Adding calcium chloride to de-icing salts reduces the negative impact of de-icing solutions on the environment, says new research done by the Swedish National Road and Transport Research Institute (VTI).
Salt spraying is essential to keep roads safe during wintertime. However, when the excessive amounts of salt migrate from road to a surrounding environment, salt absorption negatively impacts the soil, vegetation and groundwater, causing reduced soil permeability and fertility. Salt entering groundwater systems is likely to persist for a long time, since groundwater moves slowly.
When added to de-icing salts, calcium chloride forms a sticky layer, thereby keeping the salt “trapped” on the road and preventing its migration to environment. Thanks to its other properties, calcium chloride also makes the de-icing solution stay longer on the road. As a result, less salt is needed to keep the road surface safe, which makes it an attractive solution to reducing road maintenance costs.
The study, presented at the International Winter Road congress, draws attention to the effective economic and environmental contribution of using calcium chloride for de-icing. Held every four years, the congress unites professionals working on winter road safety from all over the world to enable the sharing of knowledge and best practices.
Study: Effectiveness of combinations of de-icing salts with NaCl or CaCl2 brines for friction control on roads. Kalman, B. Pavement Technology, VTI, Sweden.