Methods of Rebar Protection and Repair Techniques on Concrete Structures

The major factors leading to the deterioration of reinforced concrete are poor construction practice and the environment. Rebar corrosion is widely regarded as the most common cause of deterioration and premature failure of reinforced concrete (RC) structures These factors are interrelated, for example inadequate depth of cover to rebars, or excessively porous concrete, may allow penetration of atmospheric contaminants such as carbon dioxide or chlorides to reach the steel. In the presence of oxygen and moisture, this will cause it to corrode. Sooner or later, cracking and spalling of the concrete cover will occur as the expanding rust products build up bursting stresses around the rebars. It is therefore of great importance in aggressive environments to provide a sufficient cover of high quality concrete to all embedded steel. This is particularly so in coastal and marine structures, where chloride contamination from wind-borne salt spray can be severe. The primary methods commonly used to treat concrete which is suffering, or threatened by corrosion damage to embedded steel are patch repairs or partial rebuild, Protective coatings, Cathodic protection. Cathodic protection has become accepted and widely used as a means of halting corrosion of steel in deteriorating reinforced and prestressed concrete structures. The advantage of Cathodic Cathodic Protection exhibits long-term economical advantages when discounted over the design life of the system. In many cases, the first cost may be less than a conventional patch repair, with a life four to five times longer. It is also recognized as a means of prevention of corrosion damage in new structures, where for a small percentage of the capital cost the design life expectations can be met without repeated and expensive repairs