EAGER: Corrosion Reduction in Reinforcing Steel of Concrete Structures through Grain Size Alteration

混凝土结构中的钢筋锈蚀是混凝土结构劣化的关键参数之一。据推测，减小钢材中的晶粒度可以显著减少钢筋的锈蚀。将进行分析和实验研究，以确定颗粒大小和腐蚀程度之间的关系。在这个初步构想的探索性研究奖助金项目中，实验将包括将钢筋放入模拟的混凝土环境中。钢中的晶粒度将通过热循环来改变，以确定晶粒度对腐蚀和机械性能的影响。钢筋将受到氯离子污染的混凝土孔洞溶液的影响，并将使用不同的微观和光谱分析来评估锈蚀钢筋的腐蚀程度。通过标准试验获得不同晶粒度的钢的力学性能。在这个探索性项目中，将对改变晶粒度的成本进行分析，以确定该工艺的可行性。将使用电子背散射衍射技术来获得定量的显微结构图，以确定钢样的结晶性质。该技术揭示了样品的晶粒度、晶界特征、晶向、织构和相同性。分析模型中的显微组织图可用于预测不同晶粒度的钢的点蚀行为。使用扫描电化学显微镜、X射线光电子能谱和光学轮廓仪可以获得钢的物理和化学成分。分析模型将包括点蚀增长作为一个变量。将根据减少腐蚀所需的晶粒度进行生命周期成本分析。为此目的，将使用衡量建筑物寿命周期成本的成本分析标准中的程序。这一探索性项目的最终结果将是了解钢筋在混凝土环境中暴露的晶粒度与腐蚀的关系。

Corrosion of reinforcing steel in concrete structures is one of the critical parameters in deterioration of concrete structures. It is hypothesized that reduction in grain size in steel can significantly reduce corrosion in reinforcing bars. Analytical and experimental studies will be pursued to correlate between grain size and level of corrosion. The experiments in this EArly-concept Grant for Exploratory Research (EAGER) project will include putting the reinforcing steel in the simulated concrete environment. The grain size in steel will be altered using thermal cycles to determine effects of grain size on corrosion and mechanical properties. The reinforcing steel will be subjected to chloride contaminated concrete pore solution and the level of corrosion on the corroded steel bars will be assessed using different microscopic and spectroscopic analyses. Mechanical properties of the steel with different grain sizes will be obtained with standard tests. Cost analysis of the alteration of grain size will be pursued in this exploratory project to determine viability of the process.Electron backscatter diffraction technique to obtain quantitative microstructural map will be used for crystallographic nature of the steel specimens. This technique reveals grain size, grain boundary character, grain orientation, texture, and phase identity of the specimens. The microstructural map in an analytical model will allow predicting the pitting corrosion behavior of steel with different grain sizes. Physical and chemical composition of the steel will be obtained using scanning electrochemical microscopy, X-ray photoelectron spectroscopy, and optical profiler. The analytical model will include pitting growth as a variable. Life cycle cost analysis will be pursued as related to grain size necessary to reduce corrosion. A procedure that is in a standard for cost analysis for measuring life cycle costs in buildings will be used for this purpose. The final results of this exploratory project will be to understand corrosion as related to grain size of steel exposed to environment of concrete.