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Field Performance of Asphalt Pavements at Low and Intermediate Temperatures

Within its current practice, state transportation agencies are using aggressive rutting and stripping testing to qualify asphalt mixes for use in highway construction. This practice was in response to the typical distresses found in pavements from the late 1980s and early 1990s. In most states, this has generally resolved rutting issues, but has led to a detrimental effect on cracking and raveling behavior in the pavements. This one-dimensional approach has been recognized as a challenge to be addressed within the mix design process and highway agencies have been looking for practical tests to provide a performance balance and increase mix durability. Asphalt mixes now contain Recycled Asphalt Pavement (RAP) and less asphalt binder, both virgin and total, in an attempt to resist rutting and save on materials. Furthermore, with the high cost of asphalt binder and the increase in available substitutes and modifiers, asphalt binder testing alone is no longer adequate to predict pavement performance thus mix performance testing at all temperatures is becoming increasingly important. Building a mix to avoid both rutting and cracking requires a balance of priorities because these behaviors are often in direct conflict with each other. However, in the absence of practical tests, mix design and acceptance programs currently favors rutting resistance, leaving a clear imbalance and skewed performance. As the practice continues, these effects are becoming more pronounced; should current practices continue without adjustment for durability performance, constructed pavements will continue to exhibit early age cracking (both thermal and fatigue) and the performance of the pavements will be significantly affected, leading to a significant loss of investment by highway agencies. A new test to evaluate low temperature performance of asphalt mixtures was developed with previous funding assistance from the MPC. This test uses the existing Bending Beam Rheometer (BBR) to test asphalt mixes. Test protocols were created for both cores and laboratory compacted samples and the relation to pavement performance was determined. This test was voted as an AASHTO provisional specification (TP-125) and could soon be adopted as a requirement for asphalt mix design. In a parallel effort, the Semi-Circular Bending/Fracture Energy test (SCB) was determined as a feasible test for intermediate temperature performance and was also voted as an AASHTO provisional specification (TP-126). By using these two tests (BBR and SCB) mixes can be evaluated for cracking potential in regards to RAP content, asphalt binder content, binder modification, etc., resulting in a complete performance-related specification. However, adoption of any pavement performance specification requires an understanding of ALL aspects of mixture design including factors like: How will the new requirement affect the binder content? How will the new requirement affect the durability of asphalt pavements? How will the requirement affect current rutting tests (i.e., Hamburg WTD results)? How do all of these tests complement each other? This research will attempt to answer these questions by evaluating selected asphalt mixtures for low temperature cracking, intermediate temperature fracture energy, and high temperature deformation (rutting) to ensure that the addition of a low temperature test will not affect the high temperature performance or the durability of pavements. This work will allow for better optimization of mixes and reduction of poor performance potential of highway assets. Therefore, this work will have relevance at a regional and national level.

Language

  • English

Project

  • Status: Active
  • Funding: $180000
  • Contract Numbers:

    69A3551747108

  • Sponsor Organizations:

    Office of the Assistant Secretary for Research and Technology

    University Transportation Centers Program
    Department of Transportation
    Washington, DC  United States  20590
  • Project Managers:

    Kline, Robin

  • Performing Organizations:

    University of Utah, Salt Lake City

    College of Engineering, Department of Civil Engineering
    Salt Lake City, UT  United States  84112-0561
  • Principal Investigators:

    Romero, Pedro

  • Start Date: 20171115
  • Expected Completion Date: 20220731
  • Actual Completion Date: 0
  • Source Data: MPC-546

Subject/Index Terms

Filing Info

  • Accession Number: 01651464
  • Record Type: Research project
  • Source Agency: Mountain-Plains Consortium
  • Contract Numbers: 69A3551747108
  • Files: UTC, RiP
  • Created Date: Nov 24 2017 1:27PM