PPE waste can make for stronger concrete

One of the most obvious material impacts of the COVID-19 pandemic has been the waste it produces: personal protective equipment (PPE) such as single-use masks are used and sent to the incinerator or landfill — or worse, make their way onto footpaths, roads and waterways.

Now researchers from RMIT University have developed a solution that can use disposable healthcare materials like masks, gloves and isolation gowns as a strengthening ingredient for concrete. The studies found shredded PPE could increase the strength of concrete by up to 22% and improve resistance to cracking.

Medical waste is a natural side effect of sanitary healthcare environments but COVID has been a major source of it since the pandemic began. About 54,000 tonnes of such waste is now being generated each day in the form of protective gear.

Three papers have been published by the RMIT scientists across three journals (Case Studies in Construction Materials, Science of the Total Environment and the Journal of Cleaner Production) looking at how to deal with this waste.

The three studies looked respectively at disposable plastic isolation gowns, nitrile gloves and surgical masks that had been shredded and added to concrete at various volumes between 0.1 and 0.25%.

The findings report various physical attributes of concrete could be improved: rubber gloves boosted compressive strength by up to 22%; isolation gowns increase resistance to bending stress by up to 21%, compressive strength by 15% and elasticity by 12%; and face masks improved compressive strength by 17%.

Of course, for sanitary reasons the waste equipment is quarantined and washed prior to being used.

The RMIT team’s industry partner, Casafico, which concentrates on recycling waste into construction material, is now planning on using the findings of these studies for a field project.

“We urgently need smart solutions for the ever-growing pile of COVID-19 generated waste — this challenge will remain even after the pandemic is over,” said first author, PhD researcher Shannon Kilmartin-Lynch.

“Our research found that incorporating the right amount of shredded PPE could improve the strength and durability of concrete.”

Joint lead author Dr Rajeev Roychand said construction industries would be able to both play a part in reducing waste while also benefiting from its strengthening properties.

“While our research is in the early stages, these promising initial findings are an important step towards the development of effective recycling systems to keep disposable PPE waste out of landfill,” Roychand said.

Corresponding author and research team leader Professor Jie Li said PPE waste, both from health care and the general public, represents a substantial problem for the environment and a challenge to be surmounted.

“We have all seen disposable masks littering our streets, but even when this waste is disposed of properly it all ends up in landfill,” Li said.

“With a circular economy approach, we could keep that waste out of landfill while squeezing the full value out of these materials to create better products — it’s a win on all fronts.”

The team will next be looking into combining the different sorts of healthcare waste to see how different ratios of the material can benefit the concrete, with field trials on the horizon.

The researchers are hoping to collaborate with businesses and organisations in the healthcare and construction industries to further develop the research.

Image credit: RMIT University