A New Purpose for Plastic Waste
Hawaii is tackling two environmental challenges with one innovative solution: transforming discarded fishing nets and recycled plastic waste into road-building materials. Researchers at the Center for Marine Debris Research (CMDR) at Hawaiʻi Pacific University, in collaboration with the Hawaii Department of Transportation (HDOT), developed asphalt mixtures using plastic collected from the ocean and local recycling programs. The team presented the research at the American Chemical Society (ACS) Spring 2026 meeting.
The project aims to keep plastic out of overflowing landfills and the Pacific Ocean while reducing the environmental impact of shipping waste off the islands for disposal. By giving marine debris a second life, researchers hope to create a more sustainable way to manage Hawaii’s growing plastic waste problem.
From Marine Debris to Durable Pavement
Since 2020, Hawaii has widely used polymer-modified asphalt because it better resists cracking, heavy rain, and tropical weather. Instead of relying entirely on newly manufactured polymers, researchers investigated whether recycled plastics—including abandoned fishing nets made primarily from high-density polyethylene (HDPE)—could replace part of these materials.
Researchers processed recovered fishing gear and household plastic waste into pellets before blending them into asphalt. Construction crews then paved test sections of a residential road on Oahu with different asphalt mixtures, including conventional asphalt, recycled household plastic, and recycled fishing nets. These real-world trials allowed scientists to compare the performance of each material under everyday traffic conditions.
Do Plastic Roads Shed More Microplastics?
One of the biggest concerns was whether roads containing recycled plastic would release additional microplastics into the environment. Nearly a year after laying the roads, scientists collected road dust and stormwater samples for detailed chemical analysis.
The early findings showed promising results. Researchers found that roads made with recycled polyethylene did not release more plastic particles than conventional polymer-modified asphalt. They also discovered that tire wear produced the vast majority of microscopic particles found in road dust, rather than the recycled plastic embedded in the pavement. Because the plastic melts into the asphalt binder during production, any particles that wear away contain a mixture of stone, asphalt, and polymer instead of loose plastic fragments.
A Sustainable Path Forward
Although researchers continue to evaluate the long-term durability of these experimental roads, their results suggest that recycled plastics can serve as valuable construction materials without increasing microplastic pollution.
If future testing confirms these findings, Hawaii could reduce marine debris, divert more plastic waste from landfills, and build longer-lasting roads using recycled materials. The project also demonstrates how innovative engineering can transform environmental waste into practical infrastructure that benefits both communities and the planet.
