2 FM quick reads on Anti-icing
1. Anti-Icing, Deicing Can Use Same Products
Today's tip is to understand the difference between anti-icing and deicing. Deicing is the reactive application of industrial snow melter to eliminate existing snow and ice. Anti-icing refers to the proactive application of industrial snow melter before a storm. This tactic helps prevent snow and ice from bonding to the pavement, and workers can clear them away more easily.
Although sand can provide some traction, it technically is not a deicing material, since it does not melt snow or ice. It is low-cost, but managers need to consider the potential environmental impact.
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. Mixing sand and salt for deicing maintains some traction, 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.
Other options for deicing and anti-icing include calcium chloride (CaCl), magnesium chloride, potassium chloride and urea.
CaCl is effective 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, causing pavements to remain moist. If the moisture refreezes, it creates icy conditions. 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. 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 to use around vegetation, but they are not. 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.