Repair of Flexurally Cracked Concrete Beams under Sustained Loading via a MICP Diffusion Method

Most studies on microbially induced calcium carbonate precipitation (MICP) for concrete crack repair focus on unloaded members, while cracks in service are commonly subjected to sustained loading. This study proposes a diffusion-based MICP method for flexurally cracked concrete beams under sustained loading and compares it with a conventional injection method used for unloaded specimens. Five reinforced concrete beams were prepared and evaluated through chloride resistance tests and microstructural analysis. The results show that the diffusion method can effectively seal working cracks and reduce the apparent chloride diffusion coefficient by 54.75% compared with unrepaired specimens. Its durability improvement is comparable to that of the injection method, indicating good potential for engineering applications.