Each year in the United States, millions of tons of plastic waste are discarded and not recycled, leading to serious environmental problems. In an effort to help keep this waste from ending up in the environment, engineers at the University of Missouri are partnering with Dow and the Missouri Department of Transportation (MoDOT) to test mixing plastic waste into the asphalt pavement mixtures for possible use on American roadways and bridges.
Asphalt pavement mixtures are typically created from a mixture of asphalt and other materials called “aggregates,” such as stone, sand or gravel, said Bill Buttlar, the Glen Barton Chair in Flexible Pavements in the Department of Civil and Environmental Engineering. He said the chemical makeup of plastic helps it become a good product for road pavement mixtures.
“Plastic was developed to be durable and has a shelf life of hundreds of years,” Buttlar said. “Asphalt and plastics are also chemically similar because they both come from crude oil, so they can be mixed together. They aren’t perfectly compatible, but it’s close enough that engineers and chemists can work together to find a workable solution.”
Inside the Mizzou Asphalt Pavement and Innovation Lab, or MAPIL, located in the MU College of Engineering, engineers and students are determining how to incorporate various types of single-use, polyethylene-based plastic waste into asphalt pavement, including drinking bottles, grocery bags and drinking straws. Buttlar, the lab’s director, said the idea for using plastic waste in pavement developed through a series of conversations he had with Mizzou alumnus Jim Fitterling, the chairman and CEO of Dow, a $39 billion global materials science company, following a tour Fitterling had of the MAPIL lab during a recent visit to the college.
Fitterling is looking forward to partnering with his alma mater. “I joined Dow more than 35 years ago, two weeks after graduating from Mizzou,” Fitterling said. “Both this company and this university have been integral parts of my life. So, I always appreciate the opportunity to bring the two together. But, even more than that, through this project, Mizzou and Dow are partnering on an innovative solution that will better our planet. This project fits perfectly at the intersection between both Dow and the University of Missouri’s purpose and mission. At Dow, we’re working to tackle some of the toughest challenges facing our world, like ending plastic waste. These challenges will require great problem solvers and strong partnerships. I know we’re getting both when we work with the University of Missouri College of Engineering.”
MoDOT is excited to begin seeing the use of recycled plastic in asphalt pavements, said Dave Ahlvers, state construction and materials engineer. “Recycled material is an important element of delivering a durable and economic product,” Ahlvers said. “We currently utilize recycled asphalt, pavement, recycled asphalt shingles and ground tire rubber in our mixtures. Expanding to utilize plastic reduces the amount of virgin material needed, which is a winning situation for the environment and overall cost.”