Paving Hawaiian roads with recycled plastics and abandoned fishing nets
ATLANTA, March 22, 2026 — Hawaii has a plastic problem. The island state faces economic and logistical challenges in recycling plastic waste, including marine debris that lingers in its ocean waters. Researchers in Hawaii are pioneering a method to recycle the islands’ derelict fishing nets and residential plastic trash into asphalt roads. Early demonstrations show that these recycled materials may provide a viable end-of-life fate for the region’s garbage.
Jeremy Axworthy, a researcher at the Center for Marine Debris Research (CMDR) at Hawaiʻi Pacific University, will present the team’s results at the spring meeting of the American Chemical Society (ACS). ACS Spring 2026 is being held March 22-26; it features nearly 11,000 presentations on a range of science topics.
“This work investigates whether it’s responsible to use recycled plastics in Hawaii’s roads,” shares Axworthy. “By reusing plastic waste that is already in Hawaii, we can reduce the environmental and economic impacts of transporting waste plastics from the islands, incinerating it or dumping it in Hawaii’s overflowing landfills.”
Since 2020, Hawaii’s roads have predominantly been paved with polymer-modified asphalt (PMA) to increase pavement strength and durability. Compared to standard asphalt pavement, PMA pavement is more elastic and more resistant to cracking, rutting and water damage — qualities that are especially important for the state’s tropical climate. PMA pavement is made by first melting pellets of styrene-butadiene-styrene (SBS; a type of copolymer) into a sticky, petroleum-based asphalt binder. Then, the PMA binder is tumbled with heated aggregates (rocks and sand) in a mixing drum, causing the PMA binder to fully coat the aggregates.
But why not see if discarded plastics could be incorporated into asphalt pavements as an environmentally friendly disposal option? How would modified pavements made with recycled plastics perform, and would they release microplastics or associated chemicals into the environment? These are the questions the Hawaii Department of Transportation (HDOT) aimed to answer when they reached out to environmental chemist Jennifer Lynch, CMDR director and team lead.
HDOT asked Lynch’s team for two things. The first was to provide derelict fishing nets removed from Hawaii’s marine environment for the creation of recycled plastic-modified asphalt pavements. “Foreign plastic derelict fishing gear is the largest contributor of Hawaii’s marine debris problem,” shares Lynch. “To date, CMDR’s Bounty Project, which pays a financial reward to licensed commercial fishers for marine debris removal, has removed 84 tons of large, derelict fishing gear from the Pacific Ocean.”
HDOT’s second request was to measure possible microplastic shedding from pavements made with plastic waste versus that from standard SBS-modified pavement. “CMDR’s laboratory is equipped with state-of-the-art chemical instrumentation for quantifying and characterizing microplastics in environmental samples,” explains Lynch. “This capability is incredibly unique and impactful, especially when coupled to our marine debris-removal project and our mission to recycle the debris into long-term, locally necessary infrastructure products.”
Once a U.S.-based company converted the waste into products that could be incorporated into asphalt, HDOT took the experimental asphalt mixes to Hawaii’s streets. A local paving company laid down sections of a residential road on the island of Oahu with asphalt pavement containing standard SBS, repurposed polyethylene from Honolulu’s recycling containers and polyethylene from fishing nets. After about 11 months of regular traffic usage, Lynch’s team stepped in to collect road dust samples from each section of pavement to test for microplastic shedding, which could contaminate the surrounding soil.
The researchers processed the road dust using a method that separates different types of polymers from other materials in the dust, including microplastics, larger chunks of plastic and tire rubber. Using pyrolysis gas chromatography-mass spectrometry (Py-GC-MS), they identified and measured the source of the polymers: styrene and butadiene from the standard PMA, polyethylene from the plastic-waste and fishing-net PMA, and isoprene and butadiene rubber from tires.
Initial tests showed that pavements made with recycled polyethylene did not release more polymers than the control pavement made with SBS. Lynch’s team showed this was true during mechanical performance tests with pavement samples as well as in simulated stormwater collected from the experimental road sections. Microplastic-sized particles were detected, but very few of these were identified as polyethylene regardless of the pavement type tested. This is likely because the polymers are melted into the asphalt binder, meaning particles that break off are not plastic alone; they are a mixture of rock, binder and melted polymer chains.
The CMDR team is also comparing the amount of polymers shed from the pavement to the amount of polymers shed by tires in the road dust. “In our initial Py-GC-MS data,” continues Lynch, “we saw tire wear swamps the signal of polyethylene by orders of magnitude, like gigantic peaks! We had to search the weeds of the chromatogram to find signs of polyethylene.”
Additional research is needed to assess pavement durability. But the researchers are hopeful that someday, repurposing used plastics into pavement could help reduce landfill and marine debris in Hawaii.
“Some people think plastic recycling is a hoax — that it doesn’t work; it’s too challenging,” Lynch shares. “But this work demonstrates that recycling can work when society prioritizes sustainability.”
The research was funded by the Hawaii Department of Transportation.
