Every winter, millions of tons of rock salt is sprinkled across roads in the US, mostly in the Midwest and Northeast regions. It’s a cheap and effective way to prevent accidents. Rock salt is chemically the same as the stuff that sits next to the pepper, except it isn’t as finely ground, and it doesn’t have sodium or potassium iodine added to it to prevent goiters. Both table salt and rock salt melt ice by lowering the freezing point of water. So does sugar.
Much of what we salt the Earth with every winter comes from underground networks of salt crystal that formed when various ancient seas dried up. As natural as it may be, rock salt is bad for the environment. For one thing, chloride is forever, and can’t easily be decoupled from the soil and water it taints when it washes away. Rock salt also corrodes concrete, makes its way into the groundwater, and is bad for pets. Worst of all, its efficacy drops along with the temperature. At 15° F (-9° C), rock salt loses more than 86% of its melting power.
All this salt is not great for cars, either — it’s bad for the paint and eats up the frame. In the saltiest parts of the US, aka The Salt Belt, cars only last a handful of years before they become Flintstones mobiles. Well, not really, but salt is terrible for the brake lines and most of the undercarriage. Consumer woes aside, there’s a real environmental impact to manufacturing all these disposable cars to meet the demand.
But the problem is that we need to use salt, or at something like it. Even though millions of people are staying home a whole lot more, the trucking industry still relies on salted highways and local roads. So if you like stocked grocery stores and stuff arriving from the Bezos Barn in a timely fashion, you can see the problem. So what are the alternatives? Are there any?
Freezing point depressants aren’t the only solution, but they’re usually a large part of it. For years, plenty of jurisdictions supplemented salt with sand until it started clogging the sewer pipes. One of the modern alternatives to salting the streets willy-nilly is to meter out usage based on road temperature readings. Another trick is to distribute a liquid salt solution instead, which works faster and won’t bounce into the gutter.
As far as eco-friendly alternatives go, some individuals use abrasives on their sidewalks and driveways like kitty litter, coffee grounds, or chicken grit, which is a mixture of shells and small pebbles that helps their digestion. But of course, all of these are just traction agents — they don’t melt the ice. Although when it comes to your property, unless there’s a layer of ice under the snow, some kind of traction agent will probably suffice after shoveling or snow-blowing.
Of course, these would likely cause the same problems as sand if used on a large enough scale, especially coffee grounds. So even though these may be better for the environment, they come with their own set of problems.
Brine is Fine, Sort Of
Several years ago, we heard that Wisconsin was using cheese brine on their roads, and not only is it true, it works at much lower temperatures than salt. But how does the average Joe source his cheese brine for home use? We’re not sure. Fortunately, other food by-products work too, like sugar beet juice and pickle juice.
But some of those have their problems, too. Sugar beet juice still requires salt to work — the point is to make a goo that won’t run off into the gutters as readily. The problem is that the organic material can deplete the oxygen in rivers, lakes, and streams.
Possibly the worst brine of all comes from fracking, an already controversial practice. This radioactive runoff has already been used in places like Pennsylvania. Road salt is starting to look pretty good, no?
Is There a Nicer De-Icer?
But there is one that’s sort of better than salt: potassium acetate. It contains no chloride and is biodegradable, but it has that oxygen-lowering problem and has been proven harmful to aquatic insects. Potassium acetate is more effective as a preventive measure, as it keeps ice from bonding to surfaces. It’s roughly three times as expensive as rock salt, but a little goes a long way, so the cost is nearly even. Another preventive treatment known as calcium magnesium acetate is environmentally friendly, but it’s only as effective as rock salt when the temperature plummets.
So, what’s the answer? We suppose change begins at home, so consider the contents when you go to buy de-icer, or try making your own. Whatever you do, do it sparingly.
[Main and thumbnail images via Shawn Dearn on Unsplash]
79 thoughts on “The Road Is Peppered With Rock Salt Alternatives”
Solution: studded tires, learning to drive, and this:
May work where there is a constant cover of packed snow on the roads, not where the snow melts and the studs will just obliterate the asphalt roads, which is pretty much everywhere in the US, except maybe Alaska.
In Sweden we forbid the use of studded tiers outside of the winter season. (as to greatly reduce road wear.)
