Does Sand Melt Ice?
The short answer to the question “Does sand melt ice?” is “no, but it can affect ice.” Sand, working together with the sun or friction, can prevent or remove ice build-up.
Sand, by itself, does not change the freezing temperature of ice. If you add sodium chloride (rock or table salt) like what we have in the ocean, water can remain a liquid at lower temperatures. That is why sea water does not freeze until 28.4°F. If your freezer is at 20° and you throw a whole bunch of salt on ice cubes inside your freezer, you will come back to water instead of ice cubes. If you instead throw sand on top of the same ice cubes, you are going to get nothing, nodda, zip, zilch, goose eggs, AND a whole bunch of nothing but sand covered ice cubes hours later.
So, why do we see municipalities and companies use sand on ice?
There are a few benefits to using sand in icy conditions. First off, sand helps create better traction on the ice. Especially in really cold areas where, even with rock salt, the ice will not melt, the sand allows tires to have more friction against the ice for better traction.
The friction of the sand against the water on a busy road will also keep the water churning and prevent icing at temperatures near freezing.
Another reason sand is used is that the sand on top of the ice will absorb the sun’s heat and help melt the ice quicker than with no treatment of the ice at all. You can see how this works if you have ever seen a leaf that is sitting on top of snow. The leaf will melt into the snow, leaving a leaf shaped hole in the snow. The leaf, warming up from the sun’s rays, allows for the snow underneath to melt quicker than the snow surrounding the leaf.
A third benefit from sand is that the sand does not add more salt (sodium chloride) to the freshwater habitats near roads. It does not take a lot of salt to infect fresh water habitats leading to a changed ecology of the water. One of the biggest concerns in the Snow and Ice Management industry today is how to reduce salt use to minimize environmental damage. We need to keep the roads safe, but we don’t want to hurt our waterways unnecessarily either.
This does not mean sand does not have its own problems. Too much sand accumulating where it does not belong can also hurt the environment. When the sand is dry in the spring and summer, sand can also create a hazardous situation where you have less traction than traction on clean asphalt. Too much sand on a curve can be especially dangerous for motorcycles with only two wheels that are relatively close together as compared to a car.
Why do I sometimes see sand melt ice on winter nights if it doesn’t change the melting point?
If you see sand melting ice, you are probably looking at a sand & salt blend instead of just plain sand. A common tactic snow and ice management professionals use is mixing sand and rock salt together to apply on surfaces. The salt will lower the melting point of the water (as low as 15°for rock salt and even lower for premium road salts) while the friction caused by vehicles driving over sand also impedes the formation of ice. When ice does form, the sand is still there to add traction and the salt still does its work to lower the melting point of the ice.