Aerobic non-ureolytic bacteria-based self-healing cementitious composites: A comprehensive review

The use of bacteria for self-healing cement-based materials has shown great potential in recent years. Microbially induced calcium carbonate precipitation (MICP) is a novel technology that relies on the metabolic activity of bacteria, principally from the genus Bacillus and close relatives, to precipitate calcium carbonate (CaCO3) inside the cracks to heal them. Among the different bacteria that can be used for this purpose, aerobic non-ureolytic bacteria have shown promising results to improve healing efficiencies and engineering properties of self-healing cementitious composites in a more sustainable way. Unfortunately, research results involving these specific bacteria species are scattered throughout the literature. Therefore, this review aims to present in one place the state-of-the-art knowledge relevant to the development of self-healing cementitious composites that rely on aerobic non-ureolytic bacteria. In this review, the most recent advances regarding the various aerobic non-ureolytic bacteria species normally used (e.g., B. cohnii, B. pseudofirmus, etc.), the methods for embedding these bacteria, the effects of these bacteria on the healing performance of cementitious composites, the results from various outdoors trials and the economic feasibility of these systems are reported, and the principal findings discussed and summarised at the end of each section. Finally, research gaps and future research work are identified and presented in the last section.