Plastic waste is difficult and expensive to manage in Hawaii, especially when it includes debris collected from the ocean. Researchers are now testing whether discardedfishing nets and household plastic can be reused in asphalt roads.
The project is still at an early stage, but it tackles two challenges at once: reducing waste and creating a local use for materials that would otherwise be transported away, incinerated, or sent to increasingly constrained landfill sites.
Roads Turned Plastic Waste Into a Solution
The idea emerged partly because Hawaii already relies on polymer-modified asphalt (PMA) for much of its road paving. Introduced to improve durability, PMA is designed to better resist cracking, rutting, and water damage in tropical conditions.
This type of asphalt is produced by blending petroleum-based binder with styrene-butadiene-styrene (SBS), a synthetic polymer used to increase flexibility. Researchers wanted to find out whether recycled plastics could replace part of that material without changing how the pavement behaves.
As Jeremy Axworthy explained during the ACS Spring 2026 presentation, the project explores whether recycled plastics can be used responsibly in Hawaii’s road system. He noted, as qoted by a BBC report, that:
“By reusing plastic waste that is already in Hawaii, we can reduce the environmental and economic impacts of transporting waste plastics from the islands, incinerating it or dumping it in Hawaii’s overflowing landfills.”
The work was launched after TheHawaii Department of Transportation (HDOT) asked the research team to evaluate both road performance and possible microplastic release.
Collected Fishing Nets Entered the Paving Mix
One source of recycled material came directly from marine cleanup operations. Jennifer Lynch, director of CMDR and environmental chemist leading the project, said abandoned fishing gear remains the largest contributor to Hawaii’s marine debris problem.
“Foreign plastic derelict fishing gear is the largest contributor of Hawaii’s marine debris problem,” stated Lynch. “To date, CMDR’s Bounty Project, which pays a financial reward to licensed commercial fishers for marine debris removal, has removed 84 tons of large, derelict fishing gear from the Pacific Ocean.”
The recovered material was then processed by a U.S. company and turned into a form that could be used to make asphalt. Test sections were laid on a residential street in Oahu. Researchers compared three different road mixes: a standard SBS-modified asphalt, one made with recycled polyethylene from Honolulu household waste, and another using polyethylene produced from recovered fishing nets.
Recycled Pavement Released No More Dust
To move beyond theory, the researchers examined what the roads actually released after being exposed to everyday traffic. After roughly 11 months, the team collected road dust from each pavement section and separated the different materials before analysis. They used pyrolysis gas chromatography mass spectrometry (Py-GC-MS) to identify the origin of the detected polymers.
Results presented at ACS showed that pavement made with recycled polyethylene didn’t release more detectable plastic material than standard pavement made with SBS. Mechanical tests and simulated stormwater experiments pointed to the same conclusion.
Microplastic-sized particles appeared in every sample, but only a small share was actually identified as polyethylene. According to Lynch, this could come down to how the pavement is produced: once the plastic is melted into the asphalt, it doesn’t separate into pure plastic pieces but stays embedded within the mix of stone and binder materials.
Another observation stood out during testing. Tire wear generated signals that were far stronger than those associated with polyethylene. Lynch said the team had to search carefully through the chromatograms to detect traces of the recycled plastic material.
“Some people think plastic recycling is a hoax, that it doesn’t work; it’s too challenging. But this work demonstrates that recycling can work when society prioritises sustainability.” she concluded.
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