Mechanical and deformation behavior of clay reinforced by discarded mask fibers

Abstract

The outbreak and spread of the new coronavirus epidemic has caused a large number of using masks, which leads to a huge amount of discarded masks that may have serious effects on the ecological environment. To further verify the feasibility of the discarded masks for soil reinforcement and quantify its reinforcing effects, the tensile property tests of masks, the triaxial tests of mask fiber reinforced soil and the scanning electron microscope tests were carried out. The test results showed that the tensile strength of the discarded mask was about 15% lower than that of the new mask. Mask fiber reinforcement could improve the shear strength of clay and effectively restrain the bulging deformation of the soil specimen. At the optimum fiber content of 0.1%, the peak deviatoric stress was increased by around 20%. The reinforcing effect of discarded mask fibers for the same type of soil reached approximately 85% of that reinforced by polypropylene fibers. At a certain fiber content, the shear strength of the soil specimen was relatively high when the water content was low. The soil specimen showed a characteristic of brittle failure. With increasing water content, the shear strength of the soil specimen decreased and the plasticity gradually increased. It could be seen from the SEM images that the bonding and friction between the fibers and soil particles as well as the constraint behavior caused by the fiber webs were the main reasons for the strength improvement of the soil specimens. However, the reinforcing effect of polypropylene fiber was better because of its uniform distribution in the soil. The investigation results of this study can provide guidance for the application of discarded masks in geotechnical engineering.