Though, we also require the use of winter tiers during winter, and there is “all around tiers” too, but they kind of get worn down quite fast.
In the end, almost everyone here changes their wheels twice a year.
In regards to removing ice from the roads, we mostly don’t.
Just put down a bit of gravel, that then gets swept up during spring and reused the next winter. It is quite simple and effective.
Why put down tons of salt that just ends up washing into the fields and the like, that already have issues with too much salt accumulation. Not to mention rusts way the cars and likely increases the amount of mechanical failures and accidents resulting from such.
Up here in Montana we use gravel as well. We don’t require stubbed tires, but most people do switch over to some sort of winter tire.
As for tire laws we are exacly like you in Quebec, Canada.
We mandate winter tires, we allow studded tires only in winter.
I just don’t remember what mix we usualy use. It changed a couple of time and may be city based.
Even in places like Sweden, the more popular roads stay clear and dry most of the winter simply by people driving on them. There’s long transition periods in the fall and spring when it’s freezing cold but not enough snow to make a permanent layer of ice, and people drive on studded tires, and it isn’t actually such a big problem. It doesn’t “obliterate” the road unless your asphalt is made of cheese.
It is not that the asphalt is made of cheese, but at least here in Massachusetts we have rainy season in spring, and heavy downpours during the summer. So roads are covered with asphalt that is more porous to help drain the water as fast as possible.
Different states have different asphalt needs depending on their local weather. There are vast lengths of highways towards that south that are made of concrete slabs. Works for their weather. Not ours.
Alaska on the other hand had a lot more snow/ice for longer of periods of time during the year, so they use different types of pavement too.
In Massachusetts, we simply do not get enough ice/snow to justify studded tires. They do encourage winter tires but they are not mandatory because the roads are cleared up pretty quickly during the storms.
Here, salt is really only used if the weather forecast shows the possibility of freezing rain, black ice and snow fall with or followed by showers that are then followed by a dip in temperature that leads to the roads freezing.
There are a few places in the use, that unless you are using winter tires AND you have chains set up on them, you are not allowed to drive on that road and they will make you turn around and take the long way around.
So as you can see, different places have different needs based on their weather patterns and traffic situations.
Man, why haven’t they thought of that?!
Learning to drive… yes and no. Yes of course and that means really understanding inertia and friction. But in the mid-Southeast US we catch a lot of flak from Northerners for not knowing how to drive on snow (rightly so for many), yet we’re not much worse than they are on ice, which is what we usually get. But it’s only a few days a year. Just stay home if you can.
At our home, we just use plain o’ sand through the winter. No de-icers. We did use some in the past, but not worth it. Big deal is to prevent slipping while walking. Sand does the trick.
Funny some places far colder than the USA get along fine without salting. We underdtand that the speed limit is the upper, not lower, bound.
The issue with not salting at all is that ice builds up and packs into a lumpy groovy mess that breaks your wheels. You then have to level it mechanically, which means scraping the surface all the way down to the blacktop, which destroys the asphalt. A gentler method is to break the ice with a pinwheel first and scoop it off, but all mechanical means of ice removal hurt the road surface.
I don’t know about it ‘breaking wheels’ as that hasn’t happened here in MT. Our side streets all get ‘groovy’ and bumpy in the winter. You just drive a bit more careful. Spring it goes away…. Nature takes care of itself.
Most residents don’t like the salt substitute they put on our highways and main roads… But ‘government’ says it is a ‘safety’ issue …. so have to put up with it :( . How we did without it many years ago now and still lived through the winter is a ‘wonder’….
I’ve run a flat by driving into an ice pothole.
Potholes are a pre-existing condition of the road. Generally ice expands it during winter, but they are worst at spring once ice melt. Salt won’t solve that issue.
I wasn’t talking about holes in the road itself, I was talking about holes in the ice cover.
“The issue with not salting at all is that ice builds up and packs into a lumpy groovy mess that breaks your wheels.”
Wat? I’ve seen some broken wheels from heaves in the road from weather changes, but I don’t think I’ve seen broken wheels from packed ice.
If the road isn’t properly plowed frequently enough, first thing that happens is the heavier vehicles wear two grooves into the ice and all the other cars drop into that like railroad tracks. It can be difficult to make any turns because you’re wheel-locked in there. For smaller cars it’s especially annoying because they have narrower track, so you go one wheel in the groove and the other on top, and at some point you slip in the other way.
