Abstract: To explore the effect of fiber on the self-healing effect of microbial concrete cracks, polyacrylonitrile fiber is selected and incorporated into microbial concrete; an experiment is conducted to test the mechanical properties of microbial concrete blended with fiber, its crack permeability, and the residual crack width during its self-healing cure. The results show the concrete specimen with a fiber content of 1.5 kg/m3 has a splitting tensile strength that recovers to 95.1% of that of the specimen without microbial carrier. After 28 days, the permeability coefficient of the specimen with an average crack width of 0.43 mm is lowered from 3.35×10-5 m/s to 3.40×10-6 m/s, or a relative decrease of 89.9%. The maximum width of cracks that can self heal is 0.82 mm. The incorporation of fiber into microbial self-healing concrete effectively improves its crack resistance and enhances the self-healing effect of cracks.

Key words: hydraulic concrete, mineralized microorganisms, MICP, fiber, mechanical properties, crack self-healing