Micro Structural Analysis of Bacterial Concrete

Abstract

Concrete is the most widely used construction material in the world. Despite its different qualities in the construction, it has many limitations. It is weak in tension, has limited ductility and less resistance to cracking. The primary reason for the cracking of concrete can be attributed to porosity in texture (microscopic level) of structural members which allows moisture and water to seep into the concrete members and hence, leads to corrosion of steel reinforcements. Although, a variety of waterproofing agents and surface treatments like the water repellants such as silanes or siloxanes are available which are used to enhance the durability of concrete structure, they suffer from various limitations like incompatibility, susceptibility to UV radiations and are also expensive. A technique was proposed in remediating cracks and fissures in concrete by microbiologically inducing calcite precipitation. Microbes like Bacillus pasteurii, can induce the precipitates of calcite. It can increase the durability performance of concrete with increase in the concentration of bacteria. Moreover, this calcite layer can also improve the impermeability of the specimen, thus increasing its resistance to alkaline, sulphate and freeze-thaw attack.