Behaviour of Concrete under the Influence of Bacillus Subtilis as a Self Healing Agent

As we know Concrete is a majorconstruction material in the world but due to its low level tensile strength and other factors of nature, forming of cracks in concrete is a very common problem and without proper and quick treatment, cracks in concrete structures begins to expand more and ultimately lead to failure of structure. Cracks in concrete also develop an open passage to the reinforcement bars leading leads to corroded steel bars, which leads to durability problems of structure. For many years now proper healing of concrete cracks is prime object of investigation. In order to vanish this huge problem, an efficient technique has been introduced in fixing cracks with environmental friendly biological process that is also known as self-healing process based on the use of smart concrete which is generally known as Self-healing concrete. Hence principal objective of the research is to develop self-healing con-crete by incorporation of bacteria as self-healing agent. An experimental program is carried out to examine the self-healing mechanism by evaluation of bacterial influence and its effect on the concrete. In the current study, bacteria termed Bacillus Subtilis was incorporated with concrete in different concen-trations. Evaluation of healing effect was worked out by comparing compressive strength, water absorption content, Ultrasonic Pulse Velocity (UPV) of bacterial concrete to conventional concrete. Specimen were experimented for compressive strength at the ages of week, month and two months of curing. Other tests like Slump cone test, UPV test, water absorption tests were also conducted. Finally, healing of cracks was visualized at the age of 60 days and analyzed using Scanning Electron Microscope (SEM) studies. The results pointed that that a significant amount of self-healing of cracks was achieved and use of bacteria named Bacillus Subtilis proved to be a better choice. Hence we concluded that the stiffness, workability, compressive strength and dura-bility of concrete gets increased with the bacteria inclusion in the concrete. Also it is evident the concrete cracks have been healed by the formation of limestone (CaCO3) which is observed using Scanning Electron Microscopy (SEM).