摘要
回顾了混凝土氯离子扩散理论模型研究的基本进展,指出了混凝土氯离子扩散研究中存在的问题:材料非均质性、有限大体、多维扩散、可变扩散系数与可变边界条件、结构微缺陷对扩散的加速作用、氯离子结合能力及其非线性等.针对多个暴露面的有限大长方体的氯离子扩散,引进了氯离子扩散的劣化效应系数和时间依赖性常数,提出了线性氯离子结合能力及其非线性系数,采用幂函数和指数函数修正了时间边界函数,系统地解决了混凝土的氯离子扩散理论问题.经过严密的数学推导,在理论上得到了综合考虑氯离子结合能力、氯离子扩散系数的时间依赖性和结构微缺陷影响的混凝土氯离子扩散新方程.结果表明,混凝土氯离子扩散新方程的简化表达式与Fick第二扩散定律在形式上完全一致.
Diffusion of chloride ion in concrete is an inhomogeneous and time-dependent process. This paper aims at establishing a theoretical model to describe the inhomogeneous and time-dependent process of chloride ion diffusion in concrete. Firstly the state of the art in research on diffusion of chloride ion in concrete is reviewed and problems remained to be studied are pointed out, namely: material inhomogeneous, finite space, multiple dimension, variable diffusion coefficient and boundary condition, diffusion acceleration induced by structural defect, variable chloride bound capacity and the non-linearity, and so on. Aimed at resolving diffusion of chlorion in finite cuboid with multiple exposure surfaces, coefficients describing diffusion acceleration induced by structural defect and diffusion time-dependence are introduced. The linear and non-linear bound capacity are proposed, and power and exponential function are adopted to modify time boundary conditions. Lastly, a new diffusion equation is formulated based on mathematic derivation. Influential factors of chloride binding capacity, time-dependence of chlorion diffusion and micro-defects of concrete are taken into consideration. Simplified form of the proposed diffusion equation is similar to Fick's second law.
出处
《东南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2006年第S2期68-76,共9页
Journal of Southeast University：Natural Science Edition
基金
江苏省自然科学基金前期预研资助项目(BK2005216)
国家自然科学基金资助项目(50178044)
国家自然科学基金重点资助项目(59938170).
关键词
混凝土
氯离子扩散
模型
边界条件
结合能力
concrete
diffusion of chloride ions
model
boundary condition
chloride binding capacity
