Critical Corrosion Amount to Cause Cracking of Reinforced Concrete Structures

Abstract

Tensile stresses can be caused in surrounding concrete by steel bar corrosion in concrete through expansion pressure induction. Serious concrete cover cracking may result, which greatly affects concrete structure serviceability and durability. Realistic determination of the critical corrosion amount (CCA) that causes concrete cover cracking initiation is therefore necessary. The study's purpose is exploration and determination of CCA causing concrete cover surface cracking. A comprehensive experimental study was performed to this end. Concrete strength and cover thickness were among major test variables. The concrete steel bar corrosion tests have been conducted, and concrete cover surface strains have been measured according to various steel corrosion amounts. The present test results determined the CCA, which caused cracking initiation on concrete cover surface. It was seen that with an increase in concrete cover thickness, there was a great increase in CCA. CCA is indicated by the present study to increase approximately proportionately to concrete cover thickness square. CCA is also affected by concrete strength. The study shows that with a compressive strength increase, there is also a CCA increase, especially in the case of normally used large and medium cover thicknesses, that, when a cover thickness in actual concrete structures exceeds 40 mm (1.6 in.c) The study found that compressive strength effect on CCA is not large for small cover thicknesses, such as 20 mm (0.8). A good base may be provided by the present study for future development of concrete structure service-life assessment and realistic durability design.