Effect of deicing chemicals on the strength and deterioration of concrete.

摘要

An experimental program was undertaken at the University of Manitoba to evaluate the effects of several deicing chemicals currently used or considered for use by the industry in the presence of freeze-thaw cycles. The deicing chemicals selected for this investigation were sodium chloride, corrosion-inhibited calcium chloride, corrosion-inhibited magnesium chloride (ICE-BAN 200M), and potassium acetate. In order to carry out the objectives of this investigation, 118 concrete cylinders, 10 concrete prisms, and 12 reinforced concrete beams were fabricated in order to determine the changes in scaling resistance, and physical and mechanical properties of the concrete elements. The samples were exposed to the deicing chemicals and placed in an environmental chamber where they were subjected to freeze-thaw cycles ranging from -25°C +/-3°C to 23°C +/-2°C over a period of 6 months. Concrete deterioration during the freeze-thaw cycles was evaluated on the basis of mass loss or gain and degree of scaling. The changes in the mechanical properties of concrete were determined in terms of loss of tensile, compressive and flexural strength, and changes in the static modulus of elasticity. The results of the samples were compared to control samples that were not exposed to freeze-thaw cycles or deicing chemicals. The results of the compression test were also compared to samples stored in deicing solutions in the absence of freeze-thaw cycles. Finally a Water Soluble Chlorides Test was carried out by the National Testing Laboratories to evaluate the penetration of corrosion-inducing chlorides with depth.; The results of this study have many important implications in the effort to obtain a greater understanding of the impact that alternative deicing chemicals may have on the long-term durability of concrete materials. The results of this investigation suggest that the proposed deicing chemicals react with concrete through various deterioration mechanisms to reduce the strength and durability of concrete structures. This research will assist transportation industries to better select effective yet benign deicing chemicals. As a result, the long-term durability and life of transportation infrastructure and assets will be maintained.