Ranking Bacteria for Carbon Capture and Self-Healing in Concrete: Performance, Encapsulation, and Sustainability
Ajitanshu Vedrtnam, Kishor Kalauni, Martin T. Palou
Abstract
Concrete production contributes nearly 8% of the global CO2 emissions, making carbon capture in construction materials a critical environmental priority. While microbial self-healing concrete has shown promise in repairing structural cracks, its potential to serve as a carbon-negative material through atmospheric CO2 sequestration remains underutilized. This interdisciplinary review—designed for materials scientists, civil engineers, and environmental technologists—systematically evaluates bacterial candidates for their application in self-healing, carbon-capturing concrete. Bacteria are ranked according to their efficiency in capturing CO2 through both direct mechanisms (e.g., photosynthetic fixation by cyanobacteria) and indirect pathways (e.g., ureolysis-driven calcium carbonate precipitation). The assessment also considers microbial survivability in high-alkalinity concrete environments, the effectiveness of encapsulation strategies in enhancing bacterial viability and function over time, and sustainability metrics such as those derived from life cycle assessment (LCA) analyses. The findings highlight Bacillus sphaericus and Sporosarcina pasteurii as high-performing species in terms of rapid mineralization and durability, while encapsulation significantly improves the long-term viability for species like Paenibacillus mucilaginosus and Synechococcus. Notably, Bacillus sphaericus and Sporosarcina pasteurii exhibit carbonate precipitation rates of 75–100 mg CaCO3/g biomass and enable crack closure of up to 0.97 mm within 8 weeks. The proposed bacterial ranking framework, paired with performance data and environmental modeling, provides a foundation for the advancement of scalable, carbon-negative concrete solutions.