Regulation of Calcium Source and Addition Method for MICP in Repairing High-Temperature Concrete Damage

Abstract

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.

Culture optimization and regulation mechanism of sporosarcina pasteurii for restoring root splitting fissures in Jinyang ancient city

“…It can be concluded that due to the high temperature at 37 ℃, inhibiting the growth, reproduction, and metabolism of Pasteurii by affecting enzyme activity, cell membrane fluidity, and substance solubility could lead to premature entry into its stable and declining growth period. In summary, the bacteria concentration and urease activity were relatively good at 30 ℃, which was consistent with the thesis conclusion of Dr. Wei [11]. It is recommended to set the culture temperature to 30 ℃.…”

“…However, its quantitative indicators could not be directly obtained. Research has shown that the amount of Pasteurii urease increased the ion concentration in the bacteria solution when decomposing urea, leading to an increase in the conductivity of the bacteria solution [11]. Urease activity could be characterized by measuring the growth rate of conductivity in bacteria solution.…”

“…At this stage, the cementing performance [6][7][8][9] is widely studied and applied for patents [10]. Research has confirmed that Pasteurii [11] had a diameter of 0.5μm and a length of 2μm, meeting the standard of micron restoration for root splitting fissures. Pasteurii was an aerobic strain that prioritized sealing surface fissures.…”