Recycle of discarded masks in civil Engineering: Current status and future opportunities with silane coupling agent modified discarded masks

•Various disposal techniques for recycling discarded masks were summarized.•Current status of recycle of discarded masks in civil engineering were studied.•Mechanical properties of slurry with silane coupling agent modified discarded masks. In recent years, with the heightened of public health protection awareness, masks have become an important protective equipment. The accumulation of discarded masks (DM) poses an impact to environment and resource. Recycling DM has become a prime focus of sustainable development research. This investigation introduces a review of the recycling of DM in civil engineering and presents a novel modification of discarded mask fibers (DMF) to enhance the mechanical property of cement paste. In the review section: (1) The masks are divided into three classes by integrating relevant standards and considering mask protective characteristics; (2) Various disposal techniques for recycling DM are categorized in shredding, hot processing, paper shredding, and crushing; (3) The impact of incorporating DMF in concrete, mortar, asphalt, road subbases and base courses are discussed. The enhancement of applying DMF into composite materials varies depending on the specific application. In the experimental research section, the silane coupling agent (SCA) is introduced as a modification to improve the weak bonding between DMF and composite materials. The SCA-modified polypropylene (PP) fibers were conducted as a control group. The results indicate that the compressive strength of cement paste with both SCA-modified DMF and PP fibers increased by 12.29 % and 26.10 %, respectively. Finally, several future opportunities in recycling of DM in Civil Engineering were drawn.