Hawaii tests asphalt made with fishing nets and recycled plastic
Researchers found early evidence that plastic-reinforced pavement on Oahu did not shed more plastic particles than standard asphalt.
By Lucas Ferreira · Science & Environment Writer
3 min read
Hawaii researchers are testing whether discarded fishing gear and household plastic can be built into roads without adding to microplastic pollution. The work could give the islands another outlet for waste that is costly to recycle and can otherwise end up in landfills or the ocean, according to the American Chemical Society.
Jeremy Axworthy of the Center for Marine Debris Research at Hawaiʻi Pacific University presented the findings at the ACS Spring 2026 meeting. The research, funded by the Hawaii Department of Transportation, examines asphalt mixtures that use recycled plastic in place of some virgin polymer now used in road paving.
Hawaii has used polymer-modified asphalt on most roads since 2020, according to ACS. That material typically includes styrene-butadiene-styrene, or SBS, a petroleum-based copolymer added to asphalt binder to improve flexibility, durability and resistance to cracking, rutting and water damage.
The transportation department partnered with Jennifer Lynch, director of the Center for Marine Debris Research, to test whether recycled plastics could serve a similar role. The team also studied whether roads containing recycled plastic would release more microplastics or other compounds than standard SBS-modified pavement.
Fishing gear becomes road material
One part of the project used abandoned fishing nets recovered from Hawaii’s waters. Lynch said foreign derelict fishing gear is the largest contributor to the state’s marine debris problem, according to ACS.
The center’s Bounty Project pays licensed commercial fishers to remove marine debris. Lynch said the program has collected 84 tons of large derelict fishing gear from the Pacific Ocean.
After a U.S. company processed the recovered plastics for asphalt use, the project moved to a field trial on Oahu. A local paving company resurfaced sections of a residential street with three asphalt mixes: a standard SBS version, one containing recycled polyethylene from Honolulu’s residential recycling program and one using polyethylene from discarded fishing nets.
About 11 months later, researchers collected road dust from the different pavement sections. They also tested pavement performance in the laboratory and examined simulated stormwater from the experimental road sections, according to ACS.
Tire wear dominated the samples
The team separated polymers in the road dust, including microplastics, larger plastic fragments and tire rubber. Researchers used pyrolysis gas chromatography-mass spectrometry to identify chemical signatures tied to standard asphalt polymer, recycled polyethylene and vehicle tire wear.
Early results showed the pavement containing recycled polyethylene did not release more polymers than conventional SBS-modified asphalt, according to ACS. The same general pattern appeared in the lab and stormwater testing.
Researchers did find particles in the microplastic size range, but ACS said only a small number were identified as polyethylene across the pavement types. The team believes the recycled plastic becomes incorporated into the asphalt binder, so material shed by the road contains a mix of rock, binder and polymer rather than separate plastic pieces.
Lynch said the first chemical analyses showed tire wear overwhelmed the polyethylene signal by orders of magnitude. The finding points to vehicle tires as a much larger contributor to the polymer material in road dust samples from the test site.
The researchers said more work is needed to determine how well the recycled-plastic asphalt holds up over time. If durability tests support the early environmental findings, ACS said the approach could help Hawaii reduce marine debris and pressure on landfills while using waste already present in the islands.
This story draws on original reporting from ScienceDaily.