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Repair of reinforced concrete

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Corrosion in Reinforced Concrete Structures in the Middle East

Corrosion of reinforced concrete structures, both underground and above ground are a significant drain on the economy of most Middle Eastern countries. The majority of reinforced concrete structures in the Arabian Peninsula are chloride contaminated. As buildings and structures age, the chloride levels increase due to both chloride loading from atmospherically carried chlorides, and from capillary action which transports chloride laden ground water into concrete structures, where the water evaporates concentrating the salt above ground level. Allowing reinforced concrete structures to corrode freely results in buildings and structures that require repair or demolition due to structural failure.

One scenario of concrete damage due to corrosion happened in one of the Port in the Emirates which was constructed during 1970 and consists of pre-cast reinforced concrete beams and slabs with in situ concrete topping, supported by tubular steel piles. The first signs of deterioration were recorded after 7 years, evidenced by cracking of the lower corners of the pre-cast beams. Observing this, a series of detailed inspections were carried out.

An impressed current cathodic protection system incorporating metal oxide coated titanium anode was used to prevent further deterioration. The main advantage of impressed current cathodic protection (ICCP) lies in its much greater output capacity as compared to galvanic anode systems. Therefore, whenever corrosion protection is required for large poorly coated or bare structures, ICCP would be the system of choice. ICCP systems requires the use of an external DC power supply and metal anode in direct contact with concrete. This is achieved by embedding a durable conductive anodic overlay. This method is called reinforced concrete cathodic protection (CP).

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