Corrosion – Effects of Deicers on Metal

Ice Melters are known to be corrosive to metal. Any ice melter containing chlorides will be corrosive to metal.

The Chemistry of Chloride Corrosion

The chloride ion molecules in the deicer interact with the metal in an electrochemical reaction which accelerates the metal molecule's interaction (oxidation) with the surrounding oxygen into metal-oxide molecules. This results in what is commonly called rust.

close up of oxidized iron

Metal corrosion is a concern primarily in parking garages, helicopter pads, and runways at airports. It is a concern in parking garages due to the steel rebar that is in the concrete to reinforce it. The Federal Aviation Administration prohibits the use of chloride deicers, keeping the aircraft from exposure to this corrosive material.

The common dry non chloride deicers that are used to avoid corrosion are CMA (Calcium Magnesium Acetate), sodium acetate and urea. The primary non chloride liquid for anti-icing use on pavement is potassium acetate. Note that none of these chemicals have the word “chloride” in them. We offer potassium acetate liquids in our Ice Guard and Select Liquid Deicer products.

“Less Corrosive” Deicer Claims

Some chloride based deicers are claiming to be “less corrosive”. These products contain 95 - 99 percent chlorides and have about one 1 percent CMA added. CMA costs about 20 times as much per pound as salt; this is why only a “pinch” can be added to a common deicer. We cannot find any evidence supporting the claim that adding any amount CMA to salt helps reduce the corrosiveness of chlorides. According to The National Research Council’s Transportation Research Board in their Special Report 235, “there is insufficient evidence to determine whether CMA reduces the rate of corrosion in concrete that is already contaminated with chloride”. As a result, we do not believe that spraying corrosion inhibitors on salt can effectively reduce the corrosiveness of salt. Therefore, it seems that the primary purpose in spraying corrosion inhibitors on chlorides is to help sell the product more than to significantly reduce the corrosiveness of salt. If you are still interested in a “less corrosive” product, we have on offer MAC.