Researchers in Hawaii are testing whether discarded fishing nets and other recycled plastics can be used in asphalt roads without increasing pollution from road wear. Findings presented at the American Chemical Society’s spring meeting showed that experimental road sections on Oahu made with recycled polyethylene did not release more polymers than standard styrene-butadiene-styrene-modified asphalt in early analysis. The work is being carried out by the Center for Marine Debris Research at Hawaiʻi Pacific University in partnership with the Hawaii Department of Transportation.
The project comes as Hawaii faces high costs for recycling and waste transport, along with persistent marine debris in its surrounding waters. Since 2020, most roads in the state have been built with polymer-modified asphalt designed to improve flexibility and resistance to cracking, rutting and water damage. Researchers examined whether some of the virgin polymer used in that material could be replaced with recycled plastics, including polyethylene from Honolulu’s residential recycling program and plastic recovered from derelict fishing gear.
To test the idea, a local paving company resurfaced sections of a residential street on Oahu using three asphalt mixtures: a standard version, one containing recycled household polyethylene and one using polyethylene recovered from abandoned fishing nets. About 11 months later, scientists collected road dust and analyzed it with pyrolysis gas chromatography-mass spectrometry to identify material from pavement and tires. They found only a very small number of polyethylene particles across pavement types, while tire wear produced a much larger signal. Jennifer Lynch, who leads the research team, said tire material outweighed the polyethylene signal by orders of magnitude in the initial data.
Supporters of the approach say the technology could provide a local use for plastic waste already in Hawaii and reduce reliance on landfill disposal, incineration or shipping waste off the islands. Lynch said derelict fishing gear is the largest contributor to Hawaii’s marine debris problem, and the Center for Marine Debris Research’s Bounty Project has removed 84 tons of large abandoned fishing gear from the Pacific Ocean. Researchers also say the early results indicate the plastic becomes integrated into the asphalt binder rather than breaking away as standalone plastic fragments.
At the same time, the team says key questions remain unresolved. The study notes that the long-term performance of recycled-plastic asphalt and the broader consequences of adding recycled polymers to roads are not yet fully understood. More testing is still needed on durability, microplastic release and plastic additives before the material’s wider use can be assessed. Researchers say that if later studies confirm the roads hold up over time, the method could offer a new end use for marine debris and other plastic waste in Hawaii.