Used face masks could find new life in stronger concrete
Over the past couple of years, disposable face masks have become a very plentiful form of garbage. There may actually be a use for them, however, as recent research shows that they could strengthen concrete when added to it.
Previous studies have indicated that concrete is less prone to crack when tiny reinforcing fibers are mixed into it before it's poured. With that fact in mind, scientists at Washington State University wondered if the polypropylene or polyester fabric in discarded face masks could be a source of those fibers.
In order to find out, the researchers started by removing the metal nose-bridges and cotton ear loops from disposable surgical masks, then shredding the remaining fabric into fibers ranging from 5 to 30 mm in length.
Next, the fibers were treated with a graphene oxide solution. It formed a coating on them, adding extra surface area which helped them bond with commonly used Portland cement paste. They were added to that cement – which is the binding ingredient in concrete – at a volume of 0.1 percent.
When the fiber-reinforced cement was tested a month after curing, it was found to exhibit 47 percent more splitting tensile strength than untreated Portland cement. It should be noted that the addition of the fibers did produce a slight decrease in compressive strength, although it was only 3 percent.
"This work showcases one technology to divert the used masks from the waste stream to a high-value application," said the lead scientist, Prof. Xianming Shi.
A paper on the research was recently published in the journal Materials Letters.
Last year, a study conducted at Australia’s RMIT University likewise showed that face mask fibers helped strengthen asphalt and underlying road materials.
Source: Washington State University