Dissolution and recrystallization behavior of microbially induced calcium carbonate: influencing factors, kinetics and cementation effect

Microbially induced calcium carbonate precipitation (MICP) is a nature-based biomineralization method with significant potential in geotechnical engineering. Despite the extensive previous studies on this technology, the stability of calcium carbonate crystals formed during the MICP process and its impact on cementation effectiveness remains unclear. This study investigates the effects of varying curing conditions and durations on the stability of microbially induced calcium carbonate crystals. Throughout the curing period, pH levels of the solutions and the mass of calcium carbonate samples were monitored. Crystal morphology, crystalline composition, and cementation properties were examined using scanning electron microscopy, X-ray diffraction, and ultrasonic oscillation tests. The findings reveal that vaterite remained stable in MICP or bacterial solution but quickly dissolved in deionized water. While most vaterite underwent dissolution and recrystallization within the first day of curing, the presence of organic matter in the crystals led to 10-20% of the vaterite remaining undissolved after 28 days. The dissolution of vaterite tended to promote the growth of pre-existing calcite polymorph rather than forming new ones. Extended curing periods in deionized water increased the proportion of dissolved vaterite, resulting in higher calcite content and enhanced cementation properties, which provides new insights for optimizing MICP applications in geotechnical engineering.