COLUMBIA, Mo. – There’s a new type of asphalt being used on some Missouri roads and it’s helping the environment.
Instead of throwing away plastic bottles and bags into a landfill, The University of Missouri along with the Missouri Department of Transportation (MoDOT) and Dow are testing if recycled plastic waste can be mixed with asphalt.
Professor in the Mizzou Department of Civil and Environmental Engineering Bill Buttlar said asphalt pavement is normally made from crushed rock, gravel, or sand. He is heading the project of adding plastic waste into the ingredient list.
“We were the first ones to put this material out on a real road under real traffic,” Buttlar said. “The plastic or plastic waste, in this case, is chemically compatible with asphalt. They both come from crude petroleum.”
Buttlar said about two years ago, a Mizzou alumnus Jim Fitterling, CEO of Dow, asked him if he knew how to find a way to help the plastic waste problem.
“The number one thing we had to think about is how do we get the recycled materials into the asphalt,” Buttlar said.
“We can wait and put the recycled material in at the last stage, like here in Columbia at the contractor’s hot mix asphalt plant, and in that case, we can recycle large volumes of recycled material.”
The plastic waste asphalt mixture is getting a real-world test in Columbia, where MoDOT starting using it to resurface two miles of Stadium Boulevard from College Avenue east to Highway 63. More than 35,000 vehicles use that road daily.
“Just a few miles of demonstration paving, and we used over a million drinking bottles or close to 3 million plastic bags,” Buttlar said.
Buttlar said the recycled plastics are melted down into pellets and then mixed with the asphalt.
“Then when the hot rock and now dry gets to the bottom of the drum, you can mix in recycled materials like old asphalt pavement, we call that reclaimed asphalt pavement and plastic,” Buttlar said.
Some asphalt is mixers he said is made with old rubber tires from trucks and cars.
“We use the same feeder machine at the contractor’s plant to feed the plastic as we’ve been doing with rubber,” Buttlar said.
MoDOT Resident Engineer for the Columbia Project Dan Oesch said he’s happy with how this recycled asphalt is working on the roads.
“As far as the mixture itself, we did notice it was a little more tacky than the traditional mixture,” Oesch said. “The methods that we use to engineer the mixture that was placed here on Stadium, could be used on interstate routes and high-volume roads.”
Buttlar said he was meeting with MoDOT Tuesday to discuss more projects in the upcoming year like one in the bootheel of Missouri. He’s already been contacted by the state of Minnesota and France.
“This is one of our more exciting projects,” Buttlar said. “This is probably the most exciting thing we’ve ever worked on.”
He said he found similar applications in India and Southeast Asia, but those studies do not meet U.S. standards because the plastic material doesn’t reach a certain weight limit.
Buttlar went on to say asphalt normally lasts about a decade before the road needs to be resurfaced. He’s expecting this recycled asphalt mixture will last anywhere between 12 and 15 years.
Oesch said if the asphalt did last more than 10 years it would be great because all the treatment roads in Missouri receive.
“We hope to get 12 years out of it and if we got that, we would probably be just pretty good just considering the treatment we use here,” Oesch said.
Buttlar said for every 200,000 pounds of asphalt, Buttlar said it takes 200 pounds of plastic.