Frequently Asked Questions

There are many claims made about dust suppressants and gravel stabilizing agents, but separating misinformation from the facts can be difficult. Following are some frequently asked questions we receive about dust control technologies and factual answers that will help dispel myths and make it easier to make informed choices. For answers to more general questions, see more FAQs on the OxyChem calcium chloride main website.* 

Is liquid magnesium chloride lower in chloride and safer for the environment than calcium chloride?
What are the application guidelines for using calcium chloride to control dust on gravel surfaces?
Is calcium chloride safe for use around grassy areas and other vegetation?
Is calcium chloride used for dust control corrosive to vehicles?
How do I make solutions by mixing solid calcium chloride products with water?
How should packages of solid calcium chloride be stored?
What materials of construction are recommended for storing liquid calcium chloride solutions?

Q: Is liquid magnesium chloride lower in chloride and safer for the environment than calcium chloride?

A: No. 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 would have about the same chloride content as a 35% calcium chloride solution. 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. 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. This is supported by best practices published by Environment Canada recommending an application rate of 1.4 to 2.3 l/m2 of magnesium chloride to achieve the same dust suppression capability as calcium chloride applied at a rate of 0.9 to 1.6 l/m2.3 The USDA Forest Service found that a magnesium chloride application rate of 0.30 to 0.50 gal/yd2 was necessary to achieve the same dust suppression performance as 0.20 to 0.35 gal/yd2 of calcium chloride.2

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.

3Best Practices for the Use and Storage of Chloride-based Dust Suppressants, Environment Canada, February, 2007.

Q: What are the application guidelines for using calcium chloride to control dust on gravel surfaces?

A: Various forms of calcium chloride have been used to control dust on gravel roadways for over 100 years, improving safety and comfort for travelers while reducing maintenance costs for road managers.

The most desirable 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. Learn More.

Q: Is calcium chloride safe for use around grassy areas and other vegetation?

A: Under typical application conditions, calcium chloride will not damage grass or vegetation adjacent to a road surface where dust control is applied. As with fertilizer and any other road dust control chemical, it is possible for grass to be damaged if the calcium chloride is over-applied or large quantities are directly applied to grass or vegetation.

Q: Is calcium chloride used for dust control corrosive to vehicles?

A: Noticeable vehicle corrosion is not likely to be associated with dust control applications of calcium chloride. First, the application rate is relatively low, so there is not much calcium chloride available to come into contact with passing vehicles. Second, the calcium chloride tends to remain in the road bed. If it didn't, it wouldn't control dust very well because it would disappear from the road after a short while. If it is suspected that a vehicle has come into contact with calcium chloride, a basic wash of the vehicle will remove this highly soluble salt.

Q: How do I make solutions by mixing solid calcium chloride products with water?

A: Use cool water when creating solutions. Significant heat is released when dissolving solid calcium chloride. Add solid calcium chloride slowly while continuously mixing. If solids are allowed to sit motionless while in contact with water, a hard cake will form that will be slow to dissolve.

Temperature increase while the solid calcium chloride is dissolving will vary depending on the conditions associated with each specific application. However, a rough estimate may be calculated as follows: For DOWFLAKE™ Xtra 83-87% Calcium Chloride Flakes, assume a temperature increase of 2.8°F per percentage increase in concentration. For example, when making up a 30% solution from DOWFLAKE™ Xtra 83-87% Calcium Chloride Flakes, the solution temperature can be expected to increase approximately 84°F (30 x 2.8°F = 84°F ).

Use our helpful Making Solutions Calculator tool, to determine the amount of dry calcium chloride to mix with water to achieve solutions of various concentrations.

Q: How should packages of solid calcium chloride be stored?

A: Solid calcium chloride is both hygroscopic and deliquescent. This means that the product can absorb moisture from the air, even to the point of converting to liquid brine. For this reason, protecting solid calcium chloride from excessive moisture exposure is the primary requirement to maintain product quality while in storage.

Opened packages should be tightly resealed after each use to prevent caking and liquid brine formation that may result from exposure to humid air. They should be stored in a dry place. Some types of bags do not seal well if stored standing on end, therefore unopened packages should be stored lying flat in a dry area. Avoid storing in areas where product leakage could cause damage.

Palletized product covered by an intact plastic shroud may be stored outdoors on a well-drained asphalt or concrete surface. If the shroud is torn, pierced or removed, the palletized product should be stored indoors or under a waterproof covering. Products packaged in drums or FIBCs (aka. Super Sacks or Big Bags) are typically not shrouded. Therefore, these packages should be stored indoors or under a waterproof covering.

Solid calcium chloride is temperature-stable under all ambient storage conditions.

For additional information, see Calcium Chloride: A Guide to Handling and Storage.

Q: What materials of construction are recommended for storing liquid calcium chloride solutions?

A: 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.

For additional information refer to the publication, Calcium Chloride: A Guide to Handling and Storage.

*This information is not intended to be all-inclusive as to the manner and conditions of use, handling, storage, disposal and other factors that may involve other or additional legal, environmental, safety or performance considerations, and OxyChem assumes no liability whatsoever for the use of or reliance upon this information. While our technical personnel will be happy to respond to questions, safe handling and use of the product remains the responsibility of the customer. No suggestions for use are intended as, and nothing herein shall be construed as, a recommendation to infringe any existing patents or to violate any Federal, State, local or foreign laws.