Rock salt loses effectiveness at deicing roads in temperatures below 15 degrees Fahrenheit (F), so it’s common for winter maintenance teams to combine salt brine with an alternative deicer. MnDOT, for example, uses potassium chloride, magnesium chloride, and calcium chloride to melt roadway ice at colder temperatures.
However, operators lack concrete information and data on making the best use of alternative deicers and have had to rely on past observations, hunches, and vendor recommendations for application. This can be particularly problematic in colder regions of the state, where maintenance teams fight against refreeze due to dropping temperatures or diluted deicer concentration.
In a recent project from MnDOT and the Minnesota Local Road Research Board, researchers set out to examine the freeze point, ice melt capacity, and field performance of the most common alternative deicer used by MnDOT and county transportation agencies. Investigators evaluated varying ratios of the deicer with rock salt in both the laboratory and the field to get a clear picture of how well it works under different conditions.
Notably, the study found that the alternative deicer softened the road surface snowpack at temperatures between 15 and -20 degrees F. This led researchers to suggest a practice of softening the snowpack with deicer and then plowing to clear the roads at colder temperatures, rather than relying on salt and alternative deicers alone.
Whereas winter maintenance managers once had to rely on anecdotal evidence, these findings offer instruction for the best use of alternative deicers to enhance their effectiveness on the road. To learn more, the final project report, research summary, and accompanying blog posts are all available to view online.
