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With single-use masks during the pandemic now presenting an environmental problem, researchers have demonstrated the idea of incorporating old masks into a cement mixture to create stronger, more durable concrete. If they are not reused, disposable masks can remain in the environment for decades and pose a risk for the ecosystem.
In a paper published in the journal Materials Letters, researchers showed that the mixture using mask materials was 47% stronger than commonly used cement after a month of curing, Washington State University said in a press release.
Production of cement is a carbon-intensive process, responsible for 8% of carbon emissions worldwide. If concrete is reinforced with microfibres, it can potentially reduce the amount of cement needed for a project, or make the concrete last longer, saving carbon emissions as well as money. Medical masks have fibres that can be useful for the concrete industry.
“These waste masks actually could be a valuable commodity if you process them properly… This work showcases one technology to divert the used masks from the waste stream to a high-value application,” the release quoted the paper’s corresponding author Xianming Shi, professor of civil and environmental engineering, as saying.
The researchers developed a process to fabricate tiny mask fibres, ranging from 5 mm to 30 mm in length, and then added them to cement concrete to strengthen it and to prevent its cracking. They removed the metal and cotton loops from the masks, cut them up and incorporated them into ordinary Portland cement. They mixed the mask microfibres into a solution of graphene oxide before adding the mixture to cement paste. Without the fibres, microscopic cracks in the concrete would eventually lead to wider cracks and the material’s failure, the release said.
The researchers are conducting more studies to test their idea that the graphene oxide-treated microfibres could also improve the durability of the concrete and protect it from frost damage and from deicing chemicals that are used on roadways. They also envision applying this technology to the recycling of other polymer materials, such as discarded clothing, to incentivise the collection of such waste.
The study was led by Zhipeng Li, a graduate student in WSU’s Department of Civil and Environmental Engineering. The study was funded through the US Department of Transportation’s National Center for Transportation Infrastructure Durability and Life Extension.
STUDY: ‘Upcycling waste mask PP microfibers in Portland cement paste: Surface treatment by graphene oxide’, Zhipeng Li et al, Materials Letters, 2022. doi.org/10.1016/j.matlet.2022.132238
Source: Washington State University
