Influence of Repairing Technical Parameters on the Healing Efficiency of Biological Calcium Carbonate–Based Mortar Crack Healing Efficiency

The recently emerged microbial induced calcium carbonate precipitation (MICP) offers several advantages, including high fluidity and low viscosity. The product CaCO3 exhibits excellent compatibility with the concrete matrix, making it ideal for repairing microcracks. Most of the current research focuses on the optimization of the components of repair agents. However, repair process parameters directly affect the deposition process in cracks. To clarify the repair process parameters during crack repair, we investigated the influence of three key repairing parameters, grouting rate, presealing length, and grouting location, on crack repair efficiency. The results show that the most effective MICP repair parameters for mortar samples involved injecting the repair solution at a grouting rate of 7.96 μL/min, with full crack sealing and the grouting location at the bottom. Under these conditions, the surface repair rate of the mortar post-MICP treatment achieved 88.22%, and the compressive strength recovery rate reached 83.9%. The primary reasons for the low crack surface repair rate and low compressive strength recovery rate of mortar specimens under the nonoptimal process outlined in this article are limited calcium carbonate production or disrupted further hydration of the mortar matrix.