Expanded perlite immobilization enhances long-term survival and mineralization activity of microbial spores in cementitious environments

Microbially induced carbonate precipitation (MICP) provides a sustainable approach for the autonomous repair of microcracks in concrete. However, its practical application is limited by the poor long-term survival of microorganisms in the highly alkaline environment of cement matrices. This study used expanded perlite as an immobilization carrier to systematically investigate the effects of pH, temperature, and aging on microbial spore survival. Under non-immobilized conditions, acclimatized spores showed optimal long-term activity at pH = 10 and 0°C. After 180 days, the spore survival rate reached 12.31%, and urease activity achieved 0.74 mmol/(L·min)-approximately twice and nine times higher, respectively, than those recorded at 30°C over the same period. Although environmental factors reduced microbial mineralization capacity under immobilized conditions, mineral precipitation stabilized at around 5.60 g, representing a 28-fold increase compared to non-immobilized results over the same duration. These findings confirm that the carrier effectively alleviates the adverse effects of high alkalinity and temperature variations. The expanded perlite-based immobilization strategy significantly extended microbial service life, improved remediation efficiency, enhanced engineering feasibility, and reduced long-term maintenance costs. This research offers critical technical support for the development of durable and high-efficiency self-healing concrete systems.IMPORTANCEMicrobially induced carbonate precipitation (MICP) has gained significant attention as a promising technology in architecture and civil engineering. However, the understanding of microbial long-term activity and mineralization capacity within cement-based materials remains limited. This study investigated the influence of environmental factors on microbial spore survival in such materials by monitoring key indicators, including microbial concentration, urease activity, and mineral precipitation. Furthermore, it identified specific environmental conditions that support prolonged microbial viability. The use of expanded perlite as a carrier material aimed to mitigate external environmental stresses on microorganisms, thereby extending their mineralization capability over extended periods. These findings provide a scientific basis for the rational design of microbially mediated self-healing concrete systems.