氯離子侵蝕是研究鋼筋混凝土耐久性重要指標，大量實驗檢測及其研究理論 依據大都以Fick 第二滲透定律(Fick’s diffusion second law)為基礎。儘管Fick 第二 滲透定律可以用來預測使用壽命，但是至今仍沒有建立完整的理論體系。就Fick 滲透定律而言是目前研究大多限定於一維單向滲透條件下之實驗規劃及理論修 訂，進而計算氯離子滲透係數，進行實驗結果與理論修訂之合理性印證。在考量 實驗規劃之限制性，本研究將引入前進模式(advancing model)進行雙向滲透於有 限厚度條件下之Fick 理論修訂。

Nowadays, reinforced concrete is widely used as the material on building structures. It has perfect combination with tenacity of reinforcement and compression of concrete. The corrosion causes volume of reinforcement expanding, and the main factor which affects durability of concrete structures is the rusty reinforcement. Concrete has good compression but it doesn’t have well tenacity. Therefore, concrete’s tension crack, and cause the concrete’s surface peeling. The diffusion of chloride ion is the main reason cause reinforcement corrosion. Therefore, the diffusion degree of chloride ions is used as the standard to evaluate reinforcement concrete structure’s life. The diffusion of chloride ion is the important standard for researching reinforcement concrete structure’s life. And many experiments and study theories are based on Fick’s diffusion second law. Although it could apply to predicate reinforcement concrete structure’s life, it still not established the complete theoretical system. The experiment and theory revised of Fick’s diffusion law is limited in the condition of one-dimensional so far, and calculate the diffusion coefficient of chloride ion. In the limit of experimental analyses for modifications of Fick’s diffusion law, this study will apply two-dimensional diffusion advancing model of finite thickness.,