Significant threats of snow and ice will remain across much of Canada from January through March. For safety reasons, there is plenty of justification to use chemicals commonly referred to as "ice melt" or "salt" on roads, driveways and sidewalks.
Many towns and cities have their own local bylaws regarding mandatory snow and ice removal from sidewalks within a given time period following snow or ice events for both business and residential situations.
It is hard to argue against the importance of treating streets and sidewalks for public safety in such hazardous conditions. At the same time, it is important to ensure that appropriate "ice melt" chemicals are selected to minimize possible environmental effects.
There are more than 100 brands of available products that can melt snow and ice. The ingredients these products use and the degree to which they work, the temperature that you use them in, and their cost varies greatly.
While these melters aid in the prevention of snow and ice build up, some can cause harm to your lawn, your property, or even worse, to your loved ones. It's important to know which product is more environmentally friendly and safe for pets, vegetation, sidewalks and your building.
To melt ice you have to do one of two things: 1) raise the temperature of the ice or 2) lower the freezing point of the water. Now since you've ruled out using heat, you are left with only the option of lowering the freezing point (chemically) to return the water to a liquid state. This method will work fine if it's ok that you don't end up with pure water. Pouring salt on ice will melt it as salt water has a lower melting point than ice. This is why salt is mixed with ice in a home ice cream maker. As the ice melts, it absorbs heat and freezes the ice cream. Road crews used to put salt on bridges, however, salt promotes rust, therefore, other chemical compounds to melt ice (without heat) have been developed.
The various types of ice melting compounds include:
- Rock salt or sodium chloride (NaCl) - draws heat from the environment rather than releasing it and it loses most of its de-icing effectiveness when temperatures are below
-4° C (25° F).
- Magnesium chloride (MgCl2) - is also known as a corrosive agent, but when utilized as a de-icer, other chemical agents are added to reduce and minimize this potential, but the corrosive attributes cannot totally be removed. Another concern is its reaction with aluminum and galvanized steel, metal hardware and electrical conductors.
- Urea (fertilizer) nitrogen (NH2CO NH2) is synthesized from ammonia and carbon dioxide. It is primarily used as a fertilizer. As a de-icer, it has a lower burn potential than potassium chloride. Application rate is 4.5 kg (10 lbs) per 30 sq. metres (100 sq. ft). It melts ice at temperatures as low as -11.5° C (11° F), but works best applied at -4° C to -1° C (25-30° F).
- Calcium chloride (CaCl2) - is a more effective ice melter than urea, but runoff can damage plants and vegetation. Mixing one part calcium chloride to three parts sawdust helps control runoff. Available in flake, pellet, or liquid form and often outperforms other de-icing products especially at lower temperatures. It produces an exothermic reaction, giving off heat as it melts. Calcium chloride also has a greater capacity to attract and retain moisture directly from its surroundings, which enables it to dissolve faster and start the melting process.
- Potassium chloride - is a naturally occurring material that is also used as a fertilizer (muriate of potash) and a food salt substitute. Because of its high salt index and the potential to burn foliage and inhibit rooting, its use is relatively limited.
- Calcium magnesium acetate (CMA) is a relatively new salt-free melting agent made from dolomitic limestone and acetic acid. It causes little damage to concrete or plants and is used as an alternative to salts in environmentally sensitive areas.
- Gravel, sand, sawdust can be applied for traction only, or combined with urea or calcium chloride to help decrease chemical runoff rates (ashes, wood chips and/or cat litter are other options).
This article does not aim to provide a chemistry lesson, but, strangely enough given the time of year, the reason is protect water quality. Mother Nature effectively deals with most recommended salt applications by way of an appreciable diluting effect of these salts due to rainfall etc. Environmental impact from recommended salt sources is typically minimal. However, there are some forms of ice melt that get marketed during icy conditions that can and do have serious environmental implications: traditional lawn and garden fertilizers containing nitrogen (N) and phosphorus (P).
The final point is simple. Do a little research before choosing and applying ice melt materials and make sure the product is not an N- and P-based fertilizer. Regardless of the season, it is always important to protect our water resources.
Source: Canada Realty News