A new asphalt testing method will help improve pavement quality and make roads more durable over time, not just in Texas but across the country.
The method, developed by the Texas Department of Transportation (TxDOT) and the University of Texas at Austin Center for Transportation Research, fills missing gaps in testing for asphalt binder.
The test, called the "poker chip method," models the stress that asphalt endures on a roadway to check for cracking in the material. A sample of asphalt binder in the shape and size of a poker chip is sandwiched between two plates and then pulled until the sample cracks or fails.
The method has been in development and refinement since 2016. Zahra SotoodehNia, an engineer in TxDOT's Materials and Tests Division, was a researcher at CTR during the implementation stages of the project.
"The previous testing methods were developed over 30 years ago, and they simply don't account for the wide range of modifiers used in today's asphalt binders," SotoodehNia said. "The poker chip test is highly sensitive to both the type and quality of these modifiers. That means it can better predict how long a pavement will last and how well it will resist cracking over time. Ultimately, it helps us build roads that are more durable and require less maintenance."
Asphalt binder is one of the components used to produce hot asphalt mix and seal coats — which is used in large amounts to pave and maintain the more than 200,000 mi. of TxDOT roads across the state. By improving the quality of the binder, the pavement will last longer and be less expensive to maintain over time.
"When you drive on asphalt roads, asphalt binder is quite literally the glue that's holding these roads together," said Amit Bhasin, CTR director and lead researcher on the project. "That inherent ability of the binder to resist cracking is what dictates the serviceable life of an asphalt pavement."
The method has been adopted by the American Association of State Highway and Transportation Officials (AASHTO) as the provisional standard test method to be used nationwide. TxDOT plans to specify this test in the upcoming year and will use it to check the quality of asphalt binders both before and after they are shipped to projects.
"That's a major milestone for us and it shows that Texas is leading the way in innovation and that the other 49 states see the value in this approach," SotoodehNia said. "We hope that with AASHTO's endorsement, we see more states adopting this method, which could elevate pavement performance nationwide."
(This article is reprinted courtesy of the Texas Department of Transportation.)
