Predicting carbonation in early-aged cracked concrete

Carbonation in cracked concrete is considered as one of major deteriorations accelerating steel corrosion in reinforced concrete structures. For durable concrete structures, it is necessary to control crack in concrete through crack resistance evaluation for early-aged concrete structures, but often unavoidable cracks in early-aged concrete may occur. These cracks become a main path for CO2 penetration inside concrete so that the carbonation is accelerated in cracked concrete.In this study, an analytical technique for carbonation prediction in early-aged cracked concrete was developed for considering both CO2 diffusion of pore water in sound concrete and in cracked concrete. Then, characteristics of diffusivity on the carbonation in early-aged concrete are studied through finite element analysis implemented with the so-called multi-component hydration heat model and micro-pore structure formation model. The carbonation behaviour in sound concrete and cracked concrete are also simulated by using the derived diffusivity with consideration of reaction with dissolved CO2. Finally, numerical results obtained for cracked concrete made with 3 different W / C ratios (45%, 55%, and 65%) with different crack widths were compared with experimental results.