A Study of Concrete Cracking Behavior Due to Non-uniform Corrosion of Reinforcing Bars

A recent study by Yuan and Ji (2009) has shown an experimental evidence of non-uniform corrosion and non-symmetric volume expansion of reinforcing bars in a reinforced concrete member. The concrete cracking behavior due to non-uniform corrosion could be different from that computed from the common assumption of uniform corrosion. This paper describes the results of a parametric investigation on concrete cracking behavior due to non-uniform corrosion of rebars, as affected by the major corrosion related factors such as concrete strength, cover thickness, corrosion patterns and the position of the rebar. To perform the parametric investigation, a mathematical model is established for quantitatively describing the non-uniform volume expansion of rebars. Then a finite element based approach is developed for tracking the propagation of concrete cracking as the corrosion level of the rebars evolves over time. The important conclusions include: (1) the size of the porous zone is the predominant factor which determines the time to initial cracking of concrete cover; (2) the time to penetrating cracking increases with the increase in concrete strength and cover thickness; (3) compared to uniform corrosion, non-uniform is conducive to cracking due to the concentration of expansive pressure; (4) the appearance of cracking on cover surface surrounding corner positioned rebars could be much earlier than the case for side positioned rebars in an identical concrete component.