For anyone living on the south side of their street, the existence of an icy front walkway can be a daily frustration. Ice from freezing rain of the melt and refreeze of snow can make your front walkway and steps treacherous. Here is a bit of the science of the most common cure to ice: rock salt.

Rock salt, known scientifically as sodium chloride or halite, is the most commonly used ice melter in North America due to its prevalent availability and low cost. It provides adequate economical performance at temperature close to freezing, but as temperatures drop below freezing, its performance slows substantially. Below temperatures of -8 degrees Celsius, rock salt has little to no ice melting abilities.

One surprising fact that very few people know is that salt does NOT melt ice! The way the salt has ice melting abilities is by mixing with available moisture in the air and from snow to create a salt water mixture called brine. This brine forms between the ice and the pavement (or walkway/concrete) and initially breaks the bond between the ice and the pavement allowing the ice to be more easily removed by plowing or shoveling. Over time, the brine will continues to melt the ice from the bottom until either the ice is gone or the concentration of salt in the brine is too low to be effective at the current temperature. When the concentration of the brine gets too low, there is also a tendency to experience re-freeze, where the brine itself will turn to ice. Along with the dangerous effects that re-freeze can have (sometimes resulting in glare ice or conditions similar to freezing rain), rock salt also has toxic effects on plants and can cause damage to uncured or low strength concrete. On a larger scale, the road salt used in plazas, on municipal roads and on provincial highways has huge impacts on ground water and lake salinity. This is a huge environmental issue but due to the liability of not using salt (auto accidents, slip-and-fall accidents) its use will continue until a suitable replacement is found.

There are many alternatives to rock salt that can be considered. Calcium chloride and magnesium chloride on their own, or mixed with rock salt are excellent de-icers that melt ice faster and at lower temperatures and are readily available at all the home stores. Many ‘enviro’ de-icing products exist that are less toxic to plant material (and the environment) than rock salt, but some only marginally. One of the most environmentally friendly options to deal with ice (aside from wearing skates) is to spread pickled sand on the area to provide traction and some minor melting. Pickled sand is sand that has been treated with a small amount of deicing agent (sometimes salt) to keep it from freezing in the winter. You will have a bit of a sandy mess to clean up in the spring, but at least your walkway/driveway/parking lot will be safer.

The best way to reduce the buildup of ice is to remove snow promptly after a snowfall. Also, spreading a small amount of de-icer before a large snowfall will make it easier to shovel/clear/plow right down to the bare pavement/concrete.

For questions about residential or commercial snow and ice management please contact us at snow@ryanheath.com

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