Face masks to bring the roads back to life

Australian researchers say they have shown that single-use disposable face masks can be used successfully in recycled concrete aggregate for paving roads.

The new road building material is a mix of shredded used face masks and processed construction rubble developed at RMIT University. The mixture meets civil engineering safety standards, according to a press release from the institute. RMIT University, formerly the Royal Melbourne Institute of Technology and Melbourne Technical College, is a public research university in Melbourne, Australia. It has been ranked as the best art and design university in Australia.

Analysis shows that face masks help add stiffness and strength to the end product that is designed for use in the base layers of roads and pavements.

The researchers’ study will appear in the weekly Total environmental science, published by Elsevier. According to the publication’s website, “Total environmental science is an international multidisciplinary journal for the publication of innovative research, based on hypotheses and with a strong impact on the total environment, which connects the atmosphere, the lithosphere, the hydrosphere, the biosphere and the anthroposphere ”.

“This initial study examined the feasibility of recycling single-use masks in roads and we were delighted to see that it not only works, but also offers real technical benefits,” said Mohammad Saberian, lead author of a study report. “We hope this opens the door to further research, to find ways to manage health and safety risks on a large scale and to determine if other types of PPE [personal protective equipment] would also be suitable for recycling.

In Australia alone, around 3.15 million tonnes of recycled concrete aggregate (RCA) is added to inventory each year rather than being reused. The experimental study was conducted with a small amount of unused surgical masks. He identified an optimal blend – 1% shredded masks for 99% RCA – that provides strength while maintaining good cohesion between the two materials.

The blend performs well when tested for stress, acid and water resistance, as well as strength, deformation and dynamic properties, meeting all relevant civil engineering specifications, the release noted. Press.

According to the study summary, “for the first time” a series of experiments, including tests of modified compaction, unconfined compressive strength and modulus of resilience, were carried out on the mixtures of different percentages. of the shredded face mask (SFM) added to the RCA. for basic road and subbase applications. Experimental results show that RCA mixed with three different percentages – 1%, 2% and 3% – of SFM satisfied the stiffness and strength requirements for the pavement base / subbase.

The introduction of the shredded face mask not only increased strength and stiffness, but improved the ductility and flexibility of RCA / SFM blends. The inclusion of 1% SFM in RCA gave the highest values ​​of unconfined compressive strength (216 kPa) and highest modulus of elasticity (314.35 MP).

However, above 2%, increasing the amount of SFM led to a decrease in strength and stiffness.

A free downloadable pdf is available now prior to official release later this year and some changes may be made prior to that date.

M. Saberian, J. Li, S. Kilmartin-Lynch, et al., Reuse of COVID-19 single-use face masks for the base / sub-base of sidewalks, with co-authors Shannon Kilmartin-Lynch, Indigenous undergraduate RMIT researcher and Mahdi Boroujeni, research assistant, is published in Science of the Total Environment (DOI: 10.1016 / j.scitotenv.2021.145527).

In related work, researchers at RMIT said they had also investigated the use of shredded disposable face masks as aggregate material for making concrete, with promising preliminary results.

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