Corrosion characteristics and critical corrosion depth model of reinforcement at concrete cover cracking in an electrochemical accelerated corrosion environment

The relationship between corrosion characteristics and electrochemical indicators detected by the half-cell potential method is unclear. In this study, the corrosion characteristics of steel reinforcement exposed to an accelerated corrosive environment were investigated. Firstly, three series of concrete specimens were prepared for the electrochemically accelerated corrosion test. The corrosion potential, galvanic current, and concrete resistance were obtained via an Anode-Ladder-System. The relationships between Cl - penetration depth, Cl - content, and electromigration time were discussed. Secondly, the corrosion ratios of rebar under different electromigration times were evaluated. The relationships between corrosion ratio of a rebar, Cl - content, and corrosion potential were analyzed. The critical corrosion depth of a rebar at concrete cover cracking was determined. Finally, a theoretical model for the critical corrosion depth of a rebar was established via elastic-plastic mechanics and fracture mechanics. The critical corrosion depths for different concrete cover thicknesses and rebar diameters were predicted. The results indicated that the relationship between corrosion ratio of rebar, Cl - content, and corrosion potential was exponential. The relationship between Cl - penetration depths, Cl - content, and corrosion ratio of rebar was logarithmic. As the concrete cover thickness increased and the rebar diameter decreased, the critical corrosion depth of rebar increased as a power function. When the concrete cover thickness was 10 mm and the rebar diameter was 10 mm, the critical corrosion depth was 13.5μm. The theoretical model can be utilized to predict critical corrosion depth under low concrete strength (less than C40) and small concrete cover thickness (less than three times rebar diameter). This study provides preliminary theoretical support for corrosion characteristics of reinforcement exposed to a corrosive environment.