Disposable face masks have protected millions of people from the COVID-19 pandemic. Once used, they are often abandoned in trash cans or left on sidewalks. But soon these masks might have a new purpose in road construction. Ashlyn DeLoughy has the details.
Faculty and students in the East Carolina University Department of Construction Management have been researching the possibility of using polymer fibers from recycled masks in hot mix asphalt used to pave roads. They have been working with S.T. Wooten and the N.C. Department of Transportation on this project since February.
The hope is that the use of these fibers will help the asphalt to resist rutting, which is the permanent deformation of pavement that can occur as a result of traffic volume, tire pressure, axial load and vehicles driving on the same areas on roadways over and over again.
Dr. George Wang, Professor at ECU and Department Chair of Construction Management, is currently leading this project.
“We noticed lots of face masks have been used each day. That’s about six to seven billions of masks around the world, that are single use masks only, which is huge pollution. But these face masks are a type of plastic.”
Wang is conducting this research alongside associate professor Dr. Carola Massarra, teaching assistant professor Dr. Jodi Farrington, teaching instructor Chelsea Buckhalter and graduate student Md. Hasibul Hasan Rahat.
“I talked to my team because only the last one or two years, plastic pollution, globally, has been brought to the attention of government, environmental news, and also researchers. So it will be a very important area for us, you know, to spend the effort to do some research.”
The team began their research process by shredding the face masks. In March, they conducted various lab tests and by early April they were adding the shredded mask material to the hot mix asphalt by .25% to 1.5% of the total weight. With paving conducted at high temperatures reaching up to 300 degrees, the plastic in the masks becomes a fluid and acts as a binding agent that hardens as it cools. This increase of polymer fiber content in the hot asphalt mix creates resistance and works to decrease rutting.
But if commercialized this asphalt mix would do more than just decrease rutting. According to Wang, it would also lower pavement costs, decrease the amount of energy used in the pavement production process and decrease environmental pollution.
“This is a very important field for some time. The federal government has a goal I think by 2050 we have to reduce plastic pollution to a very low percent. Right now we have 91% of plastic in landfill or down in rivers, lakes, and beaches. So this research is very important.”
Preliminary results of the N-C Department of Transportation appear positive so far with the sample asphalt mix exhibiting “excellent to very good resistance to permanent deformation” according to an ECU News Release.
The state allows a maximum rut depth of 11.5 millimeters for local roads and 4.5 millimeters for interstate highways. Testing of various mixtures with the recycled masks show a rut depth range of .9 to 3.2 millimeters. The addition of the polymer fibers from the recycled masks, allows the mix to be used as a “higher grade road pavement.”
Wang says if commercialized this asphalt mix could revolutionize the future of asphalt paving.
“Normally every 15 to 20 years, you have to spend money in the government budget to repair roads because of distress or cracks or rotting. So if the design life is prolonged to 25 or 30 years, the construction costs on the federal state government budget can be saved to do other things. We’re always short of budget for infrastructure construction.”
A technical paper outlining this research is currently under review. Wang’s next step is to prepare a proposal for the Department of Energy.