Modeling the effects of fatigue damage on concrete carbonation

Abstract

This paper presents the theoretical modeling of carbonation in fatigue-damaged concrete. First, a residual strain-based effective carbon dioxide diffusion coefficient in fatigue-damaged concrete was proposed. Based on that, the general carbonation equations were established for concrete with uniform compressive, gradient compressive and gradient tensile damage patterns. Then a numerical program was written to solve the established partial differential carbonation equations. Subsequently, the numerical carbonation model was validated by comparing the predicted carbonation depths with experimental results. Finally, parametric studies were conducted on carbonation in commonly used concretes with various fatigue damage patterns, which separated the effects of residual strains and residual curvatures. The parametric studies showed that fatigue damage did not alter the widely accepted proportional relationships between carbonation depths and square roots of exposure durations. Moreover, the effects of exposure conditions on carbonation of concrete were far more influenced by residual strains than by residual curvatures.