DUST BINDING SALTS

The purpose of dust binding gravel roads is to keep the moisture in the road surface. Two salts are useful for this. If the relative humidity is more than about 35% they absorb moisture.

You can spread the salts as dry "Flakes" or you can dissolve the flakes in water and spread as a brine. Both salts have a better effect if they are spread as a brine.

Magnesium chloride has essentially the same effect as calcium chloride when it comes to dust suppression and moisture stabilization. However, when applied in flake form, it dissolves more quickly than calcium chloride and penetrates the surface more effectively, resulting in a faster action.

Another advantage of magnesium chloride is that it is non-irritating to the skin, making it particularly suitable for use in riding arenas, paddocks, and other environments where people and animals are in close contact with the treated surface.

When applied as flakes, magnesium chloride typically requires about 20% higher dosage compared to calcium chloride to achieve the same result. However, when used as a brine solution, the dosage is the same for both products, as confirmed by practical tests—making the end effect comparable regardless of which salt is used.

In practical applications for dust control on gravel roads in Sweden, a chloride concentration of 30–32% is typically used, regardless of whether magnesium chloride (MgCl₂) or calcium chloride (CaCl₂) is the active ingredient.

To achieve this concentration, the following mixtures are commonly used:

1 ton of magnesium chloride flakes with approximately 0.6 m³ of water, or
1 ton of calcium chloride flakes with approximately 1.5 m³ of water.

The result is a brine solution with a chloride content of around 30–32%, which has proven effective for dust suppression and surface stabilization of gravel roads.