Salt is unavoidable; whether it’s sprinkled in our food or in mass amounts on the road. You’ve likely run across an icy sidewalk covered in it, or drove on a highway that was recently coated in a salty concoction, only for your car to receive a fresh coat of white “paint”. Deicers like these are staples in the snow & ice industry and help keep the public safe. As all snow contractors know, not all salts are created equal. Some work better than others, not only based on the chemical composition or the brand, but also on what the environmental conditions are like. Let's do a deep dive on the science behind deicers, along with explaining how changing weather conditions affect how they work and what that means for your operation response.
In a nutshell, de-icing products are usually in the form of salts, that help prevent and remove ice & snow build up on surfaces like concrete and asphalt. They are designed to lower the freezing point of water, which in turn affects the freezing properties on pavements, and melting snow or ice present. Usually, these are used either before or after snow/ice has accumulated.
There are certainly benefits to treating surfaces before and after snow or ice has fallen. Pre-treating surfaces are commonly done to help prevent snow or ice from accumulating on surfaces. Even when it does accumulate, the chemical composition of the deicers help prevent a tight bond between the ice and pavement from forming. After the snow or ice has already fallen, these deicers can still be applied to help melt the remaining accumulation. This is especially true in hard freeze-up situations when temperatures drop well below freezing.
While it’s great that salt is able to melt ice, it can’t do it with the help of some moisture! This is especially true for rock salts like sodium chloride, which do a rather poor job of drawing moisture on their own. That's why many deicers are either dissolved in or have water applied to them, creating some brine that helps speed up the deicing properties. Other types of chemicals, like magnesium chlorides, can be turned into a brine but are by themselves much more efficient in drawing moisture from the environment in order to activate deicing properties.
We mentioned that salts are used to not only help prevent the hard bond of snow/ice to a surface, but also to prevent said snow/ice from having a chance to even stick. Think of this like adding butter to a pan when cooking an omelette in the morning. Just like what deicers do to hard surfaces, the butter in our comparison acts as a barrier between the hot pan and the egg, preventing that perminent bond from forming. While there are non-stick frying pans, the same can't be said for sidewalks and roads...
(Just like deicers, butter or oil on a frying pan helps prevent the bonding of food to the surface)
We're not here to list every type of deicer under the sun, but we want to highlight are some popular types used today, along with going over their pros and cons.
Sodium Chloride (NaCl2): Aka Rock Salt
Magnesium/Calcium Chloride (MaCl2/CaCl2)
Potassium Chloride (KCl2)
Agricultural Products (Beet Juice, Corn Syrup, Molasses, etc)
Sand or Grit (Has no deicing properties, but is used for traction)
Alright. We've gone through some types of de-icers, along with the science behind how they work. Now, let's dive into our forte; How weather plays an important role in the effectiveness of salts and brines for snow & ice removal operations. The primary goal for any snow contractor is usually to prevent snow/ice from completely bonding to pavements. Depending on tolerance levels and sensitivity of certain properties/sites, snow is sometimes allowed to accumulate before getting pushed. However, if no salt product is applied before this snow or ice falls, a bond on the pavements is more likely to occur. This ice-pavement bond becomes much harder to completely remove especially if left to sit and even freeze-up as temperatures get colder.
There are many factors that affect when and how you should be using deicers, such as the time of day, the relative humidity/temperature, even the precipitation type. Let's run through some situations:
For situations where precipitation type is not straight snow, it can make pre-treating tricky. This is especially true during changeover events where plain rain is forecast to become sleet or snow. A changover to sleet or an event with mostly sleet, however, is very annoying to handle. Sleet (not to be confused with freezing rain) acts differently than snow, since the ice molecules in sleet are bonded much tighter than snowflakes and do not break down as quickly when in contact with salt or warm pavements. No matter if your surfaces have been treated or not, or even if air temperatures are well above freezing, steady sleet is going to accumulate easily. We talk all about the different properties of snow and sleet here.
Freezing rain is just as annoying to handle. It's a very misleading preciptation type because it does fall as a liquid rain until it comes into contact with a surface that is at or below freezing. At that point it becomes an icy glaze that can catch people off guard, because most associate rain with warm/non-problematic events in the winter time. The issue with treating for freezing rain is dilution of salt. One application for light freezing rain/drizzle may be ok, but if rainfall rates are heavy enough, it can dilute or wash away deicers, leading to more ice and the need for multiple applications.
(Freezing Rain is a sneaky precipitation type. If it's raining below 32 degrees, watch out!)
Timing is also key on how you use deicers...the time of day and year, along with the sun angle, play an important role in how your deicers will work. Pavements act differently based on their composition and their relative placement to direct sunlight. A shaded sidewalk stays colder than one exposed to sunlight, whether or not it has been treated. These tend to cover under snowfall much easier than surfaces exposed to sun...all thanks to pavement temperature differences. Of course, snowfall rates throw a wrench into that logic, because heavy snow rates will evnetually cover almost any type of surface. Snowfall that occurs during the early or late season (October and March) can also be harder to accumulate during the daytime, thanks to the higher sun angle that can heat up pavements much more efficiently than during the middle of winter.
As you can see...weather is so impactful to the type of material you use and how you prepare for a winter storm. We only mentioned a couple of deicers here, but there are a plethora of chemical combinations, brands, and techniques in the market right now that you can use. We're not here to recommendations on what types of deicer to use or how to run your operations. We're meteorologists first and foremost, but we can suggest the type of work you are likely to encounter (deicing vs pushing events) based on the weather. With how dynamic forecasts can be (temperature swings, precipitation changeovers, pavement interactions, etc.), one type of product or method will not solve all issues. Ultimately, it's up to the snow professional to use their best judgment on the types of products and procedures that work and don't work for their business.
When you're planning for a snow event, there will be times when you need some extra advice on salting vs. plowing. Having a better idea of when the snow or ice will arrive, if there are changeovers, as well as how pavements will be affected are crucial factors to determining the best operational strategies for your bussiness.
Luckily, that's where Storm Alert comes in. As weather experts, we have a deep understanding of weather forecasting, with over 35 years of experience in consultation work with snow & ice professionals. Storm Alert goes above and beyond a normal forecast, providing start and end times for precipitation, the range and confidence of snow/ice accumulation, pavement accumulation, winter weather hazards, even our new PavementRisk™ temperature outlook. Storm Alert clients trust our meteorologists to guide them through the storm based on frequent forecasts and real time updates, whether it be via email, app notifications, or even over a phone call! We cut through the hype, bringing you a "fluff-less" decision support tool, tailored for the snow & ice industry.
To learn more about Storm Alert, as well as how you can take advantage of our 24/7 weather monitoring and consultation services, email email@example.com or call us at 908-850-8600 to quickly get in contact with one of our sales team members today. The next time you think Weather, think WeatherWorks!