Mechanical and Durability Characteristics of Bacterial Concrete

Concrete is the most widely used construction material. Micro cracks which occur on the concrete structures can reduce the strength of the structure. Prolonged exposure of these cracks to the stresses and external environment can increase the damage and can even be lethal. Bacterial concrete is a solution for the micro cracks. Bacterial concrete has a self healing property by which it can repair cracks upto 0.5 mm width. An investigation is conducted to study changes in the compressive strength, split tensile strength and flexural strength of concrete by the addition of bacteria. Concrete specimens with bacterial concentrations of 0, 15, 30 and 45 ml mixed with equal amount of calcium chloride are used. When crack occurs, and water passes through the cracks, the bacteria present in the concrete matrix starts to feed on the calcium chloride by consuming oxygen and converts the calcium chloride into the insoluble calcium carbonate (limestone). And this limestone heals the cracks. Durability of the bacterial concrete is also studied and compared with normal concrete by analyzing the water absorption and reaction to sulphate and chloride ions.