| "After completion of the construction of concrete structures, chloride ion will penetrate into the concrete and causd damage, this phenomenon is known as salt-attack. Photo- 1 shows the pre-tensioning concrete girder damaged by salt-attack. The quantity and the depth of penetration of chloride ion depend on the environment and the age of the concrete structures. For some case, the chloride ion may reach to the depth of the prestressing tendons. In repair of prestressed concrete structure which were damaged by salt-attack, it was uncommon to remove all the parts of concrete in which chloride ions were, in stead, only the parts which were a few centimetres deeper than the reinforcing bar and were damaged due to the expansion of the corrosive reinforcing bar were removed. For this reason, even after the repairing, deterioration of concrete may be developed again due to the occurrence of macro-cell phenomenon between the part repaired and the part untouched." |
