Roads: Dust Control

First, determine the amount of dry calcium chloride to mix with water using our helpful Making Solutions Calculator tool.

Always start with cool water and add the solid calcium chloride slowly to the water while continuously mixing. Significant heat is released when dissolving solid calcium chloride, and a temperature increase will occur. For example, when dissolving DOWFLAKE®  Xtra 83-87% Calcium Chloride Flakes while making up a 30% solution, the temperature can be expected to increase almost 84°F.

If solids are allowed to sit motionless while in contact with water, a hard cake will form that will be slow to dissolve.

Please consult our Diluting Solutions Calculator, which covers three different options:

1. Diluting with water
2. Diluting with a lower concentration calcium chloride solution
3. Diluting with both water and a lower concentration calcium chloride solution

The pH reading for an undiluted sample of 35% solution is approximately 9. OxyChem calcium chloride products are alkaline due to the presence of a slight calcium hydroxide impurity.

Accurate and consistent pH measurement in concentrated salt solutions can be challenging. Results vary depending on the pH probe used and the degree of sample dilution.

No, OxyChem does not have a calcium chloride dihydrate product. DOWFLAKE® Xtra is the closest to a dihydrate concentration.

Calcium chloride dihydrate has two water molecules for every one calcium chloride molecule, giving an overall calcium chloride concentration of 75.5%. OxyChem’s DOWFLAKE® Xtra product contains a minimum of 83% calcium chloride, making it more concentrated than the calcium chloride dihydrate flake on the market. 

Store product in a dry area, and tightly reseal after each use. To maintain product quality while in storage, solid calcium chloride must be protected from moisture. If the product is on a pallet covered by an intact plastic shroud, it can be stored outdoors on a well-drained surface. If the shroud is torn, pierced, or removed, the palletized product should be stored indoors or under a waterproof covering.

For additional information, see our Calcium Chloride Handbook.

The preferred material of construction for large liquid storage tanks is carbon steel with an epoxy-based interior coating and a durable, high-quality coating on the exterior. Non-metallic materials, such as fiberglass or plastic, work well for smaller tanks storing product at ambient temperature; however, these materials are not as durable as carbon steel, and they lose strength at high temperature.

Common stainless steels are not recommended for liquid calcium chloride storage as they are subject to chloride stress corrosion cracking, even at temperatures as low as 100°F (38°C).

For additional information, see our Calcium Chloride Handbook.

When properly stored to protect from moisture contact, the expected shelf life for solid calcium chloride products is 36 months from the date of manufacture. Calcium chloride does not degrade or deteriorate; however, the shelf life is limited based on the potential for moisture intrusion into the product, which may cause product clumping. Solid calcium chloride absorbs moisture from the air (i.e., is hygroscopic), even to the point of converting to liquid brine (i.e., is deliquescent).

Effective dust control is built first on a foundation of quality gravel and proper road maintenance. Road construction experts can help you determine the proper foundation for your needs. 

Recommended calcium chloride application rates to control dust on gravel surfaces are included below. NOTE: When applying solid products, it is usually preferable to water the surface prior to spreading the product.

The most desirable calcium chloride product for any given situation is a matter of personal choice. Solid calcium chloride products may be spread directly or dissolved in water and spread as a liquid. In the U.S., the most common liquid concentration used for dust control is 38%. In Canada, the most common concentration is 35%. Liquid concentrations higher than 38% may be used; however, higher concentrations are more likely to crystallize as the solution cools. 

To maintain optimum dust control during unusually long periods of hot, dry weather, water the road surface during early morning hours as needed to reconstitute the initial treatment. Re-apply calcium chloride in the late summer or early fall as needed to prolong dust control.

For additional information, see Use Responsibly - Controlling Dust. 

Noticeable corrosion is unlikely to occur on vehicles driven on unpaved surfaces treated with calcium chloride. However, calcium chloride for dust suppression is present in small amounts and can stay bound in the soil in the road. Therefore, it is recommended to wash vehicles and equipment if you suspect the vehicle has encountered calcium chloride.

Likelihood of damage to vegetation and grassy areas along roadsides can be significantly limited if dust control applications follow current recommendations and standard practices.

For additional information, see Use Responsibly - Managing Impact. 

A 2008 study by researchers at Colorado State University¹ and a report by the U.S. Department of Agriculture Forest Service² concluded that the impact of magnesium chloride is no less than other chlorides.

The chloride content of liquid material is determined by the concentration of the solution, and the molecular weight of the salt. For example, a 30% solution of magnesium chloride has about the same chloride content as a 35% calcium chloride solution.

Equally important in determining environmental impact is the application rate of the product. A more concentrated product can achieve the same results at lower application rates. While magnesium chloride is commercially available in 30% solutions, LIQUIDOW® is typically applied at concentrations of 35% or 38% for dust control and road base stabilization applications, which means less calcium chloride may be required to achieve the same result. 

For additional information, see calcium chloride vs. magnesium chloride.

¹Condition of Soils and Vegetation Along Roads Treated with Magnesium Chloride for Dust Suppression, B.A. Goodrich, R.D Koski, and W.R. Jacobi, March, 2008.

²Dust Palliative Selection and Application Guide, USDA Forest Service, P. Bolander and A. Yamada, November, 1999.