A mechanistic approach for predicting the service life & performance of steel reinforced concrete bridge becks

当今世界面临的一个重大问题是基础设施的老化。全世界保护和修复混凝土结构的费用是一个日益严重的大问题（每年的支出超过1 000亿美元）。这种衰退的一个主要组成部分是由于嵌入钢筋的腐蚀而导致的桥梁和公路的退化。这一问题促使开发了各种替代策略，以增加暴露在恶劣环境中的钢筋混凝土结构的使用寿命。在最知名的程序中，可以提到：化学腐蚀抑制剂，钢筋保护涂层，耐腐蚀钢（不锈钢，MMFX等），混凝土外露表面的防水膜或密封剂、阴极保护、高性能混凝土等。这些替代技术中的每一种都有不同的技术优点和使用成本。最佳设计/维修策略不仅需要估计前期成本，还需要将所有相关成本与结构寿命的潜在延长进行比较的方法。在考虑新开发的材料（如不锈钢、MMFX和FRP复合材料）时，这个问题最难回答，因为缺乏有关其现场性能的历史数据。在这种情况下，基于第一原理，机械方法已被证明是在以前未经测试的条件下进行可靠预测的非常强大的工具。拟议的研究的主要目标是开发可靠的使用寿命预测使用先进的理论和实验技术，包括同步加速器为基础的测试方法健全的机械模型。加拿大光源（国家同步加速器设施：http://www.lightsource.ca）在美国校园的存在提供了进行前所未有的高分辨率材料显微镜分析的机会。同步加速器光覆盖光谱的全部范围;允许比以往任何时候都更高的准确度和精度;并允许在一般环境条件下（水分，化学反应等）进行真实的时间探测。

One of the significant problems facing the world today is the decay of infrastructure. The cost of protecting and restoring concrete structures worldwide is a large and growing problem (more than $100 billion in annual expenditures). A major component of this decay is the degradation of bridges and highways due to corrosion of the embedded reinforcing steel. This problem has prompted the development of a variety of alternative strategies for increasing the service life of reinforced concrete structures exposed to harsh environments. Among the most well known procedures, one can mention: chemical corrosion inhibitors, protective coatings on steel reinforcement, corrosion-resistant steels (stainless steels, MMFX, etc.), waterproofing membranes or sealants applied to the exposed surface of the concrete, cathodic protection, high performance concrete etc. Each of these alternative technologies has different technical merits and costs associated with their use. An optimum design/repair strategy requires not only an estimate of upfront costs, but also the means to compare all associated costs against the potential extension to the life of the structure. This issue is hardest to answer when considering newly developed materials (such as stainless steels, MMFX, and FRP composites) because of a lack of historical data about their field performance. In such situations, based on first principles, mechanistic approaches have proven to be very powerful tools for making reliable predictions under previously untested conditions. The main objective of the proposed research is to develop sound mechanistic models for reliable service life predictions using advanced theories and experimental techniques, including synchrotron-based testing methods. The presence of the Canadian Light Source (the national synchrotron facility: http://www.lightsource.ca) on the U of S campus provides the opportunity to conduct unprecedented high resolution microscopic analyses of materials. Synchrotron Light covers the full range of the light spectrum; allows greater accuracy and precision than has ever before been possible; and allows matter to be probed in real time under general environmental conditions (moisture, chemical reactions, etc.)