DECLARING WAR ON ICE!!!
Product knowledge can help find the right weapons:
Keeping the grounds safe for vehicles and pedestrians is a main concern when snow and ice accumulate. Use of deicing products is a common way to rid walks and roads from potentially dangerous ice.
There are hundreds of brand names for ice-melting products on the market. Not all ice melters are created equal, however, so they are not equally effective and safe to use. Take a close look at deicers before deciding which products are right for your site.
TYPES OF DEICERS
Did you know that 95% of chemical ice melters on the market are made from one or more of these five basic ingredients: sodium chloride, otherwise know as rock salt; potassium chloride and urea, which are fertilizers; and magnesium chloride , calcium chloride, sodium acetate, and calcium magnesium acetate, which are hygroscopic chemicals?
By knowing the properties of each raw material, you can decide more accurately which products will be most effective for your situation.
Rock salt is the most commonly used ice melter. It is inexpensive and melts ice. Compared to other materials, though, it has limited effectiveness in very cold temperatures. It will not melt ice at temperatures below 22 degrees and it may be harmful to vegetation, but is considered relatively safe for concrete.
Potassium chloride and urea are common fertilizers that are often perceived as safe products to use around vegetation. Urea does not contain chlorides, so it’s less corrosive and safer for use on concrete containing rebar and around steel structures.
Calcium chloride is a liquid brine in its natural state and is converted into a dry material by removing the water. It quickly absorbs moisture from the atmosphere, while rock salt, potassium chloride and urea must come in direct contact with moisture, which is not available at low temperatures. When calcium chloride is converted into a liquid, it gives off heat. Rock salt, potassium chloride and urea need heat to work. Calcium chloride will melt ice at temperatures of -25 degrees. Cost may be a prohibiting factor in the use of calcium chloride, sodium acetate or calcium magnesium acetate. Also, if applied to heavily, an oily residue may appear.
Magnesium chloride is very similar to calcium chloride. The major drawback to magnesium chloride is that it is only 48% active and needs to be applied at a greater rate than calcium chloride.
Ammonium-based ice-melting products like ammonium nitrate and ammonium sulfate are fertilizers. They are not recommended for use as ice melters, as they have been found to chemically attack and damage concrete.
Acetates — sodium acetate, calcium magnesium acetate (CMA) and potassium acetate — are environmentally friendly, biodegradable and non-corrosive.
Sodium acetate and CMA is a dry formulation used as an ice melter on bridges, parking decks and airport runways. It does not attack rebar in reinforced concrete and is biodegradable, creating no problems in runoff water. It changes ice and snow into a oatmeal texture. This is not desirable for sidewalks, and it also may be cost-prohibitive, as it costs four to five times more than calcium chloride.
PROMISE vs. PERFORMANCE
Don’t be misled by advertising claims. Catchy names, colorful packaging and impressive statistics can lure you to buy ice melters that may not meet expectations. Here are some common claims that may be misleading:
“Scientifically proven to melt at temperatures to -5 degrees”. This may be true, but this is a laboratory measurement taken in a controlled environment, not a practical ice melting temperature. In a laboratory, a liquid with a 10% concentration of salt will freeze at 20 degrees, a 20% solution will freeze at 2 degrees, a 23% solution will freeze at -5 degrees, and a 26% solution will freeze at -28 degrees. It’s not likely that you will create an exact 23 percent concentration of salt out on the sidewalks.
The practical ice melting temperature is one at which visible ice melting occurs within 15 minutes of application. Temperatures given previously were the practical melting temperatures.
Most ice melters state they will not harm vegetation when used according to label directions. This can be misleading because there are too many variables in the amount of ice melter used. How much snow and ice must be removed? How many times per year will ice melter be applied? Where does the melted snow and ice go?
Here are the results of a study of common deicing chemicals on turf.
- Sodium chloride generally is recommended for use at a rate of 1/2 cup to 1 cup per square yard. Damage to turf occurred with two to three applications and in one application if over applied.
- Salt also can kill the roots of plants, not just burn foliage. Sodium Chloride should not be used in area where melted runoff water will come in contact with sensitive plant material. Also, salt continues to build up in the soil, resulting permanent damage.
- Fertilizers often are assumed safe for turf because they are fertilizer. The rates for fertilizers used as ice melters, however, are much higher than the rates for feeding. Damage could occur is over applied.
The study also showed that blends of salt and fertilizer also caused damage to vegetation.
Many ice melters claim to be non-tracking. If they melt ice and snow, they create slush, and it tracks into facilities, no matter what. Look for an ice melter that is easy to clean up. Calcium Chloride is the hardest to clean when it is tracked on carpets. Using floor mats also will help lessen the problem.
According to the Concrete Institute, damage to concrete is primarily the result of freeze/thaw cycle on poor quality concrete. The chemicals sodium chloride and calcium chloride have very little effect on concrete. Ice melters, however, do increase the number of freeze/thaw cycles in a given season.
Ice melters also can damage concrete containing rebar. When chlorides in the brine seep into the concrete and come in contact with the rebar, corrosion begins, resulting in concrete cracking and spalling. For this reason, chlorides are not recommended for use on concrete containing rebar or around steel structures.
Some ice melters contain corrosion inhibitors, but these products have not always proven effective. These products do not act on the chloride ion in salt, but instead, work by pacifying the rebar. In a laboratory test, a bare metal strip is placed in a solution of ice melter with corrosion inhibitor and water. No corrosion occurs because the pacifying agent moves freely in the water and coats the metal. In the real world, the pacifying agent does not move freely; instead, it becomes tied up in the concrete and is not likely to reach the rebar.
The major considerations for choosing ice melters are:
- melting temperature
- product formulation
- application method
- types and uses of pavement to be cleared
- nearby vegetation and water
- interior floor surfaces
Don’t forget, however, to also look at product availability in quantities both large and small, lead time necessary for delivery, and container size and type for safe and efficient storage, handling and disposal.
Finally, take time to speak with a knowledgeable sales representative to discuss specific site needs and determine the most effective, safe and economical products.