Frost Deterioration in Concrete Due to Deicing Salt Exposure: Mechanism, Mitigation and Conceptual Surface Scaling Model.

Salt frost scaling;Cryogenic suction;Sorptivity;Ice growth;Civil and Environmental Engineering;Engineering;Civil Engineering

Liu, ZhichaoKoenders, Eddy A.b. ;

University of Michigan

关键词: Salt frost scaling;    Cryogenic suction;    Sorptivity;    Ice growth;    Civil and Environmental Engineering;    Engineering;    Civil Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/110430/lzc_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Michigan is located in a wet-freeze climate zone. During winter the deicing-salt application is needed to melt snow on highways. Freezing in the presence of a deicing salt solution is considered a severe concrete exposure condition. Prolonged exposure in pavement joints has been found to erode the concrete binder material (portland cement paste) when coupled with its low internal frost resistance (i.e. insufficient air and poorly drained joints). This creates a weak zone resulting in joint spalling from heavy wheel loading. Many highways have been found to suffer this type of distress within ten years requiring expensive joint repairs. This research investigates the material level mechanisms for frost deterioration under deicing salt exposure by the aid of systematic application of various experimental techniques, such as sub-freezing length change measurement, micro- and macro-characterization of scaling properties and nitrogen sorption test. A new conceptual model is provided for the surface deterioration that occurs within a thin surface layer when exposed to a deicing salt solution. The major stress producing mechanism is ice-growth within the capillary pores exacerbated by cryogenic suction of the liquid brine present on the surface, thus feeding further ice-growth and leading to high tensile stresses in the direction of least internal restraint and ;;popping” of thin mortar flakes. This process repeats itself for every freeze-thaw cycle. These findings pave the way for the proposal of sorptivity as a performance-based criterion to evaluate scaling resistance in concrete and its theoretical nature is enhanced by a refined model capable of capturing the effect of pore size characteristics (pore volume, its size distribution and connectivity). This further leads to the identification and application of effective mitigation techniques, including reconfiguration of paste pore system towards a more refined and discontinued structure and utilization of a hydrophobic pore liner in the silicate substrate of hydration products as surface treatment.