On a test section of a residential street on the island of Oahu, tens of thousands of meters of fishing nets retrieved from the ocean have been melted into the asphalt. Researchers at Hawaiʻi Pacific University developed a method to integrate ocean plastic and recycled polyethylene directly into road surfaces without measurable increases in microplastic release. Field measurements after eleven months are promising, and the concept could tackle two environmental problems at the same time.
A double disposal problem
Hawaii faces a dual challenge. Vast quantities of abandoned fishing gear, known as ghost nets, drift through the Pacific around the archipelago, damaging marine ecosystems and proving nearly impossible to collect economically. At the same time, tons of recycled polyethylene land in landfills every day because the infrastructure to reprocess it cheaply does not exist.
The research group at the Center for Marine Debris Research at Hawaiʻi Pacific University asked whether both could be solved together: melt ocean plastic and recycled polyethylene into road surfaces instead of burying or incinerating them.
The technique: polymers as binder additive
Conventional asphalt uses bitumen as a binder, to which polymers are added to improve durability and weather resistance. In the standard variant known as SBS asphalt (styrene-butadiene-styrene), synthetic plastics fill that role. The Hawaii team replaced this plastic component with recycled polyethylene and ground-up fishing nets. The key distinction: the plastic is fully melted into the binder and does not exist as a free particle.
This matters because one of the main concerns about plastic roads is the release of microplastics through tire abrasion and weathering. Measurements on Oahu show no elevated microplastic levels after eleven months compared to conventional SBS asphalt. The researchers, presenting at the ACS Spring Meeting 2026, noted that most microplastic particles near roads come from tire wear anyway, not from the asphalt itself.
Parallel tests on the mainland
Hawaii is not the only test site. On Interstate 155 in Missouri, nine different recycled-material combinations are being tested in road surfaces, including rubber from old car tires, polyethylene from household collection and textile fibers. The US Department of Transportation and several states are jointly funding the research. The interest is not coincidental: US roads consume around 100 million tons of bitumen annually, which could potentially absorb enormous quantities of recycled material if the technology scales.
What remains unanswered
Eleven months on a residential street is not proof of long-term performance under heavy freight traffic. The critical open questions are how plastic-modified asphalt behaves under constant truck use, whether it responds differently at extreme heat or frost, and how its lifespan compares to conventional paving. The researchers have announced longitudinal measurements over 24 months.
The economics of scale are also unresolved. Collecting ghost nets from the ocean, shredding them and incorporating them into asphalt mixes requires infrastructure that barely exists today. How cost-competitive this would be against conventional asphalt at large scale cannot yet be reliably assessed.
What comes next
Hawaiʻi Pacific University has announced plans to expand the test track on Oahu to additional road sections and publish long-term results during 2026. The Hawaii Department of Transportation is monitoring the tests. A first regular tender for plastic-modified asphalt is planned no earlier than 2028, conditional on long-term measurement outcomes.
Roads need regular renewal. Plastic accumulates daily in the ocean. That the two might fit together is not a bad hypothesis to test.