Salt Brine 101
Salt brine (a freeze-point depressant) is a relative newcomer in the department’s arsenal against ice and snow, which also includes an advanced equipment fleet, salt and sand. The region adopted the use of salt brine about five years ago, as a result of the rising cost of magnesium chloride, which had been used before.
What it is
The salt brine solution is made up of water mixed with 23.3 percent sodium chloride. Because corrosion from salt presents a problem for roadways, the department adds an organic compound to the mixture that makes the solution one-third as corrosive as salt. The additive also lowers the effective temperature of the salt brine solution.
What it does
The salt brine mixture features in the department’s anti-icing measures. Anti-icing involves treating bare roads before a winter storm event with the solution to slow or prevent the build-up of snow and ice. Salt brine applied before a storm forms a bond breaker between the pavement surface and the snow and ice layer reducing the chances that ice will form and bond to the pavement surface. Northern Region used to focus solely on de-icing but has since incorporated a more proactive anti-icing strategy.
When it’s used
Timing plays an important role in the effectiveness of anti-icing measures. The salt brine solution works best when applied before snow and ice accumulate on roadways and at temperatures of 20 F and above. Another key factor in deciding on whether the anti- icing solution will be applied is pavement temperature. To be effective in combating ice, salt brine should be applied on pavement temperatures of +15 F or higher.
Once snow and ice have accumulated, crews switch to de-icing measures. Salt brine can still be used, but instead of being applied directly, the mixture is sprayed onto sand as it is applied by sand trucks to roadways. This process makes the sand penetrate the ice better as well as aiding in the reduction of sand scatter from the traveled roadway. Pre wetting our sand before application has shown to reduce the loss of sand off the roadways, thus reducing the amount of sand applied.