Instead of building a road entirely from plastic, engineers mixed recycled plastic into a conventional asphalt mixture.
Hawaii transportation officials began a road project in 2022 by mixing recycled plastic into asphalt, a type of concrete. The project used recycled plastic equal to nearly 195,000 plastic bottles that could otherwise have become waste, according to Khon2 News.
The Hawaii Department of Transportation (HDOT), in partnership with the University of Hawaii at Manoa and other organisations, launched the pilot project on Oahu to test how the material would perform when used in a road. Work began on October 11, 2022, along Fort Weaver Road near Pu’uloa Beach Park in Ewa Beach.
The project called for approximately 1,950 tons of plastic-modified asphalt. Instead of building a road entirely from plastic, engineers mixed recycled plastic into a conventional asphalt mixture. Officials wanted to find out whether the material could produce a road that performed as well as or potentially better than the pavement already used in Hawaii, according to University of Hawaii News.
The use of plastic in the road also led researchers to study what would happen to the material as vehicles repeatedly drove over it. Researchers from the University of Hawaii at Manoa’s College of Engineering evaluated the pavement over 18 months. They studied its performance and investigated its potential to release microplastics into the surrounding environment.
Professor Adrian Ricardo Archilla from the university’s Department of Civil and Environmental Engineering explained that researchers wanted to see whether recycled material could be incorporated without reducing the road’s performance.
To compare the experimental road with another surface, researchers installed a control section using polymer-modified asphalt alongside the plastic-containing road.
This allowed them to compare how the different surfaces performed under similar traffic and environmental conditions, according to Hawaii.gov.
The project also included plans to evaluate asphalt mixtures containing 50 per cent recycled asphalt pavement, or RAP.
The resulting data could help determine whether Hawaii could substantially increase the proportion of recycled asphalt used in future roads.
According to Khon2 News, researchers have been examining whether the road releases microplastics into the environment, and the findings so far have been encouraging. Residents living along Fort Weaver Road near Puuloa Beach Park also said the road has become noticeably smoother.
