Impact of Bio-Carrier Immobilized with Marine Bacteria on Self-Healing Performance of Cement-Based Materials

The present study evaluated the self-healing efficiency and mechanical properties of mortar specimens incorporating a bio-carrier as a self-healing agent. The bio-carrier was produced by immobilizing ureolytic bacteria isolated from seawater in bottom ash, followed by surface coating with cement powder to prevent loss of nutrients during the mixing process. Five types of specimens were prepared with two methods of incorporating bacteria, and were water cured for 28 days. To investigate the healing ratio, the specimens with predefined cracks were treated by applying a wet–dry cycle in three different conditions, i.e., seawater, tap water, and air for 28 days. In addition, a compression test and a mercury intrusion porosimetry analysis of the specimens were performed to evaluate their physico-mechanical properties. The obtained results showed that the specimen incorporating the bio-carrier had higher compressive strength than the specimen incorporating vegetative cells. Furthermore, the highest healing ratio was observed in specimens incorporating the bio-carrier. This phenomenon could be ascribed by the enhanced bacterial viability by the bio-carrier.