Bell, Matthew

The objective of this project was to develop materials to aid winter maintenance practitioners in making informed decisions on the use of road salts, specifically sodium chloride. To accomplish this, a detailed literature review was conducted, followed by a laboratory investigation that monitored ice formation and precipitation of salt at various concentrations and temperatures. Using the information collected through the previous tasks, a one-page fact sheet and educational video were developed to aid winter maintenance practitioners in how to use and apply information shown in salt phase diagrams. Results from the lab testing produced great images and video of ice and salt crystal formation in solution. Limited ice crystal data was collected and analyzed. Detailed ice crystal formation results could provide significant information to advance this topic. Images of ice crystals with bubbles, potentially filled with salt brine, indicate that the solid phase of ice crystals and salt crystals is not pure, implying that many phases can co-exist. This reinforces the concept that ice formed in the presence of salt brine is weaker than ice formed only in the presence of pure water. When measuring pavement friction following the application of salt brine at various concentrations, the results varied between pavement type, salt concentration, and friction measurement technique. There is value in further refining this, or another, performance test method to assess the influence of salt brine concentration on pavement friction.

The objective of this project was to synthesize available information on non-chloride deicers to allow for a more comprehensive understanding by winter roadway maintenance professionals and allow for easy comparisons between products and with sodium chloride (as salt brine or rock salt). This was accomplished through a literature search that summarized research on non-chloride deicing products and identified 46 non-chloride deicing products, summarized research on applications of various heated pavement technologies, and summarized research on anti-icing and anti-bonding/water-repellent surface treatments. Two surveys of state and local transportation agencies and vendors and manufacturers of non-chloride deicing products were conducted, respectively. The survey of state and local transportation agencies identified non-chloride products used. An evaluation of the Clear Roads Qualified Products List (QPL) Specification Document and other standards and testing requirements was conducted, which suggests that a wealth of data is collected and available for review of non-chloride deicing products. A deeper evaluation of BOD, COD, nitrogen, phosphorus, cyanide, toxicity, and corrosion is provided, because these are of particular interest when considering non-chloride deicers. Subsequently, we developed educational primers, or two-page fact sheets, for key categories of non-chloride deicers – acetates, formates, glycols, and ag-based that serve as high-level overviews of information on non-chloride deicers that can be used to make informed decision when comparing products to sodium chloride as rock salt or salt brine. This work found non-chloride deicers to be a viable option in winter roadway maintenance operations and many transportation agencies across the country are successfully using these products.