Then you get ice potholes where there’s manholes and drains. Any liquid water quickly eats a hole in the ice and if you drive into one at speed, it can bend your suspension links or pop the sidewall off the rim and then you get a flat tire.
This is a problem because a day of heavy snowfall can add inches of packed ice on the road as the cars go by, and if it’s never shaved off and leveled over the winter, the heaves and dips can grow a foot deep. Salting it helps by turning the surface of the ice into slush, so you don’t need such heavy equipment to remove it and you can plow more roads quicker, which means lower cost and faster response. If you don’t salt it, you have to keep plows on the call and drive the snow off as soon as it falls down to prevent it getting packed up like that. Once it’s already ice, it’s too late and mechanical removal becomes much slower and damaging to the road surface.
Far colder areas have persistent packed snow at a temperature that does not allow it to be wet or easily melt and then form an ice sheet. In addition the condition is far more uniform, unlike where I live where slightly elevated roads will remain wet and valleys where colder air has settled will be ice covered – not big valleys – just a 30-50 foot change in elevation is enough. So sure, everyone gets along with conditions that last for weeks or months, not so much in areas where the condition might be for a couple of hours every other year.
in North Carolina in the US there might be 1 or maybe 2 substantial snowfalls per year, and the most recent one was rain-to-snow, meaning pre-brining got washed off, and there’s not time nor manpower to refit the thousands of semitrailers with studs that’ll wreck clean road surfaces for one long weekend of ice that’s going to melt in 3 days. But the trucks can’t stop working for those three days, so it’s scrape-and-salt (go look up letsdig18 over on youtube)
More like, funny how most places outside of the US don’t have a clue how it is the US.
Many of us outside of the US have been there, looked around, and decided that’s not how things should be done, especially the infrastructure.
Except the power-flush toilets, those are awesome.
To be fair.
The way snow piles up on the ground, and how the ground changes temperature throughout the seasons isn’t majorly different.
If the weather is hovering around 1-4 C for a week and then suddenly there is 3 inches of snow falling during one night, then that snow will just melt by the afternoon (unless it keeps on snowing), it doesn’t matter where in the world one is. If the ground is “warm”, the snow won’t persist.
Secondly, the watery slush won’t really be a major deficit to the grip of a vehicle, it is similar to driving through a puddle of water, and should be treated the same way, so don’t go speeding through the slush. (Though, most drivers inexperienced with snow don’t know that. Just like most drivers in warmer climates don’t know that even at 4 degrees C one has already lost a fair bit of grip due to the hardening of the rubber in the tiers, ice isn’t needed for a car to loose grip before one expects it to.)
And salting roads is fairly ineffective, especially from a cost perspective. (Not to mention the environmental impact and the corrosion of the mechanical linkages of the cars.)
Where I live we use gravel instead, it stays in place when it rains, it doesn’t really silt up drains, and it can be swept up for the next season. Also, if new snow falls on top, it is still there providing a grippy foundation, and if the snow compacts and freezes then it is suddenly the equivalent of a sand paper, so the ice can stay.
In the end.
The US isn’t the only place in the world that has weird winter practices.
A lot of warmer climates faced with snow have frankly laughable practices in handling it.
“And salting roads is fairly ineffective, especially from a cost perspective.”
Says who? Salt is more cost effective than sand, and is more effective per unit weight than sand (source: https://www.claimsjournal.com/news/midwest/2018/01/26/282727.htm )
“If the weather is hovering around 1-4 C for a week and then suddenly there is 3 inches of snow falling during one night, then that snow will just melt by the afternoon”
For most of the rust belt, we are below freezing from roughly the end of November to the beginning of March. We often have week long bouts where the temperature only rises above 0F for a couple hours total. It was -28C on my drive in to work this morning. Snow does not melt by itself around here.
> it is similar to driving through a puddle of water
Well… until you try to brake, which is when it packs up into the wheels completely unlike water and doesn’t drain off, making you become a sled at far far slower speeds than driving through a puddle. If you want to go around on summer tires, you’re pretty much going <10 mph anywhere.
Still people try, literally up to the point when they can't get out of the driveway for a lack of traction.
