A Washington State University research team showed that the mixture using mask materials was 47 percent stronger than commonly used cement after a month of curing
Voiland College of Engineering and Architecture
Washington State University
PULLMAN, Wash. – With the pervasive single-use masks during the pandemic now presenting an environmental problem, researchers have demonstrated the idea of incorporating old masks into a cement mixture to create stronger, more durable concrete.
In a paper published in the journal, Materials Letters, a Washington State University research team showed that the mixture using mask materials was 47 percent stronger than commonly used cement after a month of curing.
“These waste masks actually could be a valuable commodity if you process them properly,” said Xianming Shi, professor and interim chair of the Department of Civil and Environmental Engineering and the corresponding author on the paper. “I’m always looking out for waste streams, and my first reaction is ‘how do I turn that into something usable in concrete or asphalt?’”
Production of cement is a carbon-intensive process, responsible for as much as 8% of carbon emissions worldwide. Microfibers are already sometimes added to cement concrete to strengthen it, but they’re expensive. The microfiber-reinforced concrete can potentially reduce the amount of cement needed for a project or make the concrete last longer, saving carbon emissions as well as money for builders and owners.
Made of a polypropylene or polyester fabric where it contacts the skin and an ultra-fine polypropylene fiber for the filtering layers, medical masks have fibers that can be useful for the concrete industry. If they are not reused, disposable masks can remain in the environment for decades and pose a risk for the ecosystem.
“This work showcases one technology to divert the used masks from the waste stream to a high-value application,” Shi said.
In their proof-of-concept work, the researchers developed a process to fabricate tiny mask fibers, ranging from five to 30 millimeters in length, and then added them to cement concrete to strengthen it and to prevent its cracking. For their testing, they removed the metal and cotton loops from the masks, cut them up and incorporated them into ordinary Portland c