LAUSR

After exposure to high temperatures, the mechanical properties and durability of concrete structures are significantly reduced, and effective measures must be taken for reinforcement and repair. High-temperature concrete damage manifests as looseness, spalling, and cracks, which are suitable for microbial-induced carbonate precipitation. When repairing high-temperature concrete damage with microbial-induced carbonate precipitation (MICP), the calcium source is an important influencing factor. The type of calcium source and the method used to add calcium source will directly affect the mineralized products, which in turn affect the quality of the repair. In this study, the mineralized products of Sporosarcina pasteurii were qualitatively analyzed and the appropriate type of calcium source and addition method were determined. The repair effect on high-temperature concrete damage was also verified. The results showed that the mineralized products of Sporosarcina pasteurii were calcium carbonate, with mixed vaterite and calcite crystals. Calcium acetate was found to be the most appropriate calcium source, while the pre-calcium-source addition method was shown to be optimal. At each damage temperature, the compressive strength showed a certain degree of recovery, and the water absorption exhibited a certain degree of reduction. At 600 °C, the compressive strength of the repaired specimens increased up to 202.68% compared with the damaged specimens and the water absorption of the repaired specimens was 34.32% lower than that of the damaged specimens. The higher the damage temperature, the more obvious the repair effect.