Bridge crack self-repairing based on nanosilica-modified bacterial solution

To address the challenge of self-healing concrete cracks (CCs) in bridge structures, a nano-SiO₂-modified bacterial solution was developed and systematically evaluated for its effectiveness in enhancing crack healing performance. Calcium lactate, used as a calcium source, increased the surface roughness of calcium carbonate crystals, enhancing Ca²⁺ adsorption and achieving a mineralization efficiency (ME) of 2.18 mol/h at 36 h. The optimized application process—three treatments at 15-minute intervals—significantly reduced the concrete’s chloride migration coefficient (8.48 × 10-13 m2/s), electrical flux (327 C), and carbonation depth (2.8 mm after 13 days). After 28 days, the bacterial group repaired over 95% of both primary and secondary crack areas. These improvements are attributed to nano-SiO₂ providing a high specific surface area for microbial adhesion and promoting calcium carbonate precipitation, thus accelerating crack closure. The proposed nano-SiO₂-modified bacterial solution offers a sustainable and efficient approach to enhancing the durability and protective performance of concrete in bridge applications.