## 13 Conclusions  
This review article analyzed and compared various relevant studies on sundry smart bio-agents-activated sustainable self-healing cementitious materials. In addition, many state-of-the-art tests and methods used to assess the self-healing efficiency of such smart bio-materials beneficial for the green construction were underscored. An all-inclusive overview of the appropriate literature on smart bio-materials-based self-healing concrete was performed in this study, which allowed us to draw the following conclusions:  
1. The design of bio-materials-based self-healing concretes with improved performance and endurance useful for several applications is a new avenue in the smart concrete-enabled construction industry. 2. Systematic integration of self-healing smart materials for both construction information and physical indices, such as mechanical strength and durability, are essential to enhance their functionality via the autonomous self-healing. The self-healing efficacy of such functional materials is characterized by their capacity to lower the cracks' widths, lengths, and depths when inspected visually. 3. Generally, the recovery tests for the strength characteristics are conducted to assess the self-healing efficacy of the cited materials. Various tests at the scale of macro- and micro-structures have been performed to achieve the most reliable outcomes regarding the self-healing efficiency of the materials. However, tests at the nanoscale remain deficient. 4. Inclusion of bacteria as a self-healing agent in the cementitious matrices was shown to enhance the compressive strength recovery of concrete. Furthermore, the combination of fibers and bacteria in the self-healing materials was observed to improve their flexural and splitting tensile strengths. 5. Regarding the durability, uses of bacteria in the concrete structures was found to decrease the water permeability and chloride ions penetrability. Some studies disclosed that the use of bacteria in the concrete structures provide improved performance of cracks' healing and excellent mechanical strengths. 6. It was asserted that microbial concrete, owing to its cost-effectiveness and environmental friendliness, may be a viable substitute to the traditional cement-based concrete. Such concrete can potentially be used as high-performance concrete sealant, leading to durability enhancement of the sustainable construction materials. Presently, the cost of bio-agents incorporation into concrete is relatively high. To lower the overall cost, strategies such as the reduction in the bio-agents production cost and self-healing activity design with durability for the commercial viability of the self-repairing products were adopted. Such materials are expected to perform well under multiple loading cycles and harsh environmental conditions. 7. Capsules design and insertion in concrete are the vital components to achieve improved self-healing traits. Recent findings indicated that the time taken for the closure of cracks in the bio-agents-activated self-healing process under suitable curing conditions is too long, characteristically spanning over two to three weeks. 8. Self-healing smart concretes are characterized by many significant traits, such as producing less pollution, eco-efficiency, and elevated durability performance in harsh environments. These properties make them effective sustainable materials in the construction industries. 9. With continued development and seamless integration of self-healing materials into modern-day applications, it is set to open a new era of enhanced consumer experience, infrastructures maintenance and environmental management, as well as countless unprecedented and unique applications. 10. Research is a continuous process in human development; it is generally believed that today's research is tomorrow's wealth. Therefore, the effect of different types of concretes and their pH values on the performance of the smart biomaterials-based self-healing are highly recommended for future studies. **Author Contributions:** G.F.H.