The utilization of traditional supplementary cementitious materials (SCMs) has become more intense in the concrete industry due to their better long-term properties. This research evaluates the fresh and hardened properties of concrete that was developed using a high amount of recycled aggregate (RA) incorporated with sustainable SCMs. Rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) were used as SCMs at 10%, 20% and 30% cement replacement levels to investigate their positive role in the performance of RA concrete. The results showed that the 10% replacement level of cement by RHA produced the highest strength at all ages tested. Although POFA and POCP were found to negatively affect the strengths at an early age, the hardened properties showed improvement after a relatively long curing time of 90 days. In addition, the targeted compressive strength of 30 MPa was achieved by using SCMs at levels up to 30%. Overall, the sustainable SCMs can reduce the quantity of cement required for concrete production, as well as reduce the conventional cement with the industrial by-products, which are considered as waste materials; thus, the concrete produced using up to 30% of SCMs as a replacement for cement could be considered as more environmentally-friendly concrete.

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.