigan, Edward

  • Start Date: 20150805
  • Expected Completion Date: 0
  • Actual Completion Date: 0
  • Source Data: RiP Project 40200

Subject/Index Terms

Filing Info

  • Accession Number: 01572350
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 09-60
  • Files: TRB, RiP
  • Created Date: Aug 6 2015 1:00AM