Why is
Salt used? Salt is
used as the principal de-icer because it is has historically
been the most readily available and most cost-effective
choice. The primary type used is Rock Salt that is mined
from the earth. Salt is used to keep snow and ice from
bonding to the pavement and to allow snowplows to remove
accumulations quickly and efficiently.
2.
How
Does Salt Work?
When salt is applied to ice and snow, it creates a brine
that has a lower freezing temperature than the surrounding
ice or snow. To date, Salt has been the most commonly
used de-icing product because it is:
readily available
the least expensive de-icer
relatively easy to store and
handle
easy to spread
relatively harmless to skin and
clothing
believed to be harmless to the
environment when used and stored properly
The use of salt for winter maintenance
is based on the fact that dissolving one substance
in another alters the freezing point of the second.
Salt lowers the freezing point of water. The greater
the concentration of salt, the lower the freezing
point, although there is a limit of temperature below
which salt will not melt ice. This is called the eutectic
point (-21degrees C).
Melting begins on contact when salt
is spread on ice or snow. This produces water, dissolving
more salt and producing further melting. The rate
of melting will depend on the surrounding air and
ground temperatures. Other influences on melting rate
are the particle size of the salt and the amount of
mixing often caused by traffic.
3.
How
De-icers Work?
De-icing chemicals get ice off pavement by lowering
the melting point of the ice. The de-icer and ice
form a liquid brine and remain in a liquid form at
temperatures where pure water would freeze. The liquid
brine also seeps between the remaining ice and pavement,
breaking the bond between the ice and pavement for
easier plowing. The following are some de-icing products
and techniques in use today:
Sodium
Chloride, also known as rock salt, is the cheapest
and most commonly used de-icing product. It is produced
in various particle sizes. The larger of these are
used for roadways, then progressively smaller for
parking lots and sidewalks. It will work to -7 degrees
F, although it is most effective around 10-15 degrees
F.
Calcium
Chloride, often used during very cold weather
conditions because it can continue to work to -60
degrees F, but is often considered most effective
around -25 degrees F. More expensive than rock salt.
Calcium
magnesium acetate (CMA), is an alternative
de-icer with minimal corrosive properties. CMA can
be quite expensive, often more expensive than calcium
chloride.
Blended
products are relatively new on the market,
with different compositions offered by various manufacturers.
The advantages to using blended products include reduced
use of sodium chloride, and utilizing the strengths
of particular chemicals to maximize aspects of other
de-icing products, such as melting rate and melting
capacity.
Important
Notice: This information is provided
by Draglam Salt as an educational convenience only without
warranty of any kind. Draglam in no way guarantees the
completeness or precise accuracy at any given time.
Please consult your manufacturer for specific details
on a de-icing products and their performance statistics.
