• Disposable masks could be used to improv

    From ScienceDaily@1:317/3 to All on Wed Apr 27 22:30:50 2022
    Disposable masks could be used to improve concrete

    Date:
    April 27, 2022
    Source:
    Washington State University
    Summary:
    With the pervasive 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.



    FULL STORY ==========================================================================
    With the pervasive 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.


    ==========================================================================
    In a paper published in the journal, Materials Letters, a Washington State University research team showed that the mixture using mask materials
    was 47% stronger than commonly used cement after a month of curing.

    "These waste masks actually could be a valuable commodity if you process
    them properly," said Xianming Shi, professor and interim chair of the Department of Civil and Environmental Engineering and the corresponding
    author on the paper.

    "I'm always looking out for waste streams, and my first reaction is 'how
    do I turn that into something usable in concrete or asphalt?'" Production
    of cement is a carbon-intensive process, responsible for as much as 8%
    of carbon emissions worldwide. Microfibers are already sometimes added to cement concrete to strengthen it, but they're expensive. The microfiber- reinforced concrete can potentially reduce the amount of cement needed
    for a project or make the concrete last longer, saving carbon emissions
    as well as money for builders and owners.

    Made of a polypropylene or polyester fabric where it contacts the skin and
    an ultra-fine polypropylene fiber for the filtering layers, medical masks
    have fibers that can be useful for the concrete industry. If they are
    not reused, disposable masks can remain in the environment for decades
    and pose a risk for the ecosystem.

    "This work showcases one technology to divert the used masks from the
    waste stream to a high-value application," Shi said.

    In their proof-of-concept work, the researchers developed a process to fabricate tiny mask fibers, ranging from five to 30 millimeters in length,
    and then added them to cement concrete to strengthen it and to prevent
    its cracking. For their testing, they removed the metal and cotton loops
    from the masks, cut them up and incorporated them into ordinary Portland cement, the most common type of cement used around the world and the
    basic ingredient for concrete, mortar and grout.

    They mixed the mask microfibers into a solution of graphene oxide before
    adding the mixture to cement paste. The graphene oxide provides ultrathin layers that strongly adhere to the fiber surfaces. Such mask microfibers
    absorb or dissipate the fracture energy that would contribute to tiny
    cracks in the concrete. Without the fibers, these microscopic cracks
    would eventually lead to wider cracks and the material's failure.

    The researchers are conducting more studies to test their idea that the graphene oxide-treated microfibers 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 incentivize the collection of such waste.

    Zhipeng Li, a graduate student in WSU's Department of Civil and
    Environmental Engineering, led the work, which was funded through the
    U.S. Department of Transportation's National Center for Transportation Infrastructure Durability and Life Extension.


    ========================================================================== Story Source: Materials provided by Washington_State_University. Original written by Tina Hilding. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Zhipeng Li, Zhigang Zhang, Ming-en Fei, Xianming Shi. Upcycling
    waste
    mask PP microfibers in portland cement paste: Surface treatment by
    graphene oxide. Materials Letters, 2022; 318: 132238 DOI: 10.1016/
    j.matlet.2022.132238 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220427100444.htm

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