There are several different salt options when a road or path is gritted by a grit salt spreader. Halite, or rock salt, is most commonly used by councils in the UK, but GRITIT uses white marine salt to melt ice. Why would GRITIT choose to use a different type of salt for its gritting and snow clearance?
Rock Salt For Gritting
Halite, or grit salt, is a form of sodium chloride, the same chemical compound as the table salt that we use to flavour our food.
Rock salt grit was laid down in the ground many aeons ago, and is the product of prehistoric seas drying up. In the UK, rock salt is mined in Cleveland, County Antrim and below the Cheshire town of Winsford.
Rock Salt is approximately 94% sodium chloride, and has a characteristic reddish-brown colour owing to the presence of marl (an insoluble mineral) which is the chief impurity.
Of the total salt production in the UK, 30% is used as rock salt for de-icing roads.
This brown rock salt certainly has an advantage in that it is relatively cheap, but:
- Rock salt it can be harmful to vegetation, especially in high concentrations;
- Rock salt leaves a messy brown residue; and
- Rock salt is not as effective at dissolving snow and ice compared to white salt
However, rock salt has a strong tendency to cause corrosion, rusting the steel used in vehicles and the rebar in concrete bridges.
Depending on the concentration, it can be toxic to some plants and animals, and in the USA, many urban areas are moving away from rock salt as a result.
Marine Salt For Gritting
White marine de-icing salt is the most concentrated and effective salt as it is 99.9% sodium chloride.
It keeps our carpets and clothes cleaner than brown salts, and as it is completely soluble, there are no impurities or grit to clear way afterwards or to block our drains.
The biggest plus is that it is kinder on our environment because it is more sustainable than rock salt that is mined.
We occasionally have queries after spreading marine salt because it can’t easily be seen the next morning, like the more traditional salt and grit. When there is a lot of moisture for example, either in the air or on the surface being treated, the salt will dissolve quickly and you won’t be able to see it. However, the salt is busy working as it is this marine salt, now in a concentrated saline solution, that lowers the freezing point of water to prevent it from freezing.
White marine de-icing salt is the GRITIT salt of choice because:
- White marine de-icing salt is easy to spread over snow and ice;
- White marine de-icing salt quickly dissolves;
- White marine de-icing salt does not leave a colour or residue to clean up; and
- White marine de-icing salt is the best solution for areas where cleanliness is important such as retail outlets, schools and hospitals