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衰败。在世界范围内，保护和修复混凝土结构的成本是一个巨大且日益严重的问题（每年的支出超过1000亿美元）。这种腐蚀的一个主要组成部分是桥梁和高速公路的退化，因为嵌入的钢筋被腐蚀。这一问题促使了各种替代策略的发展，以增加暴露在恶劣环境下的钢筋混凝土结构的使用寿命。在最著名的程序中，人们可以提到：化学腐蚀剂，钢筋保护涂层，耐腐蚀钢（不锈钢，MMFX等），防水膜或密封胶应用于混凝土的暴露表面，阴极保护，高性能混凝土等。每一种替代技术都有不同的技术优点和使用成本。优化设计/维修策略不仅需要预估前期成本，还需要将所有相关成本与结构寿命的潜在延长进行比较。当考虑到新开发的材料（如不锈钢、MMFX和FRP复合材料）时，由于缺乏有关其现场性能的历史数据，这个问题最难回答。在这种情况下，基于第一原理，机械方法已被证明是非常强大的工具，可以在以前未经测试的条件下做出可靠的预测。提出的研究的主要目标是利用先进的理论和实验技术，包括基于同步加速器的测试方法，为可靠的使用寿命预测开发健全的机制模型。在美国大学校园的加拿大光源（国家同步加速器设施：http://www.lightsource.ca）的存在提供了对材料进行前所未有的高分辨率微观分析的机会。同步加速器光覆盖了整个光谱；允许更高的准确性和精度比以往任何时候都是可能的；并允许在一般环境条件下（湿度，化学反应等）对物质进行实时探测。

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.)