Section 5: Recommendations for Use of Liquid Chemicals
Using for Snow Storms
For snowstorms, initial liquid applications can be made either
as a pretreatment in advance of the storm or as an early-storm treatment,
(i.e. soon after snowfall has begun and/or when the pavement temperature
is dropping toward freezing).
Pretreatment
A pretreatment can be made prior to a storm, as long as the
storm does not start out with above freezing temperatures and rain,
washing the chemical away.
Benefits from liquid pretreatments can include higher friction
and better pavement conditions early in a storm. These benefits
are generally short-lived and should not be expected over a long
period. Subsequent chemical applications should be made as soon
as conditions begin to deteriorate. Pretreatments can be thought
of as "buying time" in the early stages of a storm until subsequent chemical
applications become effective.
Early-Storm Treatment
In the case of early-storm treatment, the application may
be made onto dry, wet, light slush, or lightly snow covered pavement. Late
applications onto pavements with more than a light covering of slush
or snow can result in excessive dilution of the chemical, lowering
its effectiveness.
Preventing Black Ice
To prevent the formation of frost or black ice, the chemical
should be applied before ice is expected to form so the water component
of the chemical will evaporate or be removed by traffic action. This will
leave only the chemical on the road surface and result in the greatest
concentration when frost or black ice conditions would otherwise occur.
Use Caution During Liquid Precipitation Storms
The use of a liquid pretreatment is questionable during an
event which has rain prior to freezing temperatures due to potential
loss of pretreatment material.