Durable and Impermeable Cement-Based Material Crack Repair via MICP: Synergistic Effects of Biopolymeric Additives and Repeated Repairs

Abstract

Microbial-induced calcium carbonate precipitation (MICP) represents an innovative approach for the remediation of cement-based material cracks, addressing the limitations of conventional repair methods, such as high cost, low efficiency, and challenges in repairing fine cracks. In this study, we observed the growth of urease and determined optimal calcium sources for the mineralization process. It was found that the mineralization efficacy is positively correlated with the calcite content in the precipitated calcium carbonate. Furthermore, we systematically optimized key parameters of the mineralization reaction, including cementation solution concentration, pH, and temperature, to enhance the overall performance of the MICP process. To improve the mechanical strength of MICP-repaired mortar cracks, TC-EM300 interface emulsion was incorporated into the grouting solution, along with a biopolymeric additive for enhanced impermeability. The experimental findings suggest that high-molecular-weight dextran facilitates the formation of a polysaccharide–calcium carbonate biocomposite during calcite precipitation, thereby significantly enhancing impermeability. Furthermore, it mitigates grout leakage by increasing the viscosity of the solution. In addition, the feasibility of repeated MICP-based repairs was evaluated through tensile strength and water permeability tests. The findings indicated that repeated applications of MICP do not compromise the structural integrity of the mortar and may even enhance its impermeability.