The most widely solicited use of rock salt, solar salt and vacuum salt in developed countries comes from highway de-icing applications.
Ideally, the rock salt, solar salt and vacuum salt should be applied on the points where there is snow or ice, but doing it in previous points is more efficient, as it allows for the creation of a layer of Brine that due to its lower freezing point, will melt the ice more quickly.
On roads salt must be laid at points where there is snow or ice, but it is more efficient to lay it at points next to the ice, as that allows a layer of brine to build up. Since it has a lower freezing point it makes the ice melt more quickly.
