Corrosion of reinforcing steels at cracks in concrete

The extent of corrosion at cracks and the factors which have the greatest influence on corrosion of reinforcements of concrete bridges were studied. The corrosion grade of reinforcing steels at cracks was visually estimated and the depth and width of a corroded area was measured. The factors chosen to explain corrosion were: the age of a bridge, the thickness of a protective concrete cover, the crack width, the carbonation depth at crack and at uncracked concrete surfaces, the pH value of concrete in the vicinity of reinforcements as well as the strength and chloride content of concrete. The correlation of the corrosion grade with the pH and chloride content of concrete was indicated. The corrosion grade was also proved to be dependent on the difference between the thickness of the protective concrete cover and depth of the carbonated zone at the crack.