Why does Concrete need Repairs?
There are many factors which lead to the need of repairs such as:
· Corrosion of reinforcement due to carbonation, chlorides
· Effects of Sulphates
· Alkali silica reaction
· Environmental pollution
· De-icing salts
· Acid rains
· Freeze thaw cycles
· Abrasion or erosion from wind or water borne agents
· Plants or micro organisms
· Physical settlement
· Chemical attack by aggressive chemicals, in industrial or marine environment sewerage or even soft water.
Also the deterioration gets aggravated due to errors/mistakes/ poor workmanship during construction such as:
· Higher w/c ratio
· Honeycombs and compaction voids
· Bleeding and segregation
· Plastic shrinkage & hardening stage shrinkage cracks
· Inadequate or no curing
· Insufficient concrete cover
· Cast-in chlorides from contaminated water/aggregates/ /admixtures
· Inadequate or excessive vibration during concreting
· Shutter work or reinforcement movement during placement of concrete
Generally, concrete structure requires repairs in the two cases– New construction and during the service life. Repairs in the new construction require a different approach then the repairs during service life and we shall deal one by one for better understanding. The repairs during service life have more steps and we will deal this first. The repairs during service life arise due to certain deterioration taken place and understanding of the same is very vital in the design of the repair solution.