Causes of Deterioration
a) Design and construction Flows
Design of concrete structures governs the performance of concrete structures. Well-designed and detailed concrete structure will show less deterioration in comparison with poorly designed and detailed concrete, in this similar condition. The beam-column joints are particularly probe to defective concrete, if detailing and placing of reinforcement is not done properly.
b) Environmental effects
Micro-cracks present in the concrete are the source of access of moisture and atmospheric carbon-di-oxide into the concrete, which attack reinforcement and react with various ingredients of concrete. In aggressive environment, concrete structures will deteriorate faster and strength/life of concrete structures will be severely reduced.
c) Usage of poor Quality Material
Quality of materials to be used in construction, should be ensured by means of various tests, as specified in the IS codes. Alkali-aggregate and Sulphate attack results in early deterioration. Clayed materials in the fine aggregates may weaken the mortar-aggregate bond, and reduce the strength.
d) Quality of Supervision
Construction work should be carried out as per the specifications. Adherence to specified water-cement ratio controls strength, permeability and durability of concrete. Insufficient vibration may result in porous and honey-combed concrete, whereas excess vibration may cause segregation.
e) Deterioration due to Corrosion
ü Spalling of concrete cover
ü Cracks parallel to the reinforcement
ü Spalling at edges
ü Swelling of concrete