>Where I live we use gravel instead
Last time it was icing over, they put gravel on the sidewalks. In the morning it was just sitting there on top of the hard ice like ball bearings. Punctured my bicycle tire and my knee.
Walnut shells in the rubber.
The bigger problem in certain areas of the country, like Massachusetts where I am, snow may very well melt. The problem being snow storms were the snow does start to melt but is followed by a big dip in temperature that ends up in slippery ice. Leaving that around is not really an option when the following morning roads are going to be full of people driving to work on the slippery highways.
In quite a few municipalities, secondary roads are not even cleaned at all.
*looks outside at -30C temperature gauge*
Man, I thought I was silly for living here, where the heck is colder than here??!
The problem that we are trying to solve is traction not trying to melt the ice.
>The process of making and spreading the wood chips, which are coated with magnesium chloride — allowing the chips to better adhere to snow and ice — was brought to Rosemere from Switzerland by the town’s public works manager who thought the process something worth trying, says Westram.
>The wood chips disappear on their own, and can also help vehicles maintain their traction in -30-degree temperatures. Road salt, by comparison, loses its effectiveness at -15.
When the ice melts, the chips floats to the surface (vs grit sinking to the bottom). When/if it freezes again, it’ll be there to do the work.
BTW My first year chemistry prof suggested urea. :P
Potassium formate is one alternative – it breaks down into CO2 and water on its own, and it works down to -58 C, but it’s mad expensive.
It’s less corrosive than salts, but it is slightly corrosive to aluminum which isn’t affected by road salt, so it’s not normally protected against.
Aluminum isn’t affected by road salt? I’ve seen plenty of vehicles with various aluminum panels with plenty of corrosion on them up here in MA.
Not significantly with calcium or sodium salts.
Not true when you combine aluminum and steel, as in aluminum body and steel body panels. Add anything corrosive like any form of salt and the aluminum + steel + salt become a battery with aluminum being the anode, and the anode corrodes away.
But it’s still not as bad as steel which needs no other metal to corrode.
If the relatively lightweight wood chips float, aren’t they just going to wash away to the sides of the road?
Where I live, we just use gravel. It mostly stays in place.
If the ice melts, there is drains to handle that outflow of water, so if the water freezes again, the gravel is still technically on top. But the occasional additional layer of gravel is added when needed.
During spring, it is all just swept up and used for the next season. Typically stored in collection piles near to where it will be used. So if one ever visits Sweden and finds a random pile/mound of gravel in a neighborhood, then now you know what it is for, it’s for winter.
Though, pushing the excessive amounts of snow to the side is also done, it won’t all compact down.
In the end, it is a simple cost effective system that just works.
It doesn’t put tons of salt out into already over salted fields, lakes and such, and it doesn’t end up corroding the undercarriage of cars, and it doesn’t eat away concrete and other infrastructure.
Downside with gravel is that it does generate a small amount of silt, so unsilting the drains is an annual thing. (though, the drains here are designed with this in mind.)
That was my thought too. You can see how salt and sand are cast off to the sides of the road as traffic moves across it, and I’d think woodchips wouldn’t last long in the lane. Maybe if they are soaked really really good and their density increases a lot?
If the snow completely melt, then yes they’ll get washed up. With no slushy snow, you’ll have no refreeze and no nasty traction problems. That’s not when it helps.
Most cases I have seen here is that the snow is not completely removed and a warm day partially melted, followed by a very cold night/day. The water refreeze into very slippery ice and now you have no traction.
This is case with a very big snow storm that usually take days for the snow to be removed. Deep in winter, the weather is not warm enough for the snow to be completely melted or sublimated. The crossing of warm/cold front brings about the snow, melting and refreezing.
I came to mention urea as well. Was a high school science question (compare the properties of these common chemicals, choose one to replace road salt and why).
Right now though there’s a urea shortage and it’s used in diesel exhaust system as well now. So doubt it’s going on the roads anytime soon. Plus there’s probably something negative about the elevated nitrogen in the water promoting algae growth or something
Calcium chloride works best and you can even use it to make beer in the Spring
I live in illinois usa right in the middle of the rust belt. Buy the cheapest car you can find, drive it for 10-15 years, recycle it. Wash rinse repeat. When you first get the car spray the frame/underbody with Fluidfilm. Repeat treatments every other year. Car will last longer and you will not get flintstones holes through floorboard.
