Various Methods of Encapsulation Biomaterials in Self‐Healing Concrete: A Review

Concrete is known for its inherent vulnerability to cracking, which can be attributed to factors like temperature fluctuations, changes in moisture levels, and cyclic loading. In order to facilitate crack healing, a variety of living and non‐living agents have been employed. Among these agents, bacteria, both ureolytic and non‐ureolytic, have gained significant attention due to their versatility in different applications. Incorporating bacteria into concrete can be achieved through various methods, such as direct addition or embedding within cargos at different scales, ranging from micro to macro levels. The encapsulation of healing materials poses a significant challenge in the sustainable advancement of such concretes. This paper aims to explore 16 encapsulation techniques for transferring bio‐materials to the concrete. In the initial phase, a detailed explanation was provided for the capsule production process. Eventually, the selection of optimal techniques for encapsulating biomaterials was made based on expert opinions and scientific literature. Each method was evaluated according to specific criteria such as mechanical properties, healing effectiveness, complexity, cost, environmental impact, and durability. A score ranging from 1 to 3 was assigned for each criterion, followed by the implementation of weighted averaging to ascertain the importance of each criterion in relation to the encapsulation methods. The highest‐rated encapsulation method, achieving an average score of 0.48, is the lightweight aggregate (LWA) encapsulation technique. The second position, with a score of 0.45, pertains to slug and chitosan capsules, while the third rank, with a score of 0.43, is attributed to the calcium sulfoaluminate encapsulation.