Scientists Recycle Face Masks Into Roads to Fight COVID Waste

Researchers at RMIT University in Australia have discovered that disposable face masks can be recycled to build paved highways. A study published in the journal "Science of the Total Environment" found that just one kilometer (0.62 miles) of a two-lane road could use around 3 million face masks, diverting 98 tonnes of waste from landfill.

The study was inspired by researchers seeing significant numbers of single-use masks discarded in their city streets. The scale of this plastic pollution is enormous, with an estimated 6.88 billion face masks being used every day around the world. These are sent to landfill or incinerated because they have no other purpose at this point. Both disposal methods are far from ideal, causing environmental and health problems, but landfill in particular allows the lightweight masks to blow away and contaminate rivers, oceans, and other waterways.

The researchers wondered if there was some way in which these masks could be repurposed, so they began experimenting with mixing shredded face masks with recycled concrete aggregate (RCA), also known as processed building rubble, for use as a road-building material. A press release from RMIT University explains that "construction, renovation and demolition account for about half the waste produced annually worldwide, and in Australia, about 3.15 million tons of RCA is added to stockpiles each year rather than being reused." 

A ratio of 1% shredded face masks and 99% RCA was found to be the ideal mix, delivering strength while maintaining cohesion between the two materials. (Anything beyond 2% of shredded face masks was found to decrease strength and stiffness.) The new material passed tests for "stress, acid and water resistance, as well as strength, deformation and dynamic properties, meeting all the relevant civil engineering specifications."

Roads typically require four layers to be built – sub grade, base, sub-base, and asphalt. RCA, however, can potentially be used on its own for the bottom three layers, and when combined with shredded face masks, offers a comprehensive solution to two separate waste problems that results in a 100% recycled product. 

So far the research has only used new face masks, but the goal is to find a good sterilization technique that will allow for used masks. Dr. Mohamad Saberian, lead study author, told Treehugger that he hopes to collaborate with other researchers and industries in that specific area of disinfecting masks so they can be used in a broad range of engineering applications. 

"We know that other researchers have looked at sterilization and there are several methods available for disinfecting face masks, including the 'thermal method' and the 'microwave method' that can kill 99.9% of viruses."

This road-building material would contribute to a circular economy, and Saberian said his team is eager to partner with local governments or industries that are interested in collecting masks and building a road prototype. So far the research has been restricted to a preliminary study, asking the specific question of whether face masks can be repurposed in this way, but hopefully it's just the beginning. "We are currently evaluating the effects of other polypropylene waste and PPE waste on the performance of roads," he said.

When asked what happens at the end of a road's average 20-year lifespan, Saberian told Treehugger that the layers can be excavated and the materials recycled and reused for the next road-building projects. 

Read the full study here.