Enhancing Concrete Self-Healing Using Wastewater Bacteria Impregnated in Pumice Lightweight Aggregates

Self-healing concrete presents a promising solution to counter the degradation of concrete structures caused by cracks and damage. This innovative mechanism employs the concrete's capacity to autonomously repair its cracks, effectively extending the lifespan of structures and reducing maintenance costs. Particularly in regions facing water scarcity, such as the Middle East and North African countries, the utilization of wastewater holds significant importance. This study investigates the self healing abilities of wastewater bacteria infused into lightweight pumice aggregates within concrete. Wastewater contains diverse bacteria, microorganisms, and oxygen—essential components for the self-healing process. Wastewater sourced from the North Gaza Emergency Sewage Treatment (NGEST) Plant in the Gaza Strip in Palestine, was used in this research. Several concrete samples were prepared, incorporating three concentrations of impregnated pumice lightweight aggregates (10%, 15%, and 20%) to assess their self-healing performance. The investigation monitored the compressive strength and crack closure of the concrete samples at multiple stages to evaluate the wastewater's healing potential. Results indicated a notable increase in the compressive strength among the wastewater bacteria samples compared to the reference samples after 28 days of crack induction. Moreover, the crack closure in the wastewater bacteria samples was visibly evident. The rate of crack closure showed a consistent increase at 19-, 26-, and 33-days post-crack formation. These findings are promising and align with previous research that affirmed the significant potential of wastewater in enhancing self-healing properties within concrete structures.