Self-Healing Concrete using Encapsulated Bacterial Spores in a Simulated Hot Subtropical Climate

Bacterial concrete has become one of the most promising self-healing alternatives due to its capability to seal crack widths through microbial induced calcite precipitation (MICP). In this study, two bacterial strains were embedded at varying dosages (by weight of cement) in concrete. Beam specimens were used to identify the maximum crack-sealing efficiency, while cylinder samples were used to determine their effects on the intrinsic mechanical properties, as well as its stiffness recovery over time after inducing damage. The concrete specimens were cured in wet-dry cycles to determine their feasibility in Region 6. The results showed that the specimen groups with the highest calcium alginate concentrations (including the control specimens with embedded alginate beads but no bacteria) resulted in higher increases in stiffness recovery. Similarly, the beam samples containing alginate beads (also including the Control 3%C specimen group) had superior crack-healing efficiencies than the control samples without alginate beads (Control NC). This was attributed to the fact that the alginate beads act as a reservoir that can further enhance the autogenous healing capability of concrete. Overall, further research is recommended to verify whether the promising results reported in the literature (relating to self-healing mortar) correlate with concrete proportionally. In addition, there is a need to explore the factors that can maximize the self-healing mechanism of bio concrete through MICP, whether an alternative encapsulation mechanism, nutrient selection, curing regime, or bacterial strain is desired.Tran-SET Project No. 18CLSU0