There are two distinct snow and ice control strategies that use chemicals:
de-icing and anti-icing. They differ in the fundamental objective. Anti-icing is the practice of
applying deicing materials at the start of onset of a precipitation event in an attempt to prevent
or weaken the bond of ice to the pavement by reducing the freeze point of the water. As a result,
roadways stay wet or slushy, making snow and ice removal easier. (Freeze point is the temperature
at which a chemical/water solution begins to freeze.
De-icing is an operation where a treatment of a de-icing chemical is applied to the top of an
accumulation of snow, ice or frost that is already bonded to the pavement surface. De-icing is
familiar in most agencies since it has been the most widely used strategy in the past.
The biggest disadvantage of de-icing is that it is a reactive strategy. It is commonly initiated
after an inch or more of snow has accumulated and bonded to the road. By then, safe travel
conditions have often deteriorated. Today, proven anti-icing strategies are being used by many
transportation agencies as a proactive, preventative strategy.
|