Visit the ACS Spring 2026 program to learn more about this presentation, “Harvesting ocean plastics to pave hawaiian roads: Evaluation of microplastic and plastic additive release from asphalt incorporating recycled plastic from various waste streams,” and other science presentations.
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The American Chemical Society (ACS) is a nonprofit organization founded in 1876 and chartered by the U.S. Congress. ACS is committed to improving all lives through the transforming power of chemistry. Its mission is to advance scientific knowledge, empower a global community and champion scientific integrity, and its vision is a world built on science. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, e-books and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS Division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.
To automatically receive press releases from the American Chemical Society, contact newsroom@acs.org.
Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society. ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies.
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Title
Harvesting ocean plastics to pave hawaiian roads: Evaluation of microplastic and plastic additive release from asphalt incorporating recycled plastic from various waste streams
Abstract
Polymer modified asphalt (PMA) is used to increase strength and durability of roads. In Hawaii, PMA is typically produced using the virgin co-polymer styrene-butadiene-styrene (SBS). Recycled plastics, such as high-density polyethylene (HDPE), may also be added to asphalt serving to sequester plastic waste. In the state of Hawaii, derelict fishing gear (DFG) is a significant problem, yet it is also a source of HDPE that can be used in recycling. However, asphalt performance and the consequences of adding recycled polymers to asphalt are not well understood. In collaboration with the Hawaii Department of Transportation (HDOT) and the University of Hawaii (UH), the Center for Marine Debris Research (CMDR) are testing the feasibility of using recycled HDPE in asphalt by quantifying microplastics and plastic additives release from roads paved with asphalts made from different combinations of virgin and recycled polymers. The specific asphalt combinations being tested are: SBS (Control-PMA), DFG with and without SBS (DFG-PMA and DFG-neat), Local Waste recycled HDPE with and without SBS (LW-PMA and LW-neat), and Commercially Available, post-industrial recycled HDPE with and without SBS (CA-PMA and CA-neat). Microplastic and plastic additive release under laboratory conditions were performed using a Hamburg Wheel Tracker Test (HWTT) with water sample analyses. Field trials were conducted on a residential road on the island of Oahu, Hawaii. Road dust was swept and analyzed for microplastics by direct analysis and solvent extraction to separate bound plastic from asphalt and plastic additives by water extraction. Microplastic samples utilized pyrolysis gas chromatography mass spectrometry for analysis. Plastic additives are subjected to solid phase extraction with analysis by gas chromatography mass spectrometry. Results produced using these novel analytical methods provide guidance on the use of recycled plastics over virgin plastics in roadways. Moreover, results of this study may provide a viable end of life fate for plastic marine debris, leading to cleaner and healthier oceans.
END
Jeremy Axworthy, a researcher at the Center for Marine Debris Research (CMDR) at Hawaiʻi Pacific University, will present the team’s results at the spring meeting of the American Chemical Society (ACS). ACS Spring 2026 is being held March 22-26; it features nearly 11,000 presentations on a range of science topics.
“This work investigates whether it’s responsible to use recycled plastics in Hawaii’s roads,” shares Axworthy. “By reusing plastic waste that is already in Hawaii, we can reduce the environmental and economic impacts of transporting waste plastics from the islands, incinerating it or dumping it in Hawaii’s overflowing landfills.”
Since 2020, Hawaii’s roads have predominantly been paved with polymer-modified asphalt (PMA) to increase pavement strength and durability. Compared to standard asphalt pavement, PMA pavement is more elastic and more resistant to cracking, rutting and water damage — qualities that are especially important for the state’s tropical climate. PMA pavement is made by first melting pellets of styrene-butadiene-styrene (SBS; a type of copolymer) into a sticky, petroleum-based asphalt binder. Then, the PMA binder is tumbled with heated aggregates (rocks and sand) in a mixing drum, causing the PMA binder to fully coat the aggregates.
But why not see if discarded plastics could be incorporated into asphalt pavements as an environmentally friendly disposal option? How would modified pavements made with recycled plastics perform, and would they release microplastics or associated chemicals into the environment? These are the questions the Hawaii Department of Transportation (HDOT) aimed to answer when they reached out to environmental chemist Jennifer Lynch, CMDR director and team lead.
HDOT asked Lynch’s team for two things. The first was to provide derelict fishing nets removed from Hawaii’s marine environment for the creation of recycled plastic-modified asphalt pavements. “Foreign plastic derelict fishing gear is the largest contributor of Hawaii’s marine debris problem,” shares Lynch. “To date, CMDR’s Bounty Project, which pays a financial reward to licensed commercial fishers for marine debris removal, has removed 84 tons of large, derelict fishing gear from the Pacific Ocean.”
HDOT’s second request was to measure possible microplastic shedding from pavements made with plastic waste versus that from standard SBS-modified pavement. “CMDR’s laboratory is equipped with state-of-the-art chemical instrumentation for quantifying and characterizing microplastics in environmental samples,” explains Lynch. “This capability is incredibly unique and impactful, especially when coupled to our marine debris-removal project and our mission to recycle the debris into long-term, locally necessary infrastructure products.”
