Impacts of Potassium Acetate and Sodium-Chloride Deicers on Concrete

The use of deicers in cold regions has raised many concerns regarding their negative impacts on the durability of concrete infrastructure. Numerous studies have been conducted in the laboratory settings with respect to the chemical and physical deterioration of concrete as a function of deicer type. However, little research has been done with concrete structures in the field, especially concrete bridge decks whose durability is also affected by temperature cycling and mechanical loadings. In this study, the effects of sodium chloride (NaCl) and potassium acetate (KAc) deicers were investigated using concrete samples obtained from the field bridge deck coring and those prepared in the laboratory. The relevant tests of both the field-cored and laboratory-fabricated concrete samples revealed that the two deicers (NaCl and KAc) imposed negative impact on the durability of the concrete materials. To compare the practical implications of these two deicers on concrete, their ice-melting capacity was tested. In addition, the mass loss, mechanical properties, including splitting tensile strength, compressive strength, and microhardness were tested to evaluate the deterioration of concrete samples after exposure to KAc and NaCl respectively. Relative to NaCl, field exposure to KAc caused more damage to concrete decks, partially due to the use of reactive aggregate. To further understand the deterioration effect of NaCl and KAc deicers on concrete materials, designed tests were carried out with laboratory-fabricated concrete samples. In both cases, the compressive and splitting tensile strengths of such samples decreased considerably after 3, 7, and 15 freezing/thawing (F/T) and wetting/drying (W/D) cycles. In addition to Ca leaching, needle-shaped and rod-shaped precipitates formed in concrete samples after F/T and W/D cycles in NaCl and KAc, respectively. The formation of these precipitates could be attributed to the chemical reactions between the cement paste and the deicers, and such crystallization process may lead to volume expansion of the pores in concrete. (C) 2016 American Society of Civil Engineers.