Moving Research into Practice. Increasing WMA Implementation by Leveraging the State-Of-The-Knowledge

Warm Mix Asphalt (WMA) technology and deployment were largely driven by the asphalt industry. Implementation progressed while a number of technological questions were identified for research to answer. Research was carried out at both the state and national levels as well as by private industry, and the FHWA WMA TWG was responsible for developing key research needs statements.  WMA later became a focus area for the FHWA in its Every Day Counts (EDC) initiative, which encouraged state agencies to allow WMA in their specifications and track its usage. A number of WMA technologies were developed and marketed during the mid to late 2000s. These technologies included the use of foam (water), waxes and other specialty chemicals. A large number of demonstration sections were placed in the late 2000s by many states and contractor groups and performed favorably. This resulted in the continued and more rapid acceptance of WMA as the following benefits gained more prominence: lower production temperatures, reduced emissions and reduced energy consumption, ability to extend the construction season and construction day, and additional opportunities for more uniform and higher density construction. In the 2014 construction season, over 32 percent of the asphalt mixture tonnage placed in the United States was produced with WMA technology. The National Cooperative Highway Research Program (NCHRP) conducted several major projects on WMA technology in the 2000s and 2010s. A number of states and the industry have also carried out research projects during this period. This is a considerable “body of knowledge” that answers several important technical issues associated with WMA technologies. Nonetheless, based on a review of contemporary information, there are still gaps in the knowledge of WMA technology and performance. As additive technologies have continued to change and evolve, agencies and industry are scrutinizing production and performance to freshly assess whether WMA—as well as other technologies such as polymers, RAP, RAS, and recycling agents—provides the benefits originally envisioned. Lead States have widely adopted WMA and now well over 75% of all states have a standard WMA specification rather than a special provision. However, details on how those WMA specifications affect the characteristics of the WMA that is placed on roadways is difficult to capture, and WMA represents less than half of total state departments of transportation (DOT) tonnage with some anecdotes of WMA tonnage dropping in some areas. Research is needed to identify impediments to the wider use of WMA and develop strategies to foster its expanded implementation by the state DOTs. The objective of this research is to conduct a workshop to (1) identify the barriers encountered by those state DOTs where WMA specifications remain to be implemented and proportional WMA tonnage has lagged, and (2) establish and update implementation performance indicators that better measure WMA implementation as its usage is increased nationwide.


  • English


  • Status: Active
  • Contract Numbers:

    Project 20-44(01)

  • Sponsor Organizations:

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001

    American Association of State Highway and Transportation Officials (AASHTO)

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

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Harrigan, Edward

  • Performing Organizations:

    Myers McCarthy Consulting Engineers, LLC

  • Principal Investigators:

    McCarthy, Leslie

  • Start Date: 20170126
  • Expected Completion Date: 20180331
  • Actual Completion Date: 0
  • Source Data: RiP Project 41476

Subject/Index Terms

Filing Info

  • Accession Number: 01626371
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 20-44(01)
  • Files: TRB, RiP
  • Created Date: Feb 23 2017 1:01AM