Analytical Solutions for Corrosion‐Induced Cohesive Concrete Cracking

Abstract

The paper presents a new analytical model to study the evolution of radial cracking around a corroding steel reinforcement bar embedded in concrete. The concrete cover for the corroding rebar is modelled as a thick-walled cylinder subject to axisymmetrical displacement constraint at the internal boundary generated by expansive corrosion products. A bilinear softening curve reflecting realistic concrete property, together with the crack band theory for concrete fracture, is applied to model the residual tensile stress in the cracked concrete. A governing equation for directly solving the crack width in cover concrete is established for the proposed analytical model. Closed-form solutions for crack width are then obtained at various stages during the evolution of cracking in cover concrete. The propagation of crack front with corrosion progress is studied, and the time to cracking on concrete cover surface is predicted. Mechanical parameters of the model including residual tensile strength, reduced tensile stiffness, and radial pressure at the bond interface are investigated during the evolution of cover concrete cracking. Finally, the analytical predictions are examined by comparing with the published experimental data, and mechanical parameters are analysed with the progress of reinforcement corrosion and through the concrete cover.

Analytical Model for Residual Bond Strength of Corroded Reinforcement in Concrete Structures

“…However, as pitting corrosion progresses, it appears as uniform corrosion in the later stage, as demonstrated in the long-term natural corrosion experimental studies by Zhang et al (2010). The assumption for uniform expansive pressure at the bond interface is reasonable, as shown in many studies such as Balafas andBurgoyne (2011), Bhargava et al (2008), Chen and Xiao (2012), Chernin et al (2010) and Zhong et al (2010).…”

Stochastic modelling and lifecycle performance assessment of bond strength of corroded reinforcement in concrete

“…The concrete cracking process due to reinforcement corrosion has been investigated analytically by adopting the anisotropy of cracked concrete and thick walled cylinder model previously utilized by Chen and Xiao (2012) together with the concept of equivalent crack as utilized by Chen and Alani (2013). The schematic representation of thick walled cylinder model used in this paper is shown in Fig.…”

“…in which l o cr and l o u are the aforementioned material constants for pre-critical stage and postcritical stage cracking of the concrete cover. By considering free surface condition at the cover surface and ignoring the Poisson's effect associated with the hoop strain of the completely cracked concrete, the normalized crack width on the concrete cover surface W cx can be obtained from Chen and Xiao (2012), expressed here as…”

“…In cohesive crack model the process of concrete cracking continues until they reach their Fig. 4 Bond mechanisms for deformed reinforcing rebar ultimate cohesive value W u Xiao 2012, Chen and. Therefore, the corrosion level X p u at which the equivalent crack in the concrete cover reaches its ultimate cohesive value can be obtained from Eq.…”

“…in which μ x is the coefficient of the friction between the corroded rebar and cracked concrete defined as 0.37−0.26(x−x c ) and P corrx is the corrosion pressure or the radial pressure acting at the bond interface due to the accumulation of the corrosion product at the rebar surface. The corrosion pressure acting at bond interface can be evaluated from Chen and Xiao (2012)  …”