Bacterial Concrete

Concrete is the most used, strong and durable building material in the world. It is known that Concrete has a large load bearing capacity for compression load but it is weak in tension. The steel reinforcement bars (rebars) are embedded in concrete to impart tension bearing capacity. The reinforcement takes over the load when concrete structure is subjected to tension and prevents deformation, deterioration (i.e. crack development) and failure. The concrete, on the other hand, prevents corrosion of steel bars, protecting them from attacks of deteriorating agents from the environment, such as chlorides, sulphates, carbon dioxide. These deteriorating agents are responsible for causing cracks, make concrete more permeable and ultimately result in corrosion of reinforcement. The lower the permeability the higher is the durability of concrete. Thus to make the structures durable, either the cracks that have formed are repaired later or in the design phase extra reinforcement is placed in the structure to ensure minimum deformation under tension so that crack widths stay within a certain limit. This extra reinforcement is then only needed for durability reasons (to keep the crack widths small) and not for structural capacity. The extra steel is not desirable, keeping in view the current steel prices. It is not desirable from the sustainability considerations also. Thus a reliable method to automatically repair cracks in concrete will increase and ensure durability and functionality of concrete structures substantially. On the other hand, it will reduce the cost extra reinforcement. The bacterial concrete helps in doing that.