纵贯海洋各腐蚀区带结构混凝土损伤演化与耐久性评估研究

Reinforced concrete of Cross-sea bridge and wharf services throughout marine different corrosion zones, its chloride ion tranportation and reinforced bar corrosion is not only on the plane and along the height direction. In this project, the main envrionment factors in each marine corrosion zone is analysis.And the loaded reinforced concrete specimens, construction members and structural models are exposed to throughout marine different corrosion zones, or to each corrosion zone and laboratory simulation environment. The microelectrode and durablity monitoring sensors are developed and used in durablity experiment and structure monitoring. Then the corrosion mechanism,damage evoluation of microstucture, humidity field of loaded reinforced concrete serviced in thoughout marine different zones is studied based on multi-scale theory, monitoring and modern testing instrument. The quantitative relationship between water/chloride ion trasmission coefficient, damage coefficient, steel corrosion current and microstructure, humidity field of reinforced concrete is estabilished. The 3D chloride ion transportion and reinforced bar corrosion modeling of concrete struture are proposed. And then the service life prediciton modeing of reinforced concrete serviced in thoughout marine different zones is established considering the similarity relation of environment-service life-structure model and compounding action of loading and marine corrosion environment. Then the durability database is established including long-term durablity monitoring datas of marine structure, ocean structure survey and marine environment datas. Based on reliability theory and durability database, the durability evaluation system of concrete structure serviced in marine environment is established.

纵贯海洋各腐蚀区带（海泥、水下、潮汐、浪溅和大气区）服役的跨海大桥、码头钢筋混凝土中的离子传输与钢筋锈蚀不仅在平面进行且在纵向发展。本项目提炼海洋各腐蚀区带主要环境影响因素，针对加载/非加载钢筋混凝土试件、构件和结构模型开展纵贯海洋各腐蚀区带，及分区带实海暴露和室内模拟试验。基于多尺度理论，结合自主研发与引进的微电极探针和耐久性传感器，利用纳米压痕、CT等先进测试手段，揭示纵贯海洋各腐蚀区带受荷钢筋混凝土的腐蚀机理及微结构损伤演化规律。动态监测混凝土中水分迁移并分析其湿度场。提出水分/氯离子传输系数、损伤系数、钢筋腐蚀电流等耐久性关键参数与混凝土微结构、湿度场的定量关系，建立混凝土中氯离子传输与钢筋锈蚀三维模型。通过环境-时间-结构相似关系的引入，考虑荷载-海洋环境耦合，建立纵贯海洋各腐蚀区带混凝土结构寿命预测模型。基于可靠度理论和耐久性数据库，建立海洋环境混凝土结构耐久性评估体系。

氯离子与硫酸根离子在混凝土中传输并诱导钢筋锈蚀和混凝土损伤是海洋钢筋混凝土腐蚀破坏的主要因素，离子传输与钢筋锈蚀不仅在平面进行而且在纵向发展，且受到混凝土材料、钢筋类型、环境湿度、裂缝的影响。本项目基于分析动力学模拟研究水作用下混凝土CSH凝胶的劣化，以及非饱和状态下的传输性能；采用电化学测试、XPS与AFM联合分析方法，揭示钢筋钝化膜这个纳观结构的形成与脱钝行为。采用实海与盐渍土暴露试验，研究海洋不同腐蚀区域，以及纵贯海洋、盐渍土各腐蚀区带混凝土中的氯离子、硫酸根离子传输与结合行为，系统分析其腐蚀产物性能及类型，揭示上述环境下混凝土最易腐蚀破坏区域。预制不同尺度横向和纵向裂缝混凝土研究其钢筋锈蚀行为。采用丝束电极技术分析裂缝对混凝土微区钢筋锈蚀电流/电位的定量影响规律，获得不同尺度、不同类型裂缝对混凝土中钢筋锈蚀定量影响规律。开发带钢筋圆环砂浆试件，测试其恒电位加速过程中的应变，获得不同腐蚀离子、不同砂浆类型对混凝土中钢筋锈胀应力的定量影响规律；利用数字图像技术动态追踪混凝土中钢筋锈蚀所诱导混凝土表面和侧面的应变场，并将其测试结果与电阻式应变片测试结果进行对照。利用X-CT和DIC技术分析混凝土内部任意平面应变场。基于上述测试方法，系统推导混凝土中钢筋锈蚀应力场演变。采用不同掺量粉煤灰、矿粉、硅灰以及复掺，超细钢纤维掺量为0-2%制备工作性良好，强度超过100MPa，体积稳定性良好的超高强水泥基材料；利用氧化石墨烯制备层层自组装高防腐涂层，利用碳纤维开发高性能导电水泥基材料并对腐蚀钢筋混凝土进行电化学除盐研究，综合提升海洋钢筋混凝土耐久性能。开发钢筋锈蚀监测和pH微电极，建立跨海桥梁混凝土结构耐久性监测系统，开发考虑混凝土材料、干湿循环及温湿度影响的混凝土中氯离子传输数值模拟系统，构建海洋环境混凝土结构耐久性评估体系。