Microbially-Induced-Calcite-Precipitation (MICP): A biotechnological approach to enhance the durability of concrete using Bacillus pasteurii and Bacillus sphaericus

Developing bio-based self-healing concrete aims to minimize durability problems related to cracking. In this study, MICP was used as a smart and eco-friendly approach to produce bio-based durable materials. Bacillus pasteurii (BP) and Bacillus sphaericus (BS) were added into mortar mixtures with 0.25% and 0.5% cement weight. All treated samples exhibited a significant decline in water uptake, capillary permeability, and volume of permeable voids, as compared to control with no bacteria. All treated samples showed significant increase in compressive strength by 28–50%, after 28 days of curing. At the age of 120 days, the flexural strength of all treated samples was significantly increased by 19.29–65.94%. SEM imaging and EDAX confirmed that treated samples were denser with less voids due to MICP. DTA verified that the calcite amount and the crystallinity degree were improved in treated samples. Load deflection of bacterial Reinforced-Laminates had less deformation than control. Reloaded bacterial Reinforced-Laminates exhibited excellent restoration of physico-mechanical properties and performance, after 28, 90, and 120 days, confirming the healing process. Microbial self-healing is an innovative approach for continuous repair of micro-cracks in concrete, improving its durability, thus can reduce the maintenance costs.