Short and Long-Term Aging Methods to Accurately Reflect Binder Aging in Different Asphalt Applications

Asphalt binder experiences aging during mixture production and service life of the pavement. Aging of asphalt binder directly influences the stiffness and damage resistance of asphalt mixtures. The current industry practice is to simulate short-term and long-term aging in asphalt binders using the rolling thin-film oven and pressure aging vessel, respectively. These methods and the parameters (e.g., temperature, pressure, and duration) involved in the use of these methods were developed a few decades ago and adopted as standards primarily to aid performance grading of asphalt binders. Over the last few years, there have been several changes in asphalt technology. For example, the use of warm mix asphalt (WMA) and reclaimed asphalt pavements has significantly increased. The use of additives, chemical and/or polymer modifiers to enhance binder properties, has also significantly increased; in some cases, the oxidation kinetics of such modified binders are significantly different from conventional binders. Finally, several studies have also shown that a better understanding of binder oxidation can improve our ability to predict damage in asphalt pavements. In light of the above advances, there is a need to revisit the methods that are currently used to age asphalt binders in the laboratory with the expectation that this aging reflects short-term and long-term aging of binders that occurs in the field. The objective of this research is to develop laboratory aging methods to accurately simulate the short-term (from production to placement) and long-term (in-service) aging of asphalt binders. The research may involve investigating the relationship between different methods of laboratory aging of asphalt binders and the actual aging that occurs during mixture production, transport, and placement as well as during the service life of the pavement structure. Accomplishment of the project objective will require at least the following tasks: (1)Review the available methods for accelerated aging of asphalt binders and the feasibility of using such methods in terms of any additional capital cost, staff skill, time required, throughput, and minimum sample size. (2) Conduct laboratory and field testing to establish relationships between parameters associated with the laboratory method (e.g., aging temperature, duration, etc.) to the actual aging of asphalt binders considering factors related to the following, at a minimum: material type (e.g., polymer-modified binders, binders containing ground tire rubber, and binders recovered from emulsions); production type (e.g., binders used in the production of hot mix asphalt (HMA) or WMA with chemical agents or foaming); storage and transportation conditions during production (e.g., storage in silos for extensive durations of time or during long hauls); mixture type and in-service conditions (e.g., dense graded versus open graded mixes, and climatic conditions at the pavement location); and aggregate type that is in contact with the binder in the asphalt mixture (e.g., aggregate with typical surface mineralogies and specific surface areas). (3) Identify the best possible aging method(s) and parameter(s) that can be used to simulate different aging conditions for asphalt binders. Such a method and concomitant parameters may be based on an existing method, a variation of an existing method, or a new method. (4) Propose an implementation plan for the use of the proposed aging method and parameters so that it can be (i) phased into the existing framework of binder specifications and (ii) used to characterize the aging kinetics of asphalt binders as needed. (5) Propose a standard method for short- and long-term aging of asphalt binder in American Association of State Highway and Transportation Officials (AASHTO) format for submission to the AASHTO Subcommittee on Materials.


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Filing Info

  • Accession Number: 01598912
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: 09-61
  • Files: TRB, RiP
  • Created Date: May 8 2016 1:00AM