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Abstract

The carbonation process of concrete is principally a diffusion phenomenon. The penetration rate of carbon dioxide depends mainly on the concrete quality and the exposure condition. Based on both Fick’s first and second laws of linear diffusion equations, the threedimensional equation of conservation of mass is expressed. This equation can be reduced to two- and one- dimensional equations of conservation of mass which can predict the carbonation depth beneath corners and the general surface of concrete structures, respectively. The objectives of this investigation are to measure the depth of carbonation from the free surface of a concrete member and to predict the carbonation depth using a statistical method. The result of the present study indicates that the maximum carbonation depth of concrete at corners is larger than 2 times that of the general surface under the conditions of homogeneous, isotropic and uncracked concrete subjected to static load. The carbonation depths of ten existing reinforced concrete (RC) bridges in Taiwan were predicted by the statistical method. The predicted results can be offered as a reference basis of repair, reinforcement or demolition for the existing concrete structures.

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