Sustainable Use of COVID-19 Face Masks in Asphalt Binder and Asphalt Mixture.

The disposal of waste face masks (FM) caused by COVID-19 has become an increasingly severe problem. In order to alleviate this issue, this paper proposes an approach of adding face mask waste as modifiers to asphalt. Extensive performance tests evaluated the feasibility of FM in asphalt binders, including rotational viscosity and rheological behaviors at different temperatures, aging performance, separation tendency, and modification mechanism. Based on this, the road performance of FM-modified asphalt mixtures were also investigated. The results showed that FM increased the rotational viscosity, high-temperature performance, and anticreep performance, whereas it had a negative effect on the stress change sensitivity, low-temperature performance, aging performance, and storage stability of asphalt binder. Based on the linear amplitude sweep test results, the incorporation of FM contributed to the material integrity and load resistance capacity of asphalt binder, whereas it was not conducive to its antideformation performance. According to Fourier transform infrared spectroscopy and fluorescence images, the modification process of FM with a chemical composition of polypropylene was mainly a physical blend, and 5% FM had the best compatibility with asphalt. The addition of FM could improve Marshall stability, rutting resistance, low-temperature cracking resistance, and moisture susceptibility of an AC-13 mixture. The 5% FM-modified asphalt and asphalt mixture met the specific road requirements. The experiment results could provide a new way to deal with waste FM by recycling. [ABSTRACT FROM AUTHOR]