Repair of the structure is necessary either to stop deterioration or to control the acceleration of degradation. The damage of a structure may be various categories in terms of their seriousness. There may be some damages which may wait and there may be some repair which could be attended as routine work. To resist further decayed and damage the repair works are done annually unless requiring early action.
After the inspection and assessment of the damage, a proper diagnosis needs to be made for finalization of the repair and its method to be adopted. Repair or maintenance of the concrete structure is done for.
Strengthening by external plastering, partial replacement and so on.
Restoring the durability by crack injection, concrete jacketing, surface coating and so on
Stoppage of water leakage by grouting surface sealing, coating. Repair may be done in a conventional way or by application of new techniques and chemicals.
Different materials are used in repair works based on technique like reinforcement, cement, aggregate, polymers, admixture, paint, bitumen and so on.
1.2:-Most common concrete repair chemicals
With the development of science and technology in general, the technology of improving the quality of construction of the concrete structure and repairing of the old damaged concrete structure and repairing of old damaged concrete structure has also improved. In the present time all shorts of construction and repair works, admixture are often used as adhesive or binding materials.
The concrete structure was considered to be non-repairable after they were damaged, the structures were pulled down. But nowadays they are being repaired and rehabilitated with the help of chemicals.
Based on their composition. chemical admixture used in construction and repair works can be broadly classified as:-
4)shotcrete/ pressure grouting
Polymer is a plastic product which is formed by the combination of monomers.”Poly” means many and “mer” means parts so, the polymer is a chemical compound where molecules are bonded together in long repeating chains.
Example: Polythene, Polyethylene, etc.
Advantages of polymer
a) Can form any shape.
b)They do not corrode.
c)Less dense so lighter.
d)Good insulator of electricity.
e)Good insulator of heat.
The disadvantage of polymer
a)Cause pollution in the ocean.
Synthetic rubber is a man-made rubber. It is produced in manufacturing plants by synthesizing it from petroleum and other minerals. It has the property of undergoing elastic deformation under stress but can also return to its previous size without permanent deformation.
Advantage of synthetic rubber
a) Low-cost material.
b)Superior low-temperature flexibility.
c)Broad market application.
d)Good abrasion resistance.
Epoxy is a unique material, which is very tough and versatile. It has several purposes ranging from concrete floor paint to steel pipeline coating to space capsule heat shields.
Advantage of epoxy
When epoxy cures, it becomes very solid and hard. Epoxy paint has such high durability that it is often used as a concrete floor plant.
Because it is hard, epoxy is easy to clean.
c)Chemical resistance capacity of epoxy is high.
d)It has high-temperature resistance.
e)It is non- toxic.
4)Shotcrete (or Grouted concrete)
The concrete in which mortar or concrete is pneumatically projected at high velocity on the backup surface is known as shotcrete or gunite.
a)Shotcrete concrete layers are very strong.
b)These types of concrete do not need construction or expansion joints.
c)It can be evenly applied on uneven surfaces.
d)It can be applied from a distance.