How Driveway De-icer Salts Work

Throughout the winter season, you need to be ready to treat your driveway and walkway areas, such as front steps, with something to either melt ice or provide extra traction to make it safe to walk.

De-icing salts are commonly used, but how do they work? How can something that is not hot melt ice in sub zero temperatures?

Salt doesn’t actually attack the ice to melt it. It lowers the freezing point of water below zero degrees celsius, a process called freezing point depression.

Salt is comprised of ions that penetrate water molecules keeping them from forming ice crystals. This only works if there is some water on the surface of the ice for the salt to react with. Fortunately, driveway ice typically has surface water, from warmer air or the sun hitting it, so the salt can get to work.

Ordinary salt, sodium chloride, does a good job melting ice at temperatures above -10 celsius, while other salts such as magnesium chloride or calcium chloride work fine at even lower temperatures.

Here’s a video about the science behind de-icing salts.



Salts can cause some problems however. Concrete surfaces are prone to damage by salts which cause surface cracks and flaking. Plants located around your driveway or front yard gardens can become dehydrate and damaged because of salt.

Pets walking on salt laden ice water can end up with sore dry paws, so make sure you wipe off your dogs paws if it comes into contact with salt water.

You can reduce the chance of damaging your concrete steps or asphalt driveway by using a moderate amount of de-icer combined with a traction material like sand or kitty litter. Acetate products can break the bond between the aggregate and the asphalt binder so those types of de-icers should be avoided.

Here is a consumer report about rock salts and other de-icers, comparing the different types, risks, and effectiveness.

Although we’ve had a mild November, it’s time to get ready for winter and purchase some bags of de-icer for the months ahead. De-icers can have their risks, but they are effective at reducing ice and making our homes safer.

By: Chris Ferreri

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