All over the Midwest there are broken wagon wheels besides driveways. That’s because nobody EVER set out for Oklahoma, it’s just where they broke down.
Para: An old Gallagher bit.
Nah, I like the cold. Well, I’d move out of Illinois if I was there, but Wisconsin ain’t bad.
If the solution to every problem was move, then we all would be living out of RVs.
Mayhem, You are lucky in Illinois. Your cars last 10 – 15 years. Cars in the real rust belt – in Western NY State next to Lake Erie – last 5 – 10 years.
Funny, I was being told cars have a protective layer on them against salt, and the only time they will rust if that layer is scratched away… by rocks.
They used to put tar on the bottom of cars just like wooden boats. Some still do.
Go to a dealer and looks at rusty frames on brand new trucks sometime.
the ones where the manufacturer cares are galvanicaly coated in zinc
That’s partly true for modern cars. The steel panels used in today’s cars have a protective zinc coating that slows down corrosion. But just like the zinc coating on a chain link fence, once that layer corrodes away the steel rusts fast.
And then there are scratches like you mentioned, and chips, and seams, and spot weld points that all start rust early. And then there’s the stupid Engineering decisions made to save $0.50 like un-plated or poorly plated bracketing.
If you think sodium chloride is bad, look at calcium chloride. When doing high temp corrosion tests on electronic parts, we used CaCl if we really wanted the part to fail. I worked at a CaCl plant in Arkansas and have first-hand knowledge of what that stuff can do. It’s sold both as a liquid shipped in glass-lined rail cars and as flakes in supersacks or bags suitable for the home improvement crowd.
I have a steep cement driveway. Have been using shoveling to minimize buildup, and a thin layer of ash from campfires (firewood, no lumber with nails) for traction on any ice that does form. Working well so far. Just have to be careful not to track it in.
To be fair, around here were I live, most people can get by with just cleaning like you do and spreading some sand over it that can then be swept up to the sides or collected in a barrel to be reused next season. As a home owner, I do say that it is much easier to throw some salt down if I know the drive will get icy, only because if the mailman slips and fall I’m liable for it. Where it not for that type of liability, I don’t think i’d even bother cleaning the driveway, I would just keep on driving over it (but I do have a fairly level driveway).
I only salt our sidewalk in front of our house. Very little on the driveway. The driveway does get strips of ice on it from car tires compacting down any snow fall. So the only way to prevent that layer from spreading, getting larger is to remove teh snow as SOON as it comes down. Whether its 1/2 in. or 3 in. Get that stuff off the surface ASAP. As for surface roads, locally, salting is a a tradition. We live about 20 miles north of a huge salt mine. It’s cheap it’s plentiful, and it’s a tradition. And all our waterways suffer for it, people KNOW it’s bad, and here we are still addicted to salt.
The linked article on radioactivity is terrible journalism — no reference at all to how much gets into drinking water and how close that is to safety standards,
One good point in the article: it points out that Pittsburg draws its water from the river, which is championship level stupidity.
Care to elaborate? Is the river there super polluted?
I live in Switzerland and a lot of our rivers are at or super close to drinking-water-levels.
I find the puns and word choice in this article absolutely delightful.
It is best to put rock salt on rock salt. Pointless, but the best option.
Ha! I knew it! I recognize my city.
(And was just searching for non-salt options for my typical Montreal staircase…)
I’ve seen beet juice and pickle juice used in the northeast USA instead of salt.
I lived in Japan for 3 years, and noticed they usually put down ash on roads, not salt. Sapporo, where I lived for a couple of those years, had a permafrost layer practically of 3 to 6 in of solid hard pack on all sidewalks at all times and everyone adapted by putting rubber studded stretch grippers on their shoes when they went out to walk.
Nearby hotsprings towns like Noboribetsu & Jozankei used hot water from the hot springs in town and routed I believe the runoff underneath the streets and sidewalks effectively like a heated driveway but for an entire town- I never remember seeing them use a plow truck in winter.
I live in PA, we regularly are at the mercy of snow- I have often wondered if there is a practical solution to simply heating all the roads just a degree above freezing- an electric heater grid perhaps powered partially by the traffic itself creating fiction on the road. Some sort of piezoelectric actuated heater system? Is there any practical way to heat the roads to keep ice from forming or the need for salt or plow trucks? Serious question yeah what would it take?
