Reusable masks aren’t always an option. But there could be a happy ending for disposable masks.
A new Australian study suggests disposable face masks used to prevent the spread of Covid-19 should be recycled to make roads. Engineers say their road-making material will tackle the waste generated from Covid protective equipment.
The research by the Royal Melbourne Institute of Technology (RMIT) has developed a construction product (RCA) from combining shredded single-use masks and building rubble. The study, published in the journal Science of the Total Environment, estimated that making 1 km of two-lane road would use 3 million masks and prevent 93 tonnes of waste going to landfill. Moreover, the recycled material would meet road safety standards and provide an eco-solution to the mounting Covid PPE problem.
The UN called the influx of single-use masks a “toxic problem”; we’re now using more than 6.8 billion of them a day globally. It estimates that 75% of used masks and other pandemic-related waste will end up in landfills or the ocean. The lead author of the study, Dr Mohammad Saberian cofirmed. “We saw the masks in parks and streets in every suburb,” he explains. “We were inspired by the idea to look at circular economy solutions and reduce the pandemic-generated waste.” As well as mitigating the environmental impact of discarded PPE, researchers found improvement in the road’s strength, ductility, and flexibility.
According to Jie Li, another RMIT professor, rubble mixed with face masks could be used for two of the four layers generally used to make roads. The plastic polypropylene in face masks doesn’t decompose. However, it can reinforce the binding between rubble particles and increase stretching making the road more resistant to wear than traditional asphalt. “We need to have flexible roads, otherwise the road structure wouldn’t be able to sustain the wheel loads. Masks or plastic can provide such a good flexibility property,” he said.
Road to Recovery
In terms of RCA production, the size of the discarded masks make them easier to handle and process than most waste. The plastic is extracted using blasts of air from either an air classifier, (a chimney that sucks air out) or air knives (a curtain of compressed air).
Initial cost analysis suggests a ton of RCA costs $26 to produce compared to $50 per ton of mined quarry material. The mask collection, disinfection, and transportation costs would be balanced by the costs of disposing of them in a landfill. This runs at about $32 and $78 per ton in urban areas in Australia.
“Using face masks with recycled concrete aggregate as an alternative material would not only reduce pandemic-generated waste and the need for virgin materials but also reduce construction costs by about 30%,” Li estimates.
Next steps for the MIT team are to secure construction industry partnerships in order to build a prototype manufacturing unit.
The Australian team aren’t the only engineers repurposing plastic waste for road-making. India, Ghana and the Netherlands have all been experimenting with plastic-tar roads since the early 2000s.
A road linking New Delhi to Meerut was laid using a system developed by Rajagopalan Vasudevan, a professor of chemistry at the Thiagarajar College of Engineering in India.
Carrier bags, disposable cups, hard-to-recycle multi-layer films and polyethylene and polypropylene foams are reprocessed using simple technology. Plus, there is no need for sorting or cleaning. In 2015, it became mandatory for plastic waste to be used in constructing roads near cities of more than 500,000 people after Vasudevan gave his patent to the government for free.
Similarly, the UK government has committed £1.6m for research on plastic road materials to help fix and prevent potholes. In the Netherlands, PlasticRoad uses discarded festival mugs, cosmetics packaging, bottle caps, plastic straws, and no bitumen to produce recycled-plastic cycle paths.
According to the company website, “Each square metre of the plastic cycle path incorporates more than 25kg of recycled plastic waste, which cuts carbon emission by up to 52% compared to manufacturing a conventional tile-paved bike path.”
See how plastic waste is being upcycled into construction bricks here.