基于蒙特卡洛法，利用Python与Abaqus接口进行二次开发，生成区分天然粗骨料，新、旧界面过渡区（interfacial transition zone, ITZ）和新、旧砂浆的再生混凝土（recycled aggregate concrete, RAC）二维细观五相模型。提出改进的干湿循环下水分-氯离子耦合模型，并将该模型的计算结果与物理试验进行对比验证，结果吻合较好。将该模型应用于分析干湿循环周期、ITZ渗透率、水胶比和天然骨料体积分数对氯离子传输性能的影响规律。结果表明，在干湿循环次数增加的情况下，RAC中氯离子的扩散深度和浓度也会随之增加。当ITZ扩散系数与新砂浆扩散系数的比值增大时，氯离子的扩散区域中氯离子浓度增加明显，尤其是在扩散区的前端位置氯离子浓度增加最为显著。此外，不同水灰比的RAC材料与氯离子的传输能力之间存在正相关关系，高水灰比范围内氯离子传输性能变化较小。最后，再生骨料体积分数对RAC的抗氯离子渗透性能产生显著影响，这说明ITZ和新旧砂浆对氯离子的传输具有重要影响。

Based on Monte Carlo method, Python and Abaqus interface were used for secondary development, and an interfacial transition zone was generated to distinguish between natural coarse aggregates and new and old interfacial transition zone(ITZ) and recycled aggregate concrete (RAC) 2D meso-five phase model of new and old mortar. An improved moisture-chloride ion coupling model under dry-wet cycles was proposed, and the computational results of this model were compared and validated against physical experiments, with good agreement. This model was then applied to analyze the effects of dry-wet cycle periods, ITZ permeability, water-cement ratio, and natural aggregate volume fraction on chloride ion transport properties. The numerical results show that as the number of dry-wet cycles increases, the diffusion depth and concentration of chloride ions in RAC also increases. When the ratio of ITZ diffusion coefficient to the new mortar diffusion coefficient increases, the chloride ion concentration in the diffusion region increases significantly, especially at the front end of the diffusion zone. In addition, there is a positive correlation between RAC materials with different water-cement ratios and chloride ion transport capacity, with little variation in chloride ion transport performance within the high water-cement ratio range. Finally, the volume fraction of recycled aggregates has a significant impact on the chloride ion permeability of RAC, indicating that the ITZ and new and old mortar have an important influence on the transport of chloride ions.