There’s little point stopping just above freezing: turning ice at -1C to water at 1C uses about as much energy as heating the 1C water to 80C.
Phase transitions are energetically expensive. That’s why we use shovels and plows: the energy cost of moving snow a few feet is far lower than the cost of melting it.
Heat the roads. Have a large pipe buried 5m under the road, filled with water, and circulation tubes to bring that water near the surface under the road. In summer, the water captures heat from the road into the underground store. In winter, the reverse.
Popular Science had an article about that. As you can imagine cost would be a big issue.
Where district heating in a combined heat power plant is used, the return pipe is often buried under some major roadway to make use of the heat loss.
The city of Holland, Michigan does that. All the roads and sidewalks downtown are heated by waste heat from the BPW power plant, which is natural-gas fired. (I just had to look it up because I always thought it was a nuke plant, but wanted to be sure. Nope! Natgas!)
It works because Holland is a tiny town and it can get a lot of bang for the watt. I don’t think that system makes sense over large areas, especially as generation shifts to less-thermally-wasteful means. But if we’re still gonna have steam cycles somewhere, yeah, snowmelt systems are a great dump load in the winter.
The irony of “less thermally wasteful” means of generation is that 60-80% of the overall energy demand is still going towards heating. You’re just making it out of more expensive sources.
For plain thermal power, unless you have to import it from far away, coal or gas is just 1-2 cents per kWh at the system level and 5-6 cents retail, versus electricity at 10-20 cents. Even if it’s less efficient in direct terms, it makes sense to burn stuff for heat simply for the low price – because money is economic activity and economic activity uses energy. In other words, to pay for the “more efficient” means of generating energy, you use more energy, which means it becomes less efficient in real terms.
My civil engineering job only exists because of damage done to steel reinforcing in concrete by chloride.
So I am a big fan of rock salt 🧂👍
They have a pilot program outside of Munich where they use pickle brine. Which I guess has a lot of salt in it, so maybe that’s not so cool. But the idea that the roads would smell all vinegary-garlicky-dilly is pretty appealing to me…
“Another trick is to distribute a liquid salt solution instead, which works faster and won’t bounce into the gutter.”
No, it just runs into the gutter with the snowmelt and rain instead. Seriously, where do you think it goes?
I think we use different kinds of salt here in the Netherlands, depending on the roads.
In towns and villages rain water from roads is collected by the sewage system (and often in different pipes from house-waste water) while for example highway’s do not have a gutter system.
I do not know any details though.
Some municipalities around here (Northern IL) have been using a product called Magic Minus 0 for 10 years or so. It’s a liquid made of magnesium chloride and molasses. Either use it straight or coat your road salt with it. As a liquid it is often used as a pretreatment of the road surface when there’s a snow or ice storm imminent. The claim is that it is less corrosive, biodegradeable and effective to a lower temp.
I imagine that could have other consequences involving accidents with wildlife though. Also, Boston put molasses on the road once before, it didn’t end well.
In Colorado they use a liquid solution of magnesium chloride on the major roads. It’s claimed to be less corrosive to vehicles and better for the waterways. You still plenty of rusty vehicles and dead trees… but maybe it would be worse if they used plain old salt.
How about solar roadways?
If you first clear them, then they you can use their low efficiency to heat up the road.
Western NY State did far worse than salt, and as far as I know they still do. They spread cinders, the waste product from power stations, on the roadways and cinders contain something far more corrosive than salt – sulfuric acid. In the 1970’s any good car would last 5 years, a Ford would last three.
I used to see a liquid product advertised in magazines. It was called Bare Ground and was to be applied to concrete and asphalt sidewalks and driveways and allowed to dry before snow fell. Would be nice to be able to pre-treat to melt snow.
The stuff was stupid expensive for a gallon so I never bought any but have wondered what it was.
It’s still around, it’s magnesium chloride.
I have family in Vermont. Used to be, my uncle would fly south for family get-togethers, and buy a beat up used car to drive home. A cheap used car from Virginia would only last a few years in the Vermont salt, but I guess it worked as a second car, or one for his kids.
Smart. It’s just a cost of living there, and cheaper than killing your nice car.
Please be kind and respectful to help make the comments section excellent. (Comment Policy)