Understanding the influence of interface transition zone (ITZ) on chloride migration characteristics in concrete under coupled stray current and high hydraulic pressure is essential to solve the durability problem of ultra-deep buried infrastructures (40 m-100 m). Herein, an advanced test system is developed and the chloride migration characteristics of deeply buried concrete is comprehensively investigated. Specimens were casted with the same aggregate volume content but different aggregate size distribution. The ITZ between aggregate and cement matrix was measured from BSE (back scattered electron imaging) images, and the ITZ thickness was measured by Vickers hardness. The silver nitrate spray was used to determine the chloride migration front, and the effective diffusion coefficient was calculated. The results showed the concentric expansion and overflow method based on BSE images were effective ways to determine ITZ porosity distribution. The significant increase of ITZ thickness and porosity on concrete reaction surface under stray current environment was observed and defined as “stray current induced ITZ effect”, which was considered to be the fundamental reason for the distinct differences in chloride migration depth and effective diffusion coefficient of specimens with different aggregate gradations.

了解杂散电流和高水压耦合作用下界面过渡区（ITZ）对混凝土中氯离子迁移特性的影响对于解决超深埋基础设施（40 m-100 m）的耐久性问题至关重要。本文开发了先进的测试系统，全面研究了深埋混凝土的氯离子迁移特性。所铸造的样品具有相同的骨料体积含量但不同的骨料尺寸分布。通过 BSE（背散射电子成像）图像测量集料和水泥基体之间的 ITZ，并通过维氏硬度测量 ITZ 厚度。使用硝酸银喷雾确定氯离子迁移前沿，并计算有效扩散系数。结果表明，基于BSE图像的同心扩张和溢流法是确定ITZ孔隙度分布的有效方法。观察到杂散电流环境下混凝土反应面ITZ厚度和孔隙率显着增加，并将其定义为“杂散电流诱导ITZ效应”，这被认为是氯离子迁移深度和有效扩散系数存在明显差异的根本原因。具有不同骨料级配的样本。