Professor Jie Li from RMIT University speaks to AZoCleantech about his latest research into how disposable face masks can be used to enhance civil construction materials.
What do you know of the extent of face mask waste since the pandemic began?
The COVID-19 pandemic has created a global health and financial crisis and has had an unprecedented impact on the environment. We estimated that approximately 6.8 billion disposable face masks are being used across the globe each day. We also estimated that around 104 and 160 tons of used face masks were generated each day during the first and second waves of the coronavirus pandemic in Victoria, Australia, respectively.
What happens to disposable face masks when they are discarded? Do they have a lasting impact on our environment?
Face masks are ultimately sent to landfills or incinerated depending on the policy of countries. In Australia, they are mainly sent to landfills. But too many masks are finding their way out of bins and being blown into gutters and washing down the drain, impacting our waterways and wildlife. The most severe effect is that many masks find their way into rivers and oceans, threatening marine life and, consequently, human life. It has been reported that if the current trend of face mask generation continues, the number of masks in oceans could be higher than the number of fish.
Since disposable face masks are mainly made of non-biodegradable plastics, these single-use masks will take as long as 450 years to break down in the environment."
Professor Jie Li, RMIT University
Was disposable face mask waste an issue before the pandemic?
The generation of vast amounts of waste plastics, including PPE plastic-based waste, has always been an environmental issue. However, since the beginning of the pandemic, the amount of PPE plastic-based waste being used every day, including disposable face masks, has worsened the situation.
How did you begin your groundbreaking research into recycling face masks? What drove your team to investigate using them as a component in road-making materials?
The team was inspired to look at the feasibility of blending face masks into construction materials after seeing so many discarded masks littering their local streets.
Since disposable face masks are mainly made of non-biodegradable plastics, these single-use masks will take as long as 450 years to break down in the environment. Therefore, urgent action at every possible level is needed to reduce pandemic-generated waste.
How could using face masks in such applications help reduce pandemic-generated waste?
Adopting face masks in typically large-scale civil engineering applications will significantly reduce the amount of pandemic-generated waste going to landfill. For example, we found that to make 1 km of a two-lane road, around 3 million masks could be used in the road-making material we have developed.
It is estimated that around 6.8 billion disposable face masks are being used worldwide each day, with many of them polluting waterways and harming wildlife. Image Credit: REC Stock Footage/Shutterstock.com
How is it possible to use face masks for building roads? What purpose do they have?
First, the face masks need to be collected and extracted from other waste streams. As a suggestion, face masks can be extracted from the rest of the waste stream using blasts of air generated through air classifiers or air knives. Then, the face masks are disinfected and shredded into fibers/strips. They are then ready to be blended with processed building rubble or recycled concrete aggregate (RCA) for road-making materials.
Your research team is the first to investigate potentially using disposable face masks in civil construction applications. What are the engineering benefits involved with using face masks?
Shredded face masks play a reinforcing role in binding the rubble particles together. The introduction of randomly distributed shredded face masks enhanced the stretching resistance between aggregates. Consequently, the ductility, flexibility and strength of the rubble mixed with the mask fibers increased.
Is it possible that other types of personal protective equipment could be recycled in similar ways?
Given that most personal protective equipment (PPE) is mainly made of plastics, including polypropylene, polyvinyl chloride, and nitrile butadiene rubber, the proposed methodology can be applied to different PPE. A feasibility study, similar to our research, needs to be conducted to investigate other waste PPE's potential use with the rubble particles as pavement base/subbase materials.
What other methods could be used to disinfect and sterilize used masks to decrease the amount going to landfill?
Our study's main aim is to evaluate the effects of the shredded face mask on the stiffness and strength of the blends of face masks and rubble particles as road pavement material. We would like to collaborate with other researchers and industries to work on that specific area to disinfect the masks. We know that other researchers have looked at ways to sterilize the masks, and there are several methods available, including the “thermal method” and the “microwave method” that can kill 99.9% of viruses.
What are the next steps for your research?
Our team is now looking to partner with local governments or industry interested in collecting masks and building a road prototype.
Where can readers find more information?
Research paper: https://doi.org/10.1016/j.scitotenv.2021.145527
About Professor Jie Li
Professor Jie Li is the Discipline Leader (Civil Structures & Materials) at RMIT University with more than 25 years of professional experience as a consulting engineer, laboratory manager, researcher, and academic. He has acquired a national and international reputation in the broader field of civil/geotechnical engineering through his long history of applied research. He has outstanding knowledge and experience in civil engineering, geotechnics, pavement geotechnics, materials and aggregates, waste management, recycled materials in civil engineering, in-situ testing, and field instrumentation.
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