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

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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.