Self-healing mechanism and crack-filling performance of multifunctional bacteria-laden fiber (bioFiber) in cementitious matrix

Abstract This study investigates the self-healing mechanism and crack-mitigation behavior of multifunctional bacteria-laden fibers (bioFibers) embedded in a cementitious matrix. Each bioFiber comprises a polymeric core, an endospore-laden alginate hydrogel sheath, and an outer protective shell, enabling localized microbial-induced calcium carbonate precipitation (MICCP) under wet/dry cycles. Quantitative and microstructural analyses (optical imaging, TGA, SEM, XRD) demonstrate that bioFibers achieve up to 99 ± 4% crack filling for 120–150 μm cracks and sustain measurable healing of 31 ± 7% even beyond 300 μm. Crystal phase evolution indicates a transformation from vaterite to calcite between 7 and 21 days, while TGA confirms progressive calcium carbonate formation from 15 ± 1% to 55 ± 3% over 28 days. These findings highlight bioFiber’s effective crack-filling capability, healing potential, and adequate fiber–matrix bridging effect, demonstrating its promise for robust self-healing cementitious composites.