Recycled plastic from garbage carts may soon be used to build asphalt roads in Texas
Those plastic milk jugs and water bottles in your recycling bin could soon be used to make pavement for roads across Texas and beyond.
Researchers at the University of Texas at Arlington are about halfway through a two-year study of how to use recycled plastic as road material. And, the Texas Department of Transportation is among the road-building agencies interested in the potential uses for the material.
The roads of the future wouldn’t be entirely plastic.
Instead, the research is focusing on using a combination of recycled plastic and traditional asphalt, which is typically made of a mix of petroleum and aggregate rocks. Plastic would make up about 10% of the paving product, the researchers said.
“This plastic road material could create a new, valuable market for plastics that are already being recycled, as well as plastic (grocery) bags which currently can’t be recycled at all,” Sahadat Hossain, a civil engineering professor, said in a phone interview.
The work by Hossain and civil engineering professor Warda Ashraf is part of a two-year, $342,588 feasibility study funded by the state transportation department.
The research comes as many cities such as Fort Worth and Arlington struggle to extend the useful lives of their landfills by reducing waste and recycling more materials. Fort Worth is on course to run out of landfill space by 2038, possibly sooner — and the city and its waste-management business partners are scrambling to find ways to get residents to recycle more of their household waste.
But the once-lucrative market for used plastics has all but dried up. Many plastic products that used to be bought for secondary purposes now wind up in landfills.
China, which once was the main purchaser of recycled plastics from the United States, beginning in 2017 stopped accepting plastics with more than 0.05% impurities. For example, if that bottle of laundry detergent you threw in the recycling bin still has a paper label glued to it, it’s no longer pure enough to resell to China as recycled plastic. Neither are the soda bottles with their gluey labels.
Impure plastics can still be recycled into building materials — the MoneyGram Park soccer facilities in Dallas include restrooms and concession stands fashioned from plastic boards — but the uses are limited. As a result, the price of recycled plastic is a fraction of what it used to be.
“When China was taking all of the recyclables, it was an $11 billion per year industry for the United States,” Hossain said in an email. “Materials that were recycled before are now going to landfills, where they are going to occupy a large volume of landfill space for a long time.”
Plastic roads have been built in other countries — India in particular has been using plastics in its pavement for decades — but have failed to gain widespread use. In the Netherlands, plastic roads and bicycle paths are already in use.
The UTA researchers say the key is to maintain a traditional mix of about 90% asphalt to 10% plastic, to ensure the roads don’t crack too easily or become too slippery for automobile tires.
“We want to make the road more sustainable with these recycled plastics mixed in,” Ashraf, an assistant professor of civil engineering with expertise in construction materials, said in an email. “The project could lead to more durable, sustainable and cheaper roads while also maintaining safety for vehicles. We also need to evaluate the effects of using recycled plastics on the performance of roads.”
Hossain said he and Ashraf also are addressing concerns that tiny bits of plastic from their road material could wind up in water supplies, as storm drainage from roads winds up in creeks, rivers and lakes. Hossain said the key is to entrap the plastic material between the aggregate rocks and the bitumen (the petroleum material in roads), so the plastic can never escape and potentially become a ”microplastic” that can get into fish or water supplies.
Texas’ transportation department isn’t yet committed to using recycled plastic on its roads, at least not on a wide scale. But the agency is encouraged by the research so far.
“The plastic road project demonstrates TxDOT’s commitment to incorporate recycling and sustainability in pavement repair, construction and management,” Boon Thian, TxDOT Dallas District pavement engineer, said in an email.
