Effect of Self Repairing Mechanism in Concrete using Biometric Materials

Cracks are easily formed in Concrete. Due to the high tensile stresses the cracks may be formed on the concrete surface. As wider the cracks endangers the strength and durability of concrete structures, So that the cost of maintenance to repair may be required. In order to enhance strength and durability cracks should be filled with bonding and inert materials. By repair and maintenance of concrete structure a high economic condition occurs. In this study the BIOMATIC MATERIALS are used to induce CaCO3. Biomatic Materials used was Bacillus subtilis bacteria. Biochemically induced calcite precipitate will help in the healing the premature cracks formed in the concrete structures. By providing self-healing agents 50% of maintenance cost is reduced. This study mainly focus on to enhance the ability of self-repairing mechanism of the concrete by the help of formation of calcite precipitation. It is also an attempt to reduce the burden of frequent maintenance and manual repair works thus resulting in increase of lifetime of the concrete structures. Since the crack formation is major threat for the concrete structures this will study will help to overcome those catastrophic situations. Hence by using this innovative technique of cracking healing in the concrete structures the strength and durability will be increased compared to the conventional concrete.


1.INTRODUCTION
Concrete is a material which is the most widely used in construction of the buildings in the world.Natural processes such as weathering, faults, land subsidence, earthquakes, and human activities are the main reasons for creating cracks in concrete structures.The common problem found in buildings is Crack. Crack may be due to many reasons. Some reasons are Expansion and shrinkage of concrete due to temperature change in the environment, Settlement of structure, Due to heavy load applied, Due to loss of water from concrete surface when shrinkage occurs, Insufficient vibration at the time of laying the concrete, Improper cover, High water cement ratio to make the concrete workable, Due to corrosion of reinforcement steel, Many mixtures with rapid setting. Cracks makes the Concrete to look unpleasant becauseit forms an open pathway to the reinforcement and can lead to durability problems like corrosion of the steel bars.These cracks should be repaired because they can reduce the service lifetime of the structure.In case of historical monuments, cracks makes the structure to appear spoilt.Remediation of existing cracks has been subject of research for many years. The products such as structural epoxy, resins, epoxy mortar, and other synthetic mixtures are used as filling material for cracks in concrete but they are not environmentally friendly not even safe for human health.Here are some four possible mechanisms given for self-healing of concrete which are as follows • Formation of material like calcite • Blocking of the path by sedimentation of Particles • Continued hydration of cement particles • Swelling of the surrounding cement matrix.

SELF-HEALING CONCRETE
Self-healing concrete consists of a conventional mix with bacteria incorporated into the concrete and calcium lactate to provide food to support those bacteria when they become active. The bacteria which is feeding on the provided food source heals the damage done and also reduces the amount of damage sustained by the concrete structure in place.Special type of bacteria's known as

SAMPLE COLLECTION
To attain the goals, materials were collected from various sources. Material collection is the basic and important step in any project. Yet the material used in this study should not cause any damage to the environment. For the selfhealing concrete the specimens are prepared in various process. The samples are micro-organisms, chemicals for healing agent, materials used for conventional concrete.

CASTING AND CURING
The cube and the cylinder specimen are casted for conventional and self-healing concrete. The mix proportion is M20 as per IS 10262-2009. After 24 hours of casting the specimens are demoulded, these specimens are immersed into water for curing process for 28 days. After the curing the specimens are subjected to testing.    the stored water will not be leaked as they heal early age cracks. ✓ They are also used in constructing underground retaining structures for hazardous wastes. ✓ It reduces Permeability of the concrete. ✓ It increases Durability of the concrete.

ADVANTAGES
✓ Reduction in permeability of concrete. ✓ It increases durability of concrete. ✓ It is pollution free, eco-friendly and natural. ✓ Lower repair and maintenance cost. ✓ Applicable to existing buildings in the form of spray.

DISADVANTAGES
✓ Initial cost is higher. ✓ Non-availability of IS codes for providing bacteria.

APPLICATIONS
✓ Repairing of monuments. ✓ Healing of concrete cracks. ✓ Used in water retaining structures. ✓ Used in low cost durable roads.