Self-healing concrete is an artificial or synthetically made material with an inherent ability to repair damage on its own without any external diagnosis or human intervention.
This can be a special kind of concrete that was invented by a group of microbiology researchers under the Henk Jonkers.
Self-healing concrete is often known as “Bio Concrete” or “Bacterial Concrete”.
It is specifically designed to increase the life span of durability of concrete structure by self-healing action of that concrete.
Introduction to Self healing concrete:
Self-healing concrete is concrete that cures itself when exposed to air and water, it produces lime on the outer layer of concrete.
In most conventional concrete mixtures, 20–30% of cement is left un-hydrated.
If cracking of concrete occurs unreacted cement, grains may become exposed with moisture entering the crack.
In that case, the hydration process can resume and the hydration products can fill and fix the crack.
Objectives of self healing concrete:
- To heal cracks by bacterial precipitation.
- To investigate the effect of Bacillus species bacteria in gaining strength in contrast to conventional concrete.
- Enhancing the durability and compressive strength of concrete.
- Efficient use of bio concrete in the marine structure.
- The formation of cracks in concrete structures is unavoidable because of the deterioration of its service life because of various loads and non-load components.
- Therefore, repair and maintenance operations are required to prevent cracks from spreading and reduce the service life of the structures.
- The cracked area may be difficult to access and may need to be rebuilt.
- It is an eco-friendly technique, which can be used to prevent metals from deteriorating.
Advantages of Self healing concrete:
- This concrete has comparatively much lower permeability, greater durability and stress carrying capacity than conventional concrete.
- It can be applied to existing buildings in the form of spray which can reduce the overall repair and maintenance costs of the buildings.
- This is an environmentally friendly technique because the carbon dioxide produced is prevented due to the low use of concrete.
- SHC is a more effective shock-absorber that protects it during earthquakes because it has a polymer membrane on its surface.
- It can operate at internal levels which means that the smallest cracks can be reached.
- Un-hydrated cement that does not contribute to strong participation can be used.
- Helps to fill the crack.
- Improvement in the compressive strength of concrete.
- Better resistance to freeze-melting attack reduction.
- Permeability reduction of concrete.
- Corrosion reduction of reinforced concrete.
- Helps reduce maintenance and repair.
Disadvantages of self healing concrete:
- The cost of self-healing concrete is double that of conventional concrete.
- The growth of any bacteria is not good in any atmosphere media.
- Calcite precipitation investigations are expensive.
- Skilled labor is required.
- In this reaction mechanism, the 2 ammonium ions are generated simultaneously for every carbonate ion, which can lead to extreme environmental nitrogen load.
- The matrix of concrete changes and reduces the amount of mixing thus reducing the strength of the concrete.
- Power boost is a fairly slow process.
Applications of Self healing concrete:
- It can be actively used in the case of roads to reduce traffic jams.
- Also used by the oil and gas industries, preventing small cracks from spreading.
- It can be used to strengthen both existing and new types of structural building.
- It is effective in areas where buildings undergo freezing and thawing.
- This can prove to be economical in case of irrigation works, dams etc. which are directly in contact with water.
- This concrete can be used for sectors such as tunnel-linings, structural basement walls, highways, bridges, concrete floors, and marine structures.
- It is new technology that can give way to sustainable roads.
- In high strength buildings with more bearing capacity.
Self-healing concrete have capabilities to increased durability of various building materials, giving them higher strength with greater bearing capacity and extending the building life.