Novel approach to road surface testing earns civil engineering team ASNT top paper award
The American Society for Nondestructive Testing (ASNT) receives hundreds of paper submissions each year, and publishes those surviving a rigorous peer-review process in its journals. Out of those hundreds of submissions, only one can be crowned ASNT’s Outstanding Paper in Materials Evaluation each year, and a University of Missouri College of Engineering professor was part of the award-winning team for 2016.
The ASNT honored Bill Buttlar, the Barton Chair of Flexible Pavement Technology in the Civil and Environmental Engineering Department, and three colleagues from his former home at the University of Illinois — Megan McGovern, Nicholas Farace and Henrique Reis — for their work, receiving a plaque, medal and official recognition at the organization’s national conference.
Their paper, “Effectiveness of Rejuvenators on Aged Asphalt Concrete using Ultrasonic Non-collinear Subsurface Wave Mixing,” provided a critical breakthrough in the asphalt world. Previously, to test the state of crack resistance in the pavement surface, researchers had to carve out a sample to test, forcing a temporary shutdown of the area in question and introducing a crack into the material.
“Could you develop a procedure to assess this brittleness on the surface without taking a sample – non-destructively?” Buttlar hypothesized. “You wouldn’t have to divert traffic for very long. Better yet, by avoiding the need for coring out a road sample, you could avoid the irony of introducing a new crack source as part of your effort to deter cracking.”
Using ultrasonics, Buttlar and the research team did just that. By figuring out the precise angles through which the ultrasonic waves could be guided along the surface, they could tell the state of repair of the asphalt without taking a traditional sample.
“You can tell if the material is resistant, linear and undamaged, or if the material is becoming brittle, oxidized or the cracks are getting large, the waves will tell you that,” Buttlar said.
Using ultrasound to test the quality of the surface not only prevents researchers from having to damage the structural integrity of the road by taking a sample, it also reduces traffic delays and promotes safety; same for airport runways and taxiways. And it allows those tasked with maintaining the surfaces to quickly test new life-extending products including bio-derived rejuvenators, saving time, money and promoting environmental sustainability.
“The technology allows us to develop and to closely monitor life-extending surface treatments in field trials, thereby turning our roads into living test beds,” Buttlar said.