There seems to be controversy when it comes to conversations about salt and what it can do – or not do -- to asphalt surfaces. So what is the truth? What are the best practices when it comes to keeping your asphalt ice-free during the winter? Let’s take a look at the effect of salt and deicers on your surfaces, and the different products commonly available: their effectiveness and which are safest for pets, vegetation, and children.
Ideally, you should use deicer on your driveway before the snow falls. However, if you haven’t done that and the snow is already on the ground, you can still apply it. Late application doesn’t work as well, and you’ll have to make sure you get the driveway cleared – potentially by a professional depending on the depth of the snow.
Salt isn’t as hard on asphalt surfaces as many people think. Salt doesn’t cause as much damage to asphalt as it does to concrete or gravel surfaces. Owners of professionally installed asphalt shouldn’t worry about pavement damage by salt usage. This is because hot-mix asphalt surfaces are composed of petroleum, stones, and sand. A professional asphalt pavement installation is designed to sustain the harsh freeze and thaw cycles of the winter season. Concrete and gravel surfaces incur severe damage with rock salt, which can lead to pitting and cratering of the pavement surface. As a result, those types of surfaces are less effective at holding up against weather conditions and eventually need to be replaced more often.
Understand that potholes are not the direct result of salt application on your driveway, but rather ice buildup. You should beware of crackling on your asphalt surface and be proactive by sealing before it’s too late. Potholes develop when water penetrates exposed cracks in your asphalt driveway; followed by the freeze-thaw cycles which expand and contract the water as it freezes, developing bigger cracks that transform into potholes. In addition, the constant weight bearing of the asphalt surface from cars and trucks directly affects the weaker paved areas. Staying on top of your snow removal will greatly extend the life of your driveway.
Shovelling or plowing your driveway regularly is the most efficient way to lessen your environmental impact as the amount of salt or other deicers would be much less. There is an assortment of products available to choose from, depending on your needs. The environmental truth of using salt is that runoff water containing salt greatly affects plants, wildlife, and your local waterways.
Rock salt, also known as halite, is a form of sodium chloride (NaCl), the same as table salt. It is a mineral that is found in sedimentary deposits and is often used in water softening and melting snow. Rock salt, also known as unrefined salt or solar salt, is a type of salt that is harvested from the earth. It has not been purified for human consumption like table salt, so it contains minerals like magnesium, potassium, and calcium. It also contains harmful elements like lead and arsenic.
Sodium chloride is inexpensive and helps keep moisture from accumulating on roads and walkways, but it is not an effective deicer at low temperatures [only good down to -9°C (15°F)], damages concrete, poisons the soil, and can kill plants and harm pets.
Calcium chloride works at very low temperatures and isn't as damaging to the soil and vegetation as sodium chloride, though it costs a bit more and may damage concrete. Calcium chloride attracts moisture, so it won't keep surfaces as dry as many other products. On the other hand, attracting moisture can be a good quality since calcium chloride releases heat when it reacts with water, so it can melt snow and ice on contact. All deicers must be in solution (liquid) to start working; calcium chloride can attract its own solvent. Magnesium chloride can do this too, though it isn't used as commonly as a deicer.
Potassium Chloride melts ice slower than other types of products but is the safest to use around pets.
Calcium Magnesium Acetate (CMA) is a combination of lime and acetic acid (found in vinegar). It comes in liquid or solid form, takes less product to work and is more environmentally friendly.
A combination of magnesium and calcium chloride is safer than chloride-type ice melters around pets, plants and people. It works at very low temperatures, but you must use large amounts for effective melting, and it can corrode concrete surfaces.
Propylene glycol-based products (often combined with urea) offer a safe dog option, but propylene glycol damages a cat’s red blood cells if swallowed.
Depending on what your needs are, and how much snow and ice accumulate in your area in a season, will define how you can deal with it. Overall it is best practice to keep your driveway clear of snow and ice through consistent clearing – either by you or a professional snow removal company. The next step is to decide what type of deicer you will use for the surface you have – and other factors such as environmental impacts, children and/ or pets.