Studies of the Carbonation Service Life Prediction of Existing Reinforced Concrete Bridges

• Main Author: 郭峻輔
• Other Authors: Ran Huang
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/66709055285242002690

碩士 === 國立臺灣海洋大學 === 河海工程學系 === 97 === The carbonation problem due to the carbon dioxide in atmosphere penetrated into concrete through pore void is one of important factors of corrosion of existing reinforced concrete (RC) structures. Aside from material factor, both temperature and relative humidity (RH) are the principal environment factors which influence the carbonation problem of existing RC structures. When RH are larger or less than 70%, the carbonation zone in concrete can be divided into carbonated and noncarbonated zones or carbonated, partially carbonated and noncarbonated zones, respectively. The main aim of this article is to predict the carbonation life of existing RC bridges. The investigated methods are used to find the analytical solutions of one-dimensional linear (diffusivity D = constant) and nonlinear (D ≠ constant) diffusion and diffusion-chemical reaction equations associated with initial and boundary conditions, respectively. The carbonation life can be calculated from the analytical solutions through the Mathematica software. These theoretical models are applied to predicting the carbonation life of existing Dah-du and Dah-jin RC bridges in Taiwan. The results of present studies show that the one-dimensional nonlinear diffusion equation is suitable for bridges under RH＞70% condition whereas the one-dimensional linear diffusion-chemical reaction equation is suitable for bridges under RH≦70%. The studied results may be offered as a crucial reference for engineering decision making for repair, strengthening or demolition of existing RC bridges.