State-of-the-art review on advancements of eco-friendly bacterial-infused self-healing concrete for sustainable constructions

In urban areas, construction projects and activities have been flourishing due to rapid urbanization. As a result, there is a growing demand for building materials that can withstand the test of time. Concrete is an important material in construction and is widely used around the world. However, traditional concrete is not without its flaws. Cracks are inevitable, and when water and moisture seep into these cracks, they can cause further deterioration. By harnessing the power of biomineralization, bacterial concrete aims to enhance the performance and durability of concrete structures. Bacterial self-healing concrete works by introducing specific bacteria into the concrete mix by methods including injection, mixing and capsules. The choice of bacteria is based on their ability to survive in alkaline environments, such as B. pasteurii, Bacillus cereus, Bacillus megaterium, Bacillus subtilis, and B. spharicus. Bacteria enhance structural characteristics such as tensile strength, water permeability, stress-strain behavior, durability, compressive strength, costeffectiveness, healing capacity, and environmental impact. A novel self-repair method involves inducing bacterial calcite precipitation within concrete mixtures to heal cracks. This technique utilizes bacterial mineralization, achieved by breaking down urea and calcium to generate calcium carbonate (CaCO3), which fills the cracks with widths ranging from 0.05 to 0.1 mm. Various factors indicate that the load-bearing capability of self-healing concrete has risen by as much as 21 %, accompanied by alterations in fracture patterns and deflection, characterized by a higher crack density and reduced width. Moreover, beam ductility has been enhanced by up to 45 %, along with a minimum increase in energy absorption of 100 %. Therefore, this paper aims to elucidate bacterial concrete, categorize microorganisms, explore the functionality of bio concrete as a repair material and examine its applications through a literature review.