Microscopic Study of Ice Formation and Propagation in Concrete

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Despite the significant progress research has made in mitigating the damage to portland cement concrete from ice formation and propagation, frost action continues to cause serious damage to structures exposed to the elements. P.I.s plan to use a new microscopic technique using `directional cooling` to undertake a comprehensive research program on ice formation and propagation in concrete and its components. This study will characterize the ice morphology and velocity in various concrete pore solutions, it will establish local concentrations of super-cooled water and it will determine the dynamics of ice propagation in concrete as a function of different amounts of air-entrained voids and deicers. The interaction of ice crystals with the concrete microstructure will be characterized at high magnifications using a new-generation field emission low-temperature scanning microscope, which allows the study of ice formation in small voids. The relationship between the ice formation in concrete and the development of microcracks will be established using a recently developed acoustic emission set-up. The test results will create a link between microstructure and microcracking as affected by cooling rate, presence of deicers, and amount of air entrainment in the matrix. The results of this integrated research program will help the development of the next generation of high-performance concretes to be used in the repair of the aging reinforced concrete infrastructure exposed to cold climate.