12/2/2008 12:00:00 AM<< Back to Facilities Management Grounds Management Category Home
Anti-icing vs. Deicing: Applying Industrial Snow Melter
Compiled by FacilitiesNet Staff
Historically, grounds care departments have removed snow and ice by overusing chemicals to complement the use of shovels, plows, and related equipment. In recent years, granular materials have become a popular and effective method for maintaining safe conditions during and after a storm.
Understanding the difference between anti-icing and deicing can give managers insights into the different approaches that can help them deal with ice efficiently.
Deicing is the reactive application of industrial snow melter to eliminate existing snow and ice on driving or walking surfaces. Deicing after snow removal operations can melt any remaining snow and ice.
Anti-icing refers to the proactive application of industrial snow melter to driving or walking surfaces before a storm. This tactic helps prevent snow and ice from bonding to the pavement, and workers can clear them away more easily. Used effectively, anti-icing can create some of the safest conditions in the winter and can be a cost-effective alternative to deicing.
Common industrial snow melter products include:
Sand. Although sand can provide some traction, it technically is not a deicing material, since it does not melt snow or ice. A common misconception is sand is the best alternative for snow and ice control, due to its low cost and common use. Managers also need to consider the potential environmental impact of sand.
Salt. Sodium chloride (NaCl), or rock salt, is a well-known industrial snow melter. This product generally is effective, though not in all conditions. In very cold conditions — typically below 23 degrees — salt begins to lose its effectiveness and either is not used or is overused in trying to make up for reduced performance.
Sand-salt mix. Another common practice is to mix sand and salt for deicing. This method is effective in maintaining some traction, due to the sand. But it reduces the amount of salt workers can apply to an area. As a result, less deicing occurs, while the environmental concerns and clean-up costs associated with sand rise.
Beyond Salt and Sand
Managers have other industrial snow melter options for deicing and anti-icing, and each offers differing levels of effectiveness, cost, availability, and environmental impact. These products include calcium chloride (CaCl), magnesium chloride, potassium chloride, urea, calcium magnesium acetate, and potassium acetate.
CaCl is effective as an industrial snow melter down to about minus-20 degrees. It is an exothermic salt, meaning it releases heat as it melts the ice. It melts ice faster than other common deicers, but it tends to attract moisture from the air even after melting the ice, causing pavements to remain moist. If the moisture refreezes, it creates icy conditions, and the ice expansion can cause surface damage. Wet-dry and freeze-thaw cycles lead to spalling, which means flaking or chipping. CaCl also can be more corrosive to metals, and it can cost more than other materials.
Magnesium chloride has many similarities to CaCl, including cost. It is exothermic and absorbs moisture from the air. This characteristic makes it a fast-acting industrial snow melter when applied as a solid and mixed with sand or salt. Crews also can spread it directly on pavement as a liquid before a storm arrives. In temperatures ranging from 15- to minus-20 degrees, it is more effective than NaCl but less effective than CaCl.
Many people believe potassium chloride and urea are safe products to use around vegetation, but this is a common misconception. Fertilizer is good for plants, but at high concentrations, it can be deadly. Urea does not contain chlorides, so it is less corrosive and safer for use on concrete containing rebar and around steel structures. Urea is effective to 15 degrees and potassium chloride to 12 degrees. Both materials work more slowly than calcium chloride.
Snow Removal: Cold-Weather Challenge, Hot-Button Issues by Brian Birch
Snow and Ice Removal: Deicing vs. Anti-icing by Brian Birch and Ellen Kobach
Maximizing Melters by Cathy Walker
How to Eliminate Rock Salt and Sand
Developing a Plan for Snow and Ice Removal