Once a U.S.-based company converted the waste into products that could be incorporated into asphalt, HDOT took the experimental asphalt mixes to Hawaii’s streets. A local paving company laid down sections of a residential road on the island of Oahu with asphalt pavement containing standard SBS, repurposed polyethylene from Honolulu’s recycling containers and polyethylene from fishing nets. After about 11 months of regular traffic usage, Lynch’s team stepped in to collect road dust samples from each section of pavement to test for microplastic shedding, which could contaminate the surrounding soil.
The researchers processed the road dust using a method that separates different types of polymers from other materials in the dust, including microplastics, larger chunks of plastic and tire rubber. Using pyrolysis gas chromatography-mass spectrometry (Py-GC-MS), they identified and measured the source of the polymers: styrene and butadiene from the standard PMA, polyethylene from the plastic-waste and fishing-net PMA, and isoprene and butadiene rubber from tires.
Initial tests showed that pavements made with recycled polyethylene did not release more polymers than the control pavement made with SBS. Lynch’s team showed this was true during mechanical performance tests with pavement samples as well as in simulated stormwater collected from the experimental road sections. Microplastic-sized particles were detected, but very few of these were identified as polyethylene regardless of the pavement type tested. This is likely because the polymers are melted into the asphalt binder, meaning particles that break off are not plastic alone; they are a mixture of rock, binder and melted polymer chains.
The CMDR team is also comparing the amount of polymers shed from the pavement to the amount of polymers shed by tires in the road dust. “In our initial Py-GC-MS data,” continues Lynch, “we saw tire wear swamps the signal of polyethylene by orders of magnitude, like gigantic peaks! We had to search the weeds of the chromatogram to find signs of polyethylene.”
Additional research is needed to assess pavement durability. But the researchers are hopeful that someday, repurposing used plastics into pavement could help reduce landfill and marine debris in Hawaii.
“Some people think plastic recycling is a hoax — that it doesn’t work; it’s too challenging,” Lynch shares. “But this work demonstrates that recycling can work when society prioritizes sustainability.”
The research was funded by the Hawaii Department of Transportation.
Visit the ACS Spring 2026 program to learn more about this presentation, “Harvesting ocean plastics to pave hawaiian roads: Evaluation of microplastic and plastic additive release from asphalt incorporating recycled plastic from various waste streams,” and other science presentations.
###
The American Chemical Society (ACS) is a nonprofit organization founded in 1876 and chartered by the U.S. Congress. ACS is committed to improving all lives through the transforming power of chemistry. Its mission is to advance scientific knowledge, empower a global community and champion scientific integrity, and its vision is a world built on science. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, e-books and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS Division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.
To automatically receive press releases from the American Chemical Society, contact newsroom@acs.org.
Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society. ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies.
Follow us: Facebook | LinkedIn | Instagram
Title
Harvesting ocean plastics to pave hawaiian roads: Evaluation of microplastic and plastic additive release from asphalt incorporating recycled plastic from various waste streams
Abstract
Polymer modified asphalt (PMA) is used to increase strength and durability of roads. In Hawaii, PMA is typically produced using the virgin co-polymer styrene-butadiene-styrene (SBS). Recycled plastics, such as high-density polyethylene (HDPE), may also be added to asphalt serving to sequester plastic waste. In the state of Hawaii, derelict fishing gear (DFG) is a significant problem, yet it is also a source of HDPE that can be used in recycling. However, asphalt performance and the consequences of adding recycled polymers to asphalt are not well understood. In collaboration with the Hawaii Department of Transportation (HDOT) and the University of Hawaii (UH), the Center for Marine Debris Research (CMDR) are testing the feasibility of using recycled HDPE in asphalt by quantifying microplastics and plastic additives release from roads paved with asphalts made from different combinations of virgin and recycled polymers. The specific asphalt combinations being tested are: SBS (Control-PMA), DFG with and without SBS (DFG-PMA and DFG-neat), Local Waste recycled HDPE with and without SBS (LW-PMA and LW-neat), and Commercially Available, post-industrial recycled HDPE with and without SBS (CA-PMA and CA-neat). Microplastic and plastic additive release under laboratory conditions were performed using a Hamburg Wheel Tracker Test (HWTT) with water sample analyses. Field trials were conducted on a residential road on the island of Oahu, Hawaii. Road dust was swept and analyzed for microplastics by direct analysis and solvent extraction to separate bound plastic from asphalt and plastic additives by water extraction. Microplastic samples utilized pyrolysis gas chromatography mass spectrometry for analysis. Plastic additives are subjected to solid phase extraction with analysis by gas chromatography mass spectrometry. Results produced using these novel analytical methods provide guidance on the use of recycled plastics over virgin plastics in roadways. Moreover, results of this study may provide a viable end of life fate for plastic marine debris, leading to cleaner and healthier oceans.
END