Investigation of Anti-Icing Chemicals and Their Interactions with Pavement Concretes

摘要

The interactions of concrete specimens (both plain and with fly ash addition) with six different deicers was investigated by exposing them to solutions of sodium chloride (NaCl), magnesium chloride (MgCl2), calcium chloride (CaCl2), and the combinations of: sodium chloride with magnesium chloride (NaCl + MgCl2), sodium chloride with calcium chloride (NaCl + CaCl2), sodium chloride with agricultural by product – Ice Ban® (NaCl + Ice Ban®). In addition, control group of specimens was exposed to the deionized water. The exposures consisted of wet/dry (W/D) and freeze/thaw (F/T) cycles as well as a continuous storage in lime water at 23°C.The effects of various exposure conditions were evaluated based on the changes in the following: relative dynamic modulus of elasticity (RDME), ultrasonic pulse velocity (UPV), mass of specimens, length of specimens, mass of scaled material and compressive strength. In addition, absorption and chloride penetration measurements were performed for specimens exposed to various deicers at room temperature of 23°C. Finally, the qualitative visual evaluation of the appearance of the samples was also performed along with documentation of microstructural changes using the scanning electron microscopy (SEM).Among the deicer/anti-icers tested, calcium chloride and magnesium chloride solutions caused comparatively higher degree of deterioration than other solutions. Although the ultimate extent of visual degradation of the specimens exposed to both of these deicers was very comparable, the onset of the degradation process in specimens exposed to magnesium chloride was significantly delayed when compared to the onset of deterioration of specimens exposed to calcium chloride.The best performance (least amount of damage) was observed for specimens exposed to sodium chloride solutions followed by the specimens exposed to the combination of sodium chloride with magnesium chloride and sodium chloride with calcium chloride.The test results indicate that F/T exposure conditions are much more severe than W/D regimes, even though the concentrations of deicers/anti-icers used for F/T cycles were about 50% lower than those used for W/D cycles. Moreover, the addition of fly ash has a positive influence on performance of the concrete regardless of the type of the exposure regime.