PPE could be recycled to make stronger concrete

The team of engineers, from RMIT’s School of Engineering, is investigating the feasibility of recycling three key types of PPE – isolation gowns, face masks and rubber gloves – into concrete.

Published in the journals ‘Case Studies in Construction Materials’, ‘Science of the Total Environment’ and ‘Journal of Cleaner Production’, the three studies demonstrate the potential for PPE to be used as reinforcement materials in structural concrete.

The studies found shredded PPE could increase the strength of concrete by up to 22 per cent and improve resistance to cracking. Industry partner Casafico Pty Ltd is now planning to use the research findings in a field project.

Since the start of the Covid-19 pandemic, an estimated 54,000 tonnes of PPE waste has been produced on average globally each day. About 129 billion disposable face masks are used and discarded around the world every month.

Shannon Kilmartin-Lynch, first author and PhD researcher, said the research brought a circular economy approach to the challenge of dealing with healthcare waste: “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.

“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 there was real potential for construction industries around the world to play a significant role in transforming this waste into a valuable resource.

“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,” he said.

In three separate feasibility studies, disposable face masks, rubber gloves and isolation gowns were first shredded then incorporated into concrete at various volumes, ranging between 0.1 per cent and 0.25 per cent.

The research found that rubber gloves increased compressive strength by up to 22 per cent, while isolation gowns increased resistance to bending stress by up to 21 per cent, compressive strength by 15 per cent and elasticity by 12 per cent. Face masks were observed to increase compressive strength by up to 17 per cent.

Corresponding author and research team leader Professor Jie Li said that PPE waste – both from health care and the general public – was having a significant impact on the environment.

“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 next step for the research is to evaluate the potential for mixing the PPE streams, develop practical implementation strategies and work towards field trials.

The cement and concrete industry is facing increasing scrutiny for the significant role it has to play in helping governments worldwide achieve net-zero targets. It has been widely acknowledged that concrete accounts for at least 7 per cent of total global CO2 emissions – a figure that has to come down.

Global policymakers, including the United Nations, the US Department of Energy, global economists and built environment leaders, met cement and concrete industry CEOs in June this year to discuss how to build a sustainable future built environment.

Research into concrete additives or alternatives actively continues. In June, a team of Spanish scientists published their findings on the efficacy of using volcanic ash from the Cumbre Vieja volcano, on the island of La Palma, to manufacture cement and concrete.

Meanwhile, a University of Colorado Boulder-led research team has suggested that cities of the future could be built with algae-grown limestone using a method that could potentially make cement production carbon neutral.

The mountain of PPE waste produced around the world, exponentially increased by the Covid-19 pandemic, has resulted in various approaches towards tackling the problem.

Earlier this year, for example, one UK-based PPE manufacturer announced that it had developed a new process to turn its used PPE product into an oil that can then be repurposed to make new products or fuel.

Meanwhile, in June, the UK government announced its plan to burn £4bn of unusable PPE panic-purchased at the start of the pandemic, including the infamous 50 million face masks that were quickly deemed not fit for purpose for use by the NHS. The plan to burn this PPE wholesale inevitably raised serious environmental concerns from MPs.