Simulation for Corrosion Cracking of Cover Concrete in Reinforced Concrete Structures

Abstract

This study was conducted to propose a simulation model for corrosion cracking of cover concrete in reinforced concrete structures located on land and subjected to airborne chloride. Chloride penetration has been known to have great influences on the design corroded mass due to the fact that it changes the corrosion initiating time and corrosion rate. Accordingly, a chloride penetration model was proposed for reinforced concrete structures located on land. This model was verified with the drawn core of concrete specimens taken from structures that were free from the rain washout effect. In this study, the corrosion rate of reinforcing steel was also proposed by considering the change in degree of saturation in concrete due to environmental conditions. With the changes in the degree of saturation, the effective corrosion rate is changed according to three controlling factors: the conductivity of the concrete, the chloride concentration and the supply flux of oxygen. Therefore, the design corroded mass is the integration of the effective corrosion rate from the corrosion initiating time to the design time. Moreover, a numerical formula for limit corroded mass, which causes cracks in cover concrete, was developed and proposed. The accuracy of the formula was approximately 25% as compared to the experimental results of previous studies. Thus, the cracking time is the time when the design corroded mass is greater than the limit corroded mass. Additionally, the simulations at the time of cracking in cover concrete were compared with three actual reinforced concrete bridges subjected to airborne chloride.

Durability Design Method Considering Reinforcement Corrosion due to Water Penetration

“…A limit of the corrosion amount at which corrosion cracking occurs (d crack ), with a value ranging from 10 to 100 mg/cm 2 was proposed (JSCE 2007b;Piyamahant et al 2013;Takewaka and Matsumoto 1983), and it was reported that a value of 10 mg/cm 2 corresponded to a conservative estimation concerning the time of occurrence of corrosion cracking (JSCE 2007b). In addition, d crack was reported to increase with increase in the concrete cover thickness.…”