Progress in the application of MICP for reinforcement and restoration in soil and cement-based materials

Background Microbial-induced calcium carbonate precipitation (MICP), as an environmentally friendly and highly controllable biomineralization technology, is rapidly developing in soil reinforcement and cement-based material repair. It aligns well with the urgent demand for green, low-carbon technologies under China's national eco-civilization construction and "dual carbon" (carbon peak and carbon neutrality) strategy. However, existing research predominantly focuses on single media (soil or concrete), lacking a systematic cross-scale comparison and integrated analysis of MICP's mechanisms, performance evolution patterns, and application bottlenecks within these two critical engineering media. This gap hinders the development of universal theories and the large-scale application of MICP in complex scenarios involving soil-water interactions, such as ecological slopes and contaminated sites. Methods This study employed bibliometric analysis (VOSviewer keyword co-occurrence) to reveal the global landscape, knowledge structure, and evolutionary trends of MICP research. Furthermore, it systematically reviewed and critically analyzed recent representative application progress of MICP in two key domains: soil environments (addressing mechanical enhancement, erosion resistance, microbial screening, permeability control, agricultural improvement, and heavy metal remediation) and concrete environments (focusing on crack self-healing, environmental sustainability, crystal regulation, and process optimization). The influence mechanisms of key factors—including bacterial strains, cementation solutions, environmental parameters, and grouting strategies—on mineralization effectiveness were deeply explored. Results The study demonstrates that MICP application in soil has evolved from solely "structural improvement" to a "multi-dimensional environmental regulation" tool, effectively enhancing strength, erosion resistance, and liquefaction mitigation, and finding application in pH regulation and heavy metal immobilization. In concrete, MICP achieves self-healing through calcium carbonate precipitation within cracks, significantly restoring impermeability and durability. Core bottlenecks constraining engineering-scale application were identified: uneven precipitate distribution (influenced by flow fields, injection methods, and media heterogeneity), insufficient environmental adaptability of bacterial strains (to high alkalinity, salinity, and low temperatures), and unresolved concerns regarding long-term stability and ecological safety. Innovative approaches include utilizing auxiliary materials like bentonite to optimize permeability control and strength balance, screening and domestication of alkali-tolerant bacterial strains, developing cost-effective culture media and green alternative pathways (e.g., calcium phosphate biocement), and employing microfluidic technology to elucidate precipitation mechanisms. Conclusions This study constructed a systematic knowledge framework for MICP applications spanning soil and cement-based materials, elucidating shared principles and media-specific origins, and identifying critical challenges (precipitate uniformity, strain adaptability, long-term stability, and lack of standards). Future research should prioritize precise control of precipitate distribution, construction of stress-resistant and efficient engineered microbial libraries, long-term ecological risk assessment, synergistic integration with complementary technologies (e.g., plant-based soil stabilization, electrokinetics), and the establishment of engineering specifications. By deepening the understanding of microbial mechanisms, developing multi-scale models, and optimizing processes, MICP technology holds significant potential to play a greater role in ecological restoration, sustainable infrastructure development, and achieving carbon neutrality goals.