“How are the roads?” is a question that is heard almost as often as how is the weather in Wisconsin but how are the roads kept safe during winter? Not only does Wisconsin have a fleet of over 700 trucks for snow removal, the county department uses a wide variety of chemicals and techniques to keep roads clear and travelers safe.
During the winter of 2016-17, 63 counties in Wisconsin used a technique called anti-icing. Anti-icing is a preliminary step that crews can take before a storm to save time by reducing the effort need to remove the snow and ice. This technique prevents the formation of frost and the bonding of snow to the pavement. The materials used are applied before or early during a snowstorm.
Pre-wetting is another technique that is widely used. This is the addition of chemicals such as calcium chloride, magnesium chloride, salt brine or others to salt and sand. This helps keep the mixture on the road which in turn reduces the amount of material needed. This accelerates the activation of the chemicals before being applied to the road.
De-icing used chemical or mechanical means to break down the bond that has formed between the ice and the pavement. This technique involves plowing and continual application of chemicals and abrasives. For example, in Alaska a steel drum with spikes is attached to the front of a maintenance truck to break up the ice and expose the asphalt.
With the different types of techniques being used are paired with a variety of different chemicals in order to make them the most effective. The most common of these would be chloride-based deicers. These are typically the most common because of cost and availability.
Sodium Chloride, also known as salt, is the most common deicer used across the US. Crews in WI use an average of 526,000 tons of salt per season statewide. Sodium Chloride can be used in its granular form or used to make brine, liquid sodium chloride, which you can then add additives to improve its performance. This is critical because Sodium Chloride in its granular state is only effective down to a pavement temperature of 15-20 degrees. In fact, salt is most effective after snow has accumulated about an inch and the temperature is 20 degrees or higher. This is because there must be moisture on the road for freezing point depression to work. Freezing point depression is when rock salt lowers the freezing point of the water, making it more difficult to freeze.
Magnesium Chloride has a melting pavement temperature of -10 degrees. Magnesium Chloride has many of the same qualities as Calcium Chloride and is widely used by the DOT to pre-wet salt. This became common practice in 2006 because Calcium Chloride was not readily available. It is also less costly and overall, more effective. The DOT currently uses a 30% solution of Magnesium Chloride. When the salt is pre-wetted with this material is absorbs water from the air, dissolves the salt more quickly, and creates the brine that melts the snow and ice. Although, Magnesium Chloride is corrosive it remains the most effective and economical material for maintaining safe winter roads.
Calcium Chloride can be used as a deicer in its flake and liquid form. It has a melting pavement temperature of -20 degrees and is commonly used to enhance Sodium Chloride’s effectiveness. It has been shown that calcium chloride/rock salt mixtures also help clear roads faster than rock salt alone at temperatures near 30 degrees. Along with this Calcium Chloride has many more advantages as an additive to rock salt. The brine remains active for longer periods of time, has a much lower melting temperature down to -25 degrees, releases heat as it melts, speeding up rock salts melting ability and forms brine more rapidly.
On average in Wisconsin snowfall ranges from about 40 inches to as much as 160 inches and with about 113,000 miles of road in Wisconsin its important to keep the roads clear. It has been found that deicing roads reduces accidents by 88 percent. In order to make sure that you have all that you need to keep your roadways clear make sure to contact your ChemCeed representative for all of your needs.