Microbial induced calcite precipitation for improving low-cohesive soil: mechanisms, methods and macroscopic properties

Abstract Microbial-induced carbonate precipitation (MICP) has emerged as a promising eco-friendly and cost-effective alternative for improving the strength and stability of low-cohesion soils. This review provides an in-depth analysis of the microscopic mechanisms, implementation methods, and macroscopic properties of MICP in soil enhancement. The biogeochemical processes underlying MICP, including urea hydrolysis, denitrification, sulfate reduction, photosynthesis, and iron reduction, are discussed in detail. Various MICP implementation methods, such as two-phase treatment, one-phase treatment, and ex-situ mixing, are reviewed, highlighting their respective advantages and limitations in reinforcing low-cohesion soils. The review also addresses the performance of MICP-treated soils, including improvements in strength, stiffness, permeability, and durability. Furthermore, the key challenges and future prospects for microbial soil reinforcement technologies are summarized. Future research should focus on optimizing nutrient supply, enhancing bacterial retention and activity, controlling the crystallization process, conducting pilot projects, and reducing treatment costs. These efforts are crucial for advancing the practical application of MICP in sustainable infrastructure construction. This review aims to advance the understanding of MICP and its potential for sustainable soil improvement, offering valuable insights for geotechnical engineers.