Bio-based patch from ASU will lead to safer travels and recreation
Asphalt is primarily known for use in roadways, but it's also used to pave playgrounds, bicycle paths, running tracks and tennis and basketball courts — all platforms for activities where breathing toxic fumes can be dangerous. Outdoor use on driveways, rooftops and parking lots, especially in the Arizona sun, also can lead to toxic fume exposure.
A team from Arizona State University, led by Associate Professor Ellie Fini in the School of Sustainable Engineering and the Built Environment (SSEBE), has developed AirDuo, a new, patent-pending asphalt binder that not only diminishes toxic fumes of the overall asphalt-surfaced area, but also increases sustainability.
But perhaps most importantly for Fini, it reduces health hazards for those exposed to asphalt-surfaced areas, especially for those performing the installation.
AirDuo's first local trial was initiated in late August as a patch in ASU's Gammage Auditorium parking lot. Frank Castro, associate director of Facility Maintenance, helped get the research out of the lab and into the parkig lot, facilitating the lab-to-market transition. On the morning of the install, the Parking and Transit Services team, led by Assistant Manager David Triana, completed the patchwork in a few hours.
Attendees of a theater production at Gammage the same night gave the patch a workout as they arrived and departed, and Castro reported to Fini the next day that the patch had “held up great.”
Fini envisions the new low-carbon, bio-based binder will ultimately be used for all asphalt paving products, not just patches.
The U.S. Department of Labor’s Occupational Safety and Health Administration notes that about a half-million workers annually are exposed to fumes from asphalt, with health effects that include headache, skin rash, fatigue, throat and eye irritation, cough and skin cancer.
Asphalt binder is the glue that holds together the stones, sand, gravel and other aggregates in asphalt pavements. The AirDuo binding mixture is composed of low-carbon, bio-based materials that are an alternative to more toxic petroleum products, also known as bitumen. Moreover, AirDuo acts as a toxicity filter for the overall product.
After the traditional blend of aggregates and binder is laid on the roadways, the stress from heat, sun, weather and traffic causes the release of breakdown products — molecules that vaporize — some of which are odorous, highly toxic or both.
“We breathe 11,000 liters of air per day,” Fini said. “But our nose isn’t smart enough to know when the air may be dangerous for our health. That new-car smell people like? That may not be good for your lungs. We run away from a smelly trash can, but the pleasant smell or fumes from certain materials can be far more toxic.”
Fini and Judith Klein-Seetharaman, a professor in both ASU’s College of Health Solutions and School of Molecular Sciences, collaborated to review literature about the health effects of various asphalt mixtures and mapped the effects on a network of biomarkers. Citing specific contaminants present in asphalt, the team discovered that all are not created equal and that different formulas have different levels of toxicity — the majority of which have not been studied comprehensively.