Effect of Using Magnesium Acetate on the Self-Healing Efficiency of Hydrogel-Encapsulated Bacteria in Concrete

Microbial induced calcite precipitation (MICP) is a promising pathway in self-healing concrete due to its capability to seal cracks. In the present research study, Bacillus pseudiformus was selected as the bacterial strain and encapsulated with nutrients in hydrogel beads that were further added to a mortar mix. A combination of magnesium acetate and yeast extract were implemented as the nutrients and evaluated at different dosages. Flexural strength tests were performed on the specimens 28 days after casting in order to induce cracking. Once the crack was induced the specimens were subjected to 28 days of wet/dry cycles and the corresponding crack width was monitored. A second flexural strength test was performed in order to determine the strength recovery at the end of the cycles. Furthermore, the self-healing efficiency was obtained from the crack widths, revealing that the specimens with a larger nutrient and cell concentration displayed the best results.