Researchers add plastic to asphalt for roadway experiment

COLUMBIA – The sun was setting on Stadium Boulevard, but that’s not why Dr. Bill Buttlar was there.

He was there to talk about the soil with researchers and engineers from the Missouri Department of Transportation and the University of Missouri. This could be the next big thing in road building, after all.

“It feels like. There is a lot of stir nationwide, “said Buttlar at the meeting on Monday evening.

A new asphalt mix made its debut on the stretch of road – west of US Highway 63 on Stadium Boulevard. As a product of a collaboration between MoDOT, Dow and MU’s Asphalt Pavement and Innovation Lab, asphalt differs from conventional road surfaces: it contains recycled plastic.

“Plastic was designed to be durable and have a durability of hundreds of years,” said Buttlar. “Asphalt and plastics are also chemically similar because they both come from petroleum and can therefore be mixed with one another. They’re not perfectly compatible, but it’s close enough that engineers and chemists can work together to find a workable solution. “

Buttlar said the new blend has been in the works for about two years since Jim Fitterling, CEO of Dow and MU alum, visited the lab and piqued his interest.

The idea of ​​putting plastics in asphalt was out there, but research had to start from scratch – with a “whiteboard full of ideas,” as Buttlar put it.

“We knew from literature that certain places in the world had looked at it, but it wasn’t quite operational in the United States,” he said. “And so we knew that we really had to start from scratch with research.”

Now is the time for the new asphalt mix to hit the real world.

“In Missouri, we often go from the lab to the field as quickly as possible because the ultimate evidence is … what is the field performance like under real cars and real trucks?” Said Buttlar. “This is the way we took.”

There will be three tracks with test material on Stadium Boulevard: one with traditional asphalt, one with the plastic compound and one with a compound containing scrap rubber.

The stretch of road averages 36,000 cars a day, and the researchers plan to watch the materials hold up over a year – the freezing and thawing of the Midwest requires a pavement that can withstand extreme temperatures.

Signs will mark the test sections and inform drivers, the MoDOT confirmed, although they shouldn’t notice any difference when driving over the new surface.

And no new equipment is required for the crews paving the plastic-reinforced asphalt.

“You can imagine a screw, like a large screw and a fan, which pushes the recycled material through a pipe – blowing it into the system, so to speak,” said Buttlar. “We injected other materials of similar weight, so we had a very good feeling that this would only work with existing equipment.”

Buttlar is excited to see what this new asphalt could bring to roads – and what it could keep away from landfills and oceans by recycling plastic.

“Once (people) find out about the project, they’ll be thrilled to know that when recycling comes on the side of the road, or when they put that bottle or bag in a recycling bin at work or in the mall, it really goes somewhere and could go anywhere on site, ”he said. “If we create a recycling craze, an optimism about recycling, then we can really get more of the plastic we collect and use.”

MoDOT must be attached for at least a decade, preferably 12-15 years, before replacement is required. However, recycled materials can increase the strength and toughness of a surface and provide lower cost materials for surface refurbishment projects such as Stadium Boulevard.

So in Buttlar’s eyes, asphalt mixed with plastic is a perfect way to innovate in road construction.

“That helps us to achieve the triple bottom line of economy, sustainability and longevity,” he said.

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