To treat icy roads, highway agencies look to grapes, cheese, and vodka as alternatives to salt
Road salt works, but it also corrodes. Would roads and cars be better off with less of it? Inside the quest for alternatives.
Various studies have affirmed that red wine can benefit the circulatory system, thanks to the antioxidants in the grapes. Now a group of researchers has concluded that grapes might do wonders for the nation’s traffic arteries in winter and put them on a lower-salt diet.
In two years of laboratory testing, a deicing compound with a grape extract outperformed standard salt-brine solutions and others that use the increasingly popular beet juice — which New Jersey uses when it’s especially cold — the group reported in a paper published in the December issue of the Journal of Materials in Civil Engineering.
While "not a silver bullet,” said study coauthor Xianming Shi, a professor of civil and environmental engineering and a national expert in winter road treatments. “It’s one step.”
That would be one step toward . curbing salt use. Salt is tough on roads, not to mention vehicle undercarriages, and a threat to groundwater, so road departments and researchers have been looking for alternatives — and finding some unusual ones.
Salt use has long been controversial. In the mid-19th century, New Yorkers complained that it ruined the streets for sleigh traffic.
It remains on the road-treatment table, however, because it is relatively inexpensive, although costs have been rising; plentiful; and it works.
» READ MORE: Road salt levels in some Philadelphia-area streams hit toxic levels
Traditionally, it has been used as deicer, designed to melt ice and snow. But an anti-icing movement has gained traction in the last 15 years, with more highway departments pretreating roads with a liquid/salt brine well before anything frozen falls from the skies.
The brine typically is a mix of water and plain old salt, with splashes of magnesium chloride in some cases.
The concept of concocting an ice-melting slurry has paved the way for experimentation with unlikely snow-fighting ingredients as researchers look for other options to keep roads, and the environment, as safe as possible.
PennDot has considered a variety of additives, and commissioned a study by Temple University researchers. The agency’s conclusion? Salt is “the most affordable and effective solution for winter highway maintenance,” said spokesperson Alexis Campbell.
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Pennsylvania’s and other highway departments are being shortsighted, counters Shi. He coauthored a separate study that said salt use causes $5 billion in road and collateral damage annually.
“By buying the more expensive product you save money in the long run,” he argues. “The hidden costs are not fully integrated into that decision-making."
Road departments would be better off going “green” by mining agricultural products from local sources that could not only serve as salt substitutes in the brine formulas but could make them more effective, ultimately reducing the need for salt on roads.
He gained a measure of celebrity five years ago while doing research for Alaska, where it does tend to get cold, by cooking up an effective ice-melt recipe that included leftover barley residue from vodka distilleries.
Polk County, Wis. — where it got down to 17 below zero on Wednesday morning — had substantial economic and salt-saving success for more than a decade with salt from cheese rinds, said county highway department chief Emil “Moe” Norby.
So just how might these alternatives work, and are they any better than plain rock salt?
The brine before the storm
When snow is in the forecast, the telltale signs of brine are appearing ever-more frequently on the roads in the form of what looks like plow (think agriculture, not snow) rows.
Usually that brine is a little less than one-quarter salt, or about eight times saltier than the average ocean.
Sparing our readers the physics, salt works by lowering the freezing temperature of water. Brine is preemptive.
It is still salt, with attendant harmful collateral effects, but it keeps snow and ice from bonding on the road surface; it tends to stay put, instead of bouncing around; and it can be a low-grade epoxy for the subsequent showers of salt crystals.
Laboratory studies have determined that various additives, such as Shi’s milled Concord-grape waste powder, could reduce the use of salt and lower the temperature at which snow and ice would freeze, and be gentler to the environment.
Using a recipe that was just under 1% of grape extract reduced the freezing temperature to 11 below, his team found
Norby, despite not wanting to indulge in upmanship, said his cheese variant could go even lower.
Looking for a way to cut back on salt and sand, Norby came up with the idea of experimenting with the salt brine that was a local dairy’s waste product.
He visited the plant and took home two 12-ounce containers of the brine and was sold on the concept after it survived two consecutive nights of low temperatures of 21 below.
The state environmental department signed off on the agreement, and the solution was strained and pumped into trucks and delivered to his plant. All his crews had to do was filter the mixture to remove any solid whey products.
» READ MORE: Where will all that road salt go? Into the Delaware River — and that's a concern
He said the results were astounding, and he was able to cut back salt expenditures by 30%. And, no, it did not leave a cheese odor.
Unfortunately, the county is not using it this winter: The dairy was bought by a bigger outfit that closed the plant during the summer.
A public works in progress
That state of winter-road treatments has been ever-evolving.
“It’s part art, it’s part science,” says David Hunt, communications director for the Wisconsin highway department.
New Jersey has found that a recipe that includes sugar-beet juice not only lowers the freezing temperature but its stickiness helps paved surfaces retain salt, said Transportation Department spokesperson Steve Schapiro.
No one has yet found that “silver bullet,” department officials say, and what’s more, winter storms are idiosyncratic.
» READ MORE: Snow falls in Philly area in advance of wintry mix that could affect afternoon commute
“There is no single and ready-made ‘best’ method for all circumstances,” Shi and his associate wrote in that 2014 paper.
For example, plain salt isn’t effective when the temperature drops below 15 degrees. Freezing rain and sleet present different challenges from snow. Brine is a waste when a storm starts as rain.
And while the alternatives might show promise, highway-treatment experts agree that salt will remain a significant part of roadbed diets for the foreseeable future.