A Review of Urease-Based Biomineralization: MICP and EICP

Microbial-induced calcite precipitation (MICP) and enzyme-induced calcite precipitation (EICP) have emerged as research hotspots in recent years at the intersection of geotechnical engineering, environmental engineering, and materials engineering. Compared with traditional grouting reinforcement and repair methods, these methods exhibit greater environmental benignity, higher calcium carbonate precipitation yield, and more significant improvement in mechanical properties of repaired materials. The urease activity in the urease-based MICP and EICP techniques lies at the core of rock fracture repair, soil reinforcement, and concrete crack remediation. This paper presents a systematic review of urease-based MICP and EICP repair technologies, focusing on repair principles, environmental influencing factors, research methods, and application approaches, including microbial cultivation, enzyme activity determination, preparation of cementing solutions, selection of carriers, injection methods, and repair cycles. It also compares the advantages and disadvantages of MICP and EICP. This review clarifies the intrinsic similarities and differences between the two technologies in mineralization mechanism, crystal characteristics and engineering applicability, and constructs a complete technical system of urease-based biomineralization. Additionally, this paper discusses current macroscopic and microscopic evaluation methods for biomineralization repair effects, synthesizes existing mineralization repair systems, and assesses the challenges of self-healing biomaterials, including long-term microbial durability, repair strength stability, and the overall cost of widespread application. It includes long-term microbial durability, repair strength stability, enzyme activity retention, and the overall cost of widespread application, which are key issues to be solved for engineering implementation. The aim of this study is to provide a theoretical and practical reference for the theoretical improvement and engineering application of EICP and MICP technologies.