Concrete is a material which is the most widely used building material in the world.
Natural processes such as weathering, faults, land subsidence, earthquakes, and human activities creates cracks in concrete structures.
Concrete expands and shrinks with changes in moisture and temperature and this tendency to shrink and expands causes cracks in concrete.
We do not like cracks in concrete because cracks form 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 life of structure.
In case of historical monuments cracks spoils the appearance of structure.
Remediation of already existing cracks has been subject of research for many years.
The various product such as structural epoxy, resins, epoxy mortar, and other synthetic mixtures are used as filling material 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 under :
1.) Formation of material like calcite
2.) Blocking of the path by sedimentation of Particles
3.) Continued hydration of cement particles
4.) Swelling of the surrounding cement matrix.