• Estimating the Application Rate of Liquid Chloride Products Based on Residual Salt Concentration on Pavement

      Fay, Laura; Akin, Michelle; Muthumani, Anburaj (Center for Environmentally Sustainable Transportation in Cold Climates, 2018-03-21)
      This technical report summarizes the results of laboratory testing on asphalt and concrete pavement. A known quantity of salt brine was applied as an anti-icer, followed by snow application, traffic simulation, and mechanical snow removal via simulated plowing. Using a sample from this plowed snow, researchers measured the chloride concentration to determine the amount of salt brine (as chloride) that remained on the pavement surface. Under the investigated scenarios, the asphalt samples showed higher concentrations of chloride in the plowed-off snow, and therefore lower concentrations of chlorides remaining on the pavement surface. In comparison, the concrete samples had much lower chloride concentrations in the plowed-off snow, and much higher chloride concentrations remaining on the pavement surface. An interesting pattern revealed by the testing was the variation in the percentage of residual chloride on the pavement surface with changes in temperature. When pavement type was not considered, more residual chloride was present at warmer temperatures and less residual chloride was present at colder temperatures. This observation warrants additional testing to determine if the pattern is in fact a statistically valid trend. The findings from the study will help winter maintenance agencies reduce salt usage while meeting the defined Level of Service. In addition, findings will contribute to environmentally sustainable policies and reduce the level of salt usage (from snow- and ice-control products) introduced into the environment.
    • Investigation of Alternative Deicers for Snow and Ice Control

      Fay, Laura; Akin, Michelle (Center for Environmentally Sustainable Transportation in Cold Climates, 2018-03-15)
      This technical report presents the findings of the laboratory analysis of potassium succinate (KSu) as a roadway deicer. Laboratory analysis included modified SHRP ice-melting testing, a differential scanning calorimetry (DSC) thermogram, and friction measurements to quantify performance. The overall results indicate that the performance of KSu is similar to that of NaCl at improving friction on roadways during snow and ice conditions. The results of DSC suggest that KSu can be applied as a roadway deicer at -5°C (23°F) and above. However, KSu does not function as a deicer at colder temperatures where salt brine will work (the generally agreed upon lowest working temperature for salt brine is 15°F [-9.5°C]). The results of the laboratory testing show that KSu functions as a roadway deicer with slightly lower ice-melting rates than salt brine. The ice-melting rates, DSC, and friction performance testing of KSu show that the product performs as a deicer at warmer temperatures than salt brine, with slightly less ice-melting capacity and similar friction performance. Based on these and previous results showing lack of corrosion in metals, equipment, and pavements from use of KSu and similar BOD of KSu to potassium acetates, KSu appears to be a viable option as a roadway deicer at temperatures at or above -5°C (23°F). Use of KSu as a roadway deicer may be focused in areas where there are concerns about impacts to infrastructure, equipment, or pavements, such as on bridges, elevated roadways, in parking garages, or on newer concrete pavements. Potential concerns with the use of KSu as a roadway deicer are its price, lack of full-scale manufacturing of KSu at this time, and the BOD exerted by the product. Additional testing to fully quantify the environmental impacts of KSu on soil, water, flora, and fauna is recommended. If water quality and BOD are of concern, application of this product is not recommended in large quantities and during times of low water flow.