Niklas Erdmann

• Microbiologically induced calcium carbonate precipitation (MICP) is an emerging technology with applications in geotechnical engineering and construction. This dissertation investigates the ureolytic MICP process, focusing on optimizing its efficiency and applicability for biocementation of granular materials such as sand. The study systematically examines key influencing factors, biomass concentration, temperature, the composition of the cementation solution and particle size distribution. Experiments were conducted using the ureolytic bacterium Sporosarcina pasteurii to induce calcium carbonate precipitation under controlled conditions. The research explores the kinetics of ureolysis and its impact on the efficiency of calcium carbonate precipitation. A particular focus is placed on the influence of sand particle size on the mechanical properties and pore structure of MICP-treated sand. Variations in particle size affect the distribution and bonding of calcium carbonate, impacting overall compressive strength and durability. Following this, the study employs response surface methodology (RSM) to optimize compressive strength by systematically varying and analyzing multiple parameters to enhance biocementation outcomes. Despite the advantages of MICP as a sustainable alternative to conventional cement-based materials, challenges remain. The production of ammonium as a by-product and the energy-intensive synthesis of urea present environmental concerns that require further optimization. This work contributes to a deeper understanding of MICP and provides a framework for improving its efficiency and scalability in construction and soil stabilization applications. The findings highlight the potential of MICP to enhance the durability of built environments while identifying key areas for future research in microbial mineralization processes.