In 2021, RMIT tested shredded face masks with recycled concrete for road bases; 1 kilometer could use 3 million masks and divert 93 tonnes from landfill

An Australian university has found a way to turn waste into pavement, and the approach could help US road builders address a difficult disposal problem. In 2021, engineers at RMIT University in Melbourne mixed shredded single-use face masks with crushed concrete to build the base layers of a road. According to RMIT University's study, "Repurposing of COVID-19 single-use face masks for pavements base/subbase," published in Science of the Total Environment, one kilometer of a two-lane road built with this material could use about 3 million masks while keeping 93 tonnes of waste out of landfill. That finding matters because disposable masks piled up worldwide during the pandemic, with few clear disposal paths. I think this could help road builders and reduce waste.

Why millions of masks needed somewhere to go

For years, people threw away masks every day. According to a study from RMIT, the number of masks used worldwide each day reached about 6.8 billion at the peak of the pandemic. That is a lot of masks, and most of the places where people live were not ready to deal with that kind of waste. The team from RMIT worked on this problem. They looked at the fact that masks are made of layers of fibers that do not break down quickly, and few cities had a way to recycle them properly. Instead of trying to change how people act, the RMIT team asked an important engineering question: could a mask be used to help make something instead of ending up in a landfill? The answer was yes, with a big condition: the tests used new, unused masks rather than ones collected from public places, since used masks would need to be cleaned before they could be reused safely.

How shredded masks end up in a road

Roads are much more than a flat layer of black asphalt. Underneath the surface are the base and sub-base layers, usually made from crushed rock or recycled concrete. These layers carry the load of traffic without cracking under repeated stress. The engineers at RMIT replaced about 1 percent of that base material with shredded masks mixed into recycled concrete aggregate, or crushed demolition rubble.

That tiny change actually made a difference. The RMIT research team said that the shredded fibers helped hold the mixture and added some flexibility. The final blend met the study's tests for strength, water resistance and durability. Professor Jie Li, who led the RMIT engineering team, said the idea for the project came from seeing discarded masks littering local streets, though for safety reasons, the actual lab tests were run on new, unused masks rather than ones collected from the litter that inspired the project.

Why this matters for US roads too

The findings may also be relevant to the United States. The United States already relies heavily on recycled materials in highway construction. According to the Federal Highway Administration, state transportation agencies should consider recycled materials first when planning projects. Recycled asphalt pavement is one of the most widely used construction materials in the country. Adding a pandemic-era waste stream to that system would likely not require a major change in current practice, though no agency has evaluated this specific application. Separately, the U.S. Environmental Protection Agency urged Americans in 2020 to recycle materials and dispose of personal protective equipment properly, as the pandemic had strained supply chains for recyclable materials generally, a broader waste-management concern rather than one specific to road construction.

What still needs to happen before this scales up

This is not a product ready for widespread use. The RMIT study was a small lab experiment using new masks, and the scientists said more research is needed to learn how to collect and clean used masks safely at scale before this idea can be used in real life. Safety rules for handling protective equipment remain a major hurdle, and building a system to collect and sort millions of masks is also difficult.

Still, the core idea is promising. It shows that a type of waste that no one wanted, which seemed like a lot during the worst of the pandemic, could help build the roads and structures that people use every day. For readers who have heard a lot about recycling but rarely seen it work at scale, this is a concrete example with plausible numbers. A road that looks normal from the surface might contain material made from single-use masks.