Topic: Environment

Researchers in Hawaii are turning discarded fishing nets and household plastic waste into asphalt for roads. This innovative solution could help reduce environmental impacts and provide a new destination for plastics.

Hawaii faces a growing problem with plastic waste. Recycling is expensive and difficult, and large amounts of marine debris continue to wash ashore or remain in surrounding waters. To tackle this issue, researchers are exploring an innovative solution by turning discarded fishing nets and household plastic waste into asphalt for roads.

Early results suggest that the approach could provide a practical new destination for plastics that might otherwise end up in landfills or the ocean. Jeremy Axworthy, a researcher at the Center for Marine Debris Research (CMDR) at Hawaiʻi Pacific University, presented the findings at the spring meeting of the American Chemical Society (ACS).

Since 2020, most roads in Hawaii have been built using polymer-modified asphalt (PMA), which is designed to improve strength and durability. Researchers wondered whether some of the virgin polymer could be replaced with discarded plastics.

To make PMA, pellets of styrene-butadiene-styrene (SBS) are melted into a sticky petroleum-based asphalt binder. That binder is then mixed with heated aggregates (rocks and sand), coating the material before it is laid as pavement.

Researchers partnered with environmental chemist Jennifer Lynch, director of CMDR and leader of the research team. They collected abandoned fishing nets from Hawaii's waters for use in experimental recycled plastic asphalt.

A local paving company resurfaced sections of a residential street on Oahu using three different asphalt mixtures: one with standard SBS, one containing recycled polyethylene from Honolulu's residential recycling program, and one made with polyethylene recovered from discarded fishing nets.

About 11 months later, Lynch's team returned to collect road dust from each section so they could measure any microplastic released into the surrounding environment.

Why It Matters

This innovative solution can help reduce plastic waste in our oceans and provide a new destination for plastics. It also shows how science can be used to solve real-world problems.

Key Facts

• Hawaii is facing a growing problem with plastic waste, including discarded fishing nets and household plastic waste.
• Researchers are exploring an innovative solution by turning these plastics into asphalt for roads.
• The approach could provide a practical new destination for plastics that might otherwise end up in landfills or the ocean.
• Polymer-modified asphalt (PMA) is used to make roads in Hawaii, and researchers wondered whether some of the virgin polymer could be replaced with discarded plastics.
• A local paving company resurfaced sections of a residential street on Oahu using three different asphalt mixtures: one with standard SBS, one containing recycled polyethylene from Honolulu's residential recycling program, and one made with polyethylene recovered from discarded fishing nets.

Key Terms

Polymer-modified asphalt (PMA)

A type of asphalt designed to improve strength and durability

Implications

This innovative solution can help reduce plastic waste in our oceans and provide a new destination for plastics. It also shows how science can be used to solve real-world problems.