Ice Melt or Rock Salt? What’s the Difference?

There are many differences between ice melt and rock salt, but the source of these differences is in their chemical composition.

Footprints in the snow

Let’s take rock salt first...

When a rock is primarily composed of Halite (sodium chloride), more commonly known as salt, it is referred to as rock salt.

When combined with grit and gravel to create the grit salt we use in winter, it is the sodium chloride (salt) which penetrates the ice and dissolves with the water to form a brine solution.

Because the freezing point of this brine solution is lower than water the ice begins to melt.

Now ice melt...

There are different ice melt products available and they are primarily composed of magnesium chloride, sodium chloride, calcium chloride and potassium chloride.

Glasdon Icemelt™, for instance, contains magnesium chloride with sodium chloride and limestone.

Through a process of freezing point depression, the Icemelt solution works much in the same way as traditional rock salt. However when dissolved with the water, magnesium chloride solution has a much lower freezing temperature than the brine formed from rock salt and water alone.

So, ice melt or rock salt?

To help you decide which gritting and deicing solution is the most suitable for your requirements, we've compiled some key considerations and performance outcomes of ice melt and rock salt below.

If you would like any further help or information or you would like to talk to someone about your winter safety requirements, please don't hesitate to contact our team or live chat with us today.

Ice Melt versus Rock Salt

Key ConsiderationsPerformance
SpeedIce melt is extremely fast acting as the magnesium chloride is more hygroscopic than rock salt. This means it attracts and absorbs water molecules much faster and so the solution works on melting ice and snow far quicker.
TemperatureRock salt lowers the freezing temperature of water to around -9°C. Ice melt lowers the freezing temperature down to around -15°C providing an effective and longer lasting solution in severe conditions, continuing to weaken ice and snow assisting with clearing.

Ice melt is a fully biodegradable fertiliser, combined with a naturally forming rock for added grip. It has less of an effect on the environment, whereas excessive exposure to salt is known to be harmful to plants, lawns and soil beds.

Ice melt also leaves little residue around which is important for areas of high footfall.

StorageBoth rock salt and ice melt can be stored in a grit bin to keep it sheltered from the elements and located in priority areas on site, so it is ready when you need it.
SpreadingDue to the coarse nature of rock salt, heavy duty equipment and regular maintenance is required. Take a look at our guide on how to keep your grit spreader in perfect working order, to find out more.
CostOne of its only benefits, rock salt is cheaper when covering large surface areas.

Winter Safety Checklist

Monday, September 25, 2017
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