Time Evolution of CO2 Diffusivity of Carbonated Concrete

Carbonation of cementitious materials is one of main causes of reinforcement corrosion and CO2 diffusivity influenced by microstructural characteristics of the cementitious materials is a decisive parameter for the carbonation rate. This study focused on establishing a multifactor functional model to calculate the CO2 diffusivity of carbonated cementitious materials. Because CO2 gas flows through carbonated zone, it is necessary to estimate CO2 diffusivity of carbonated concrete. Many factors on the CO2 diffusivity, such as the diffusivity in vapor, tortuosity, microstructural characteristics of cement paste, contribution of aggregate, and reduction of porosity due to carbonation, were considered. Apparent and effective CO2 diffusivity were calculated according to the absence or presence of moisture in the pore system of concrete, and the results were compared with previous research.