Image Courtesy: Marquesa Calderon
Hawaii is testing an innovative way to tackle its growing plastic waste problem by transforming discarded fishing nets and household plastic into asphalt for roads. Early research suggests the approach could reduce landfill waste and marine pollution while creating durable pavement suited to the islands’ tropical climate.
The project is being led by researchers at the Center for Marine Debris Research (CMDR) at Hawai?i Pacific University in partnership with the Hawaii Department of Transportation (HDOT). Jeremy Axworthy presented the latest findings during the American Chemical Society’s spring meeting, where researchers explained that the goal is to reuse plastic waste already on the islands instead of shipping it elsewhere for disposal or recycling.
Since 2020, Hawaii has widely adopted polymer-modified asphalt, which uses a synthetic polymer called styrene-butadiene-styrene (SBS) to improve flexibility and resistance to cracking, rutting, and water damage. Researchers wanted to determine whether recycled plastics could replace some of the virgin polymer without sacrificing performance or increasing environmental risks.
One of the project’s primary sources of recycled material is abandoned fishing gear collected from Hawaii’s surrounding waters. CMDR’s Bounty Project, which rewards licensed commercial fishers for removing marine debris, has recovered 84 tons of derelict fishing gear from the Pacific Ocean.
After the recovered plastics were processed into materials suitable for paving, sections of a residential street on Oahu were resurfaced using three asphalt mixtures. One contained conventional SBS, another used recycled household polyethylene, and the third incorporated polyethylene recovered from discarded fishing nets.
Nearly a year later, researchers analyzed road dust from each section using advanced chemical testing to measure microplastic release. The initial results showed that roads containing recycled polyethylene did not release more polymer particles than conventional asphalt. Researchers also found that tire wear generated significantly more particles than the recycled plastics used in the pavement.
While additional long-term testing is still needed to evaluate durability, the early findings suggest recycled plastic asphalt could become a practical solution for managing waste in Hawaii. Researchers believe the technology has the potential to reduce marine debris and landfill pressure while demonstrating that plastic recycling can succeed when paired with sustainable infrastructure projects.
