When it comes to winter weather safety and clearing those snowy and icy parking lots or driveways, the conversation comes down to one big question: Which is better – ice melt or rock salt? The difference between the two products is in their chemical composition and how they work to melt ice.
Rock Salt is the chemical composition of sodium chloride – literally big chunks of super-powered salt that has a chemical reaction with ice/H2O that creates heat and melts the ice. It lowers the freezing point of water, and one of its benefits is that it provides instant traction on snow and ice.
Ice Melt also contains sodium chloride, but its chemical composition includes magnesium chloride pellets and calcium chloride pellets. Unlike its rock salt counter-point, Ice Melt has the appearance of flakes or fine-grain sand. It, too, is fast-acting and actually works to melt ice faster than rock salt. The biggest difference between the two is that Ice Melt will not create instant traction on snow and ice like Rock Salt will.
Both work to melt ice. One does so a little faster, while the other provides traction while performing its primary function of melting ice. The choice of which product to use really comes down to where it needs to be applied – a parking lot or a main drive versus a set of stairs or a sidewalk – and consideration of side-effects. Most people choosing between the two tend to boil down the comparison to a handful of questions:
Which is more cost-effective?
The average price for Rock Salt in the U.S. is anywhere from $10-to-$15 per 50-pound bag, depending on the part of the country from which you’re purchasing the product. There are some generic brands that can be found for as low as $8 in some places or online, and buying rock salt in bulk (by the ton, for instance) often offers a discount. In some cases, purchasing in bulk lowers the average cost-per-50-pound-bag to as low as $5 or $6.
Ice Melt, by comparison, comes at a higher cost. Starting price for a 50-pound bag of Ice Melt is around $13 on the low end and can be as high as $25 in some parts of the country. Many companies offer 40-pound bags instead of 50-pound bags, like their Rock Salt counterparts, to help offset the cost – but in the end, it’s less product for the same price. Buying in bulk does not equalize that cost comparison, either, as purchasing by the ton only lowers the cost-per-50-pound-bag to about $9 or $10.
Will salt damage my concrete parking lot?
Cost isn’t the only thing to consider when choosing between Rock Salt and Ice Melt. The wear-and-tear on the parking lot or drive on which you’re applying the product is also something to consider. One of the positives of Rock Salt is that it provides traction while working to melt the ice – but the side-effect is that those chunks of rock can sometimes grind against the surface and chew up the pavement/concrete. Over time this can damage a parking lot or drive, but that’s not typical with appropriate application. Rock Salt works by interacting with ice and creating a slush-type solution that drains off of the surface or can be easily plowed away. If applying the right amount of product, then the rough interaction with the surface is negligible and shouldn’t affect the parking lot much, if at all. Various Department of Transportation studies indicate that a light-icing situation requires only 200-to-250-pounds of Rock Salt per acre to reduce a light accumulation of ice. Under those conditions, the melting process will take approximately 45-to-60 minutes.
A common myth about Ice Melt is that because of its chemical composition it is bad for asphalt. This is not actually true, and studies have shown that Ice Melt has little-to-no effect on asphalt. It does, however, have a long-term effect on concrete – which is a material that is notoriously sensitive to various forms of chemicals. Ice Melt certainly works more quickly than Rock Salt, but it can absolutely wreak havoc on concrete. One bonus of the magnesium chloride product, however, is that it works better with concrete surfaces and has been proven to be less damaging over time. This is, of course, the highest-cost option, however, when it comes to de-icing products.
Which one is safer for my employee’s vehicles?
While Rock Salt is great for providing traction on those slippery roads while it works to melt the ice, it’s also messy. Anyone who lives in a wintry part of the country is used to seeing cars with dusty salt stains along the sides and around the tire wells – and don’t even think about looking at the undercarriage! Rock Salt is, unfortunately, extremely corrosive and over time can cause extensive damage to vehicles. This shouldn’t be a concern if the cars in your parking lot would be interacting with the product only a couple of times per year, but if you live in a part of the country that requires frequent de-icing then this definitely should be a consideration. The more Rock Salt a car interacts with, more that the car will need a thorough wash to avoid corrosion. According to one AAA survey in 2016, U.S. drivers paid an estimated $15.4 billion in rust repairs caused by de-icing methods over the previous five years – or $3 billion annually.
Ice Melt, by comparison, has less of a corrosive effect on cars. Over time it, too, can damage a car, but the effects are far less extreme and happen more slowly. If used frequently, it still would require car washing more often than not, but the effects are less than the Rock Salt counterpart.
Which one won’t kill my landscaping? Which one is more eco-friendly?
Anyone who has walked out to a browning lawn in the spring following a rough winter can tell you first-hand that Rock Salt and Ice Melt can have damaging effects on those well-manicured lawns and landscapes. Both types of products can hurt your landscaping, but there are varieties of these products that offer eco-friendly options.
The common, low-cost Rock Salt that most city governments and contractors will use tends to be the most damaging product to a lawn/yard. The more that product gets used in your area, the more you can count on a brown lawn. But on the plus side it’ll kill all your weeds!
The next-step-up Rock Salt – which uses a CaCL2 chemical mixture – will be better for your lawn, but tends to have more negative effects on concrete patios, pavers and walkways. This product is typically best-used for temperatures below 0-degrees Fahrenheit.
The Ice Melt solution that utilizes magnesium chloride has been proven not to damage lawns, though it is the more expensive of the de-icing products on the market. Pet owners concerned with how this type of product can potentially harm their pets can also find 100% organic, all-natural, salt-free options out there that are eco-friendly and are great to use around pets. These products work similarly to ice melt and will work quickly to melt ice, though won’t provide traction like Rock Salt will.
Which one works the quickest?
Almost universally Ice Melt works more quickly than Rock Salt. There’s about a 20-degree Fahrenheit difference between the melting points of Rock Salt and Ice Melt – from 5-degrees above zero for Rock Salt to negative-15-degrees for Ice Melt. The latter does not provide traction while melting the ice, however, and the slush that is formed during the melting process must be plowed away within the hour so as to avoid re-freezing that would require re-application of the de-icing product.
Are there other, lesser-known alternatives to salt?
There are some out there who swear by Kitty Litter as an alternative to Rock Salt or Ice Melt. It’s a home remedy, for sure, but it doesn’t actually melt the ice. At best it works as traction on those slippery surfaces. The better options out there are organic, salt-free de-icers that melt ice and snow while also providing a measure of traction. These products are, of course, more expensive. But when it comes to actually melting ice, there’s really no substitution for Rock Salt or Ice Melt. You can use other non-chemical products to create traction or mitigate the level of danger associated with ice and snow – such as heated driveways or using sand or sawdust – but those methods are far less effective and create a measure of pollution that requires clean-up afterward.