| 摘要(英) |
This main topic in this study is to discuss the coupled deterioration processes of concrete structures subjected to external sulfate attack. In addition to the diffusion process of sulfates in concrete microstructure, the second order reaction between sulfates and calcium aluminates in cement is also considered. The product of this second order reaction is ettringite, which has the expansive nature and will cause the expansion of concrete, thus increases the diffusivity of sulfates in concrete and the rate of expansion of the structure.
To simulate the coupled deterioration processes, the diffusion-reaction approach considered in this study is solved to find out the spatial and temporal distribution trend of sulfates and aluminates in concrete using the finite element software ABAQUS, the numerical computation of expansion is then performed adopting the theoretical model proposed in the reference (Tixier 2000).
After the numerical simulation and the parametric study, the following conclusions are obtained, (1) The concentration distribution solved in this coupled diffusion-reaction approach is mainly controlled by the diffusivity of sulfates rather than the rate constant of reaction. (2) The size of the concrete cross-section will significantly affect the total time cost in the coupled deterioration processes. (3) The maximum amount of expansion is controlled by the initial concentration of calcium aluminates, but reduced by the material properties of concrete such as capillary porosity and tensile strength etc.
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| 參考文獻 |
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