Predicting the future: New protocol reveals impact of aging on asphalt pavements

Every day, the number of Illinois roads in need of repair increases. Illinois Department of Transportation is shifting gears to keep up with the demands by prioritizing road maintenance.

To achieve this goal, Illinois Center for Transportation and IDOT researchers, in preparation for long-term pavement management strategies, want to understand the effect of age on pavements in their recent effort, “R27-175: Development of Long-Term Aging Protocol for Implementation of the Illinois Flexibility Index Test (I-FIT).”

The project builds on the widely spread Illinois Flexibility Index Test, which identifies asphalt mixes susceptible to cracking and failing prematurely.

Imad Al-Qadi, principal investigator and University of Illinois at Urbana-Champaign Bliss Professor of Engineering, and Thomas Zehr, Technical Review Panel chair and IDOT hot-mix asphalt implementation engineer, are leading the effort.

Here the research team takes I-FIT one step further by investigating long-term aging effects and testing asphalt surface samples at different temperatures and durations to simulate up to 10 years of wear and tear.

“The test is appropriate for mix design as well as field performance prediction considering the environmental effect,” Al-Qadi said. “The concept is to simulate two types of aging, one during mixing and construction and one during the service.”

The research paid off, with the researchers developing a protocol for long-term aging of asphalt surface mixes.

Now industry experts will be able to identify the cracking potential of asphalt pavement before paving. Notably, they will also be able to project cracking susceptibility seven to 10 years down the line.

As for the long-term benefits?

“During the design stage, we will now be able to distinguish between the mixes that are going to perform well and the ones that will crack in the field,” Al-Qadi said. “This will have a very significant impact on the economy because a significant amount is spent each year to rehabilitate cracked pavements.”

Perhaps the most exciting factor of the researchers’ development and the presented new protocol is the economic benefits for Illinoisans.

“The hope is that the traveling public should get longer-lasting pavements and, ultimately, better value for their tax dollars,” Zehr said.