## 5 Conclusions and Prospect  
This study extended the MICP technique to the field of high-temperature concrete damage repair, and filled the research gaps of the influences of calcium source types and calcium source addition methods on mineralization products in MICP. In this work, the influences of calcium source types and calcium source addition methods on the mineralization products were studied, and the regulatory mechanism of calcium source types and calcium source addition methods on the mineralization products was revealed. The appropriate calcium source and calcium source addition method were determined, and the repair effect of MICP on high-temperature concrete damage was verified. Based on the results achieved during this study, the following conclusions are drawn:  
1. The mineralized products of _Sporosarcina pasteurii_ were white suspended pastes in solution and white powders after drying. Our analysis showed that the products were  
Figure 14: Process of water absorption test. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Damage Temperature/\({}^{\circ}\)C** & **Undamaged/\%** & **Damaged/\%** & **Repaired/\%** \\ \hline
300 & 3.81 & 4.87 & 3.77 \\
400 & 3.81 & 5.09 & 3.87 \\
500 & 3.81 & 5.6 & 3.98 \\
600 & 3.81 & 6.44 & 4.23 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Water absorption of concrete specimens under different conditions. CaCO\({}_{3}\), containing mixed crystals of vaterite and calcite, most of which were spheres and some of which were irregular shapes. 2. With all kinds of Ca\({}^{2+}\) sources and all addition methods, the mineralized products were CaCO\({}_{3}\). The mineralized products of the Ca(NO\({}_{3}\))\({}_{2}\) and CaCl\({}_{2}\) groups were more inclined to form calcite, while the mineralized products of the Ca(CH\({}_{3}\)COO)\({}_{2}\) group were unstable. This also depended on the method used to add the Ca\({}^{2+}\) source. The mineralized products of the post-calcium-source group were calcite, while those of the pre-calcium-source group were more inclined to form vaterite. The calcite morphologies were different, while the vaterite crystals were mostly spherical aggregates. Overall, Ca(CH\({}_{3}\)COO)\({}_{2}\) was the most suitable Ca\({}^{2+}\) source, while the pre-calcium-source addition method provided the most optimal results. 3. At each damage temperature, the compressive strength showed a certain degree of recovery, while the water absorption exhibited a certain degree of reduction, indicating that MICP resulted in an improvement in the mechanical properties and durability of the damaged concrete. The higher the damage temperature, the more obvious the repair effect. This study has guiding significance for the application of MICP in repairing high-temperature concrete damage. However, the actual application effect requires further examination. Firstly, mineralization conditions. Except for the types of calcium source and the calcium source addition methods, temperature, pH value, bacterial solution concentration, and repair fluid concentration also affect the mineralization process; however, the influences of mineralization conditions on mineralization products have not been studied in this work. Secondly, the repair method. The immersion repair method in this study can be used in the laboratory, but it is difficult to apply in practical engineering. For concrete structural components in practical engineering, our idea is to fix molds outside the components, and fill the gaps between the molds and the components with repair fluid, the repair fluid was pressed into the concrete cracks as much as possible by air pressure externally, or using an external vacuum pump to vacuum the gaps between the molds and the components before the repair fluid was inhaled. However, these are only possible ideas at present, the repair effect of these methods needs to be examined in further studies in practical engineering. Thirdly, rehydration of water.