Time-varying relative displacement field on the surface of concrete cover caused by reinforcement corrosion based on DIC measurement

To investigate the cracking process of concrete cover due to corrosion of reinforcement for concrete specimens subjected to semi-immersed accelerated corrosion, digital image correlation (DIC) was applied to quantitatively and visually characterize the development of relative displacement on the viewed surface. The impacts of stirrups and concrete cover thickness on the evolution of relative displacement were interpreted. And a detailed analysis covered the initial cracking time, position and relative displacement distribution on the surface during the cracking procedure. The study indicates that the corrosion of stirrups is prior to longitudinal reinforcement as the longitudinal reinforcement is cathodic protected by stirrups. The full-scale monitoring on the relative displacement reveals that a thicker concrete cover can retard the initial cracking but will promote the propagation speed of corrosion cracks. The investigation on the initial cracking zone implies that the initial cracking has high probability to appear within a region and its width is approximately close to the concrete cover thickness.