On winter roads, a de-icing stew of more than just rock salt

On winter roads, a de-icing stew of more than just rock salt
A dump truck is filled with rock salt in New London, Conn., in January. (Sean D. Elliot / The Day)

Friday marks the first day of spring, but tell that to cities still smothered in snow.

Consider Boston, which Sunday set a new record for snow in a single season there — 108.6 inches.


The city famous for tossing tea into the harbor has lately resorted to flinging snow into the sea as well. It has used 114,057 tons of rock salt to melt and clear its icy roads.

Across a snowy nation, rock salt — the go-to product for de-icing roads since the 1950s — has been in such demand that salt mines earlier this year were hardly able to keep up regular supplies.


Cue the ingenious spirit of American invention.

As the snow wears on, scientists and public works directors across the country are looking at a whole new host of products to help make roads safer: Beets. Cheese. Pickles. Vodka.

These products are not intended to be a substitute for the ubiquitous rock salt, but to increase its efficiency, said Xianming Shi, an associate professor of civil and environmental engineering at Washington State University who has researched environmentally sustainable and cost-effective winter road treatments for more than a decade.

"In the last almost 40 years or 50 years, people have been searching for that silver bullet, but that may not exist," he said. "The best we can do at this point is to advance on all fronts."


Last year, municipalities across the country would have welcomed alternatives to rock salt. Heavy snows led to shortages, and many cities depleted their reserves.

The shortages carried over into the beginning of this winter, said Doug House, general manager of municipal services for Moline, Ill., who worked to secure enough salt for state cities as president of the Illinois Public Works Assn.

Rock salt has been used to de-ice roads since at least the 1950s, said Morton Satin, vice president of science and research at the Salt Institute, a nonprofit trade organization that advocates salt use.

Over time, though, concern has grown over rock salt's effects on the environment. Vegetation along highways sometimes turns brown. Steel bridges, concrete pavements and cars corrode. Studies have shown high levels of salt in groundwater, which may be traced back to road salt, Shi said.

"The challenge has been for highway agencies or local road agencies that they really cannot stay away entirely from chlorides, because that's the cheapest solution," Shi said, referring to salt by its technical name, sodium chloride. "In the short run, the focus has been how to use less chloride without sacrificing level of service."

This is where the beets, pickles and cheese come into play. The vodka too.

Researchers have started to look to local waste materials as potential additives to salt mixtures designed to make it easier for ice to melt. None of these ingredients specifically act as de-icers, but they do help weaken the bond between water molecules and decrease the freezing temperature for ice, Shi said.

Lincoln, Neb., went with beet juice.


The dark, slushy liquid once discarded after sugar beet processing is now a commercially sold product that the city mixes with its own salt brine to coat road salt or spray on the streets, said Ty Barger, the public works maintenance manager. The beet juice helps salt stick to the pavement and reduces the amount of bounce and scatter from the granular salt, cutting down on waste and increasing melting capabilities, Barger said.

The city uses a nearby supplier that makes juice from in-state producers for a fairly low price, he said. Ten percent of each gallon of brine is now beet juice. Barger said he expected to go through 25% less salt this year as a result.

The dark brown liquid mixture was first laid down on Lincoln roads in November.

"It's done nothing but good for us," Barger said.

Other states, including Wisconsin, have turned to cheese byproducts.

Cheese-making, like pickle-making, uses water that's usually discarded after use. This salty water can be used as salt brine for the roads, said Mark Devries, an application expert at Vaisala, a Finnish company that makes environmental and industrial measurement products. The company has also started looking for ways to treat road ice.

And then there's vodka, or rather, vodka byproducts. Shi started a research project to look at the leftover barley residue from an Alaskan vodka distillery. The goal was to take the liquid waste and mix it with salt brine and other commercial additives to make something more powerful than typical salt brine, and less damaging to concrete, he said.

"The philosophy is very simple," he said. "Whenever you add stuff to water, then there's a decent chance it will be less likely to freeze, because it's not pure water. If it's pure water, it's relatively easy to freeze."

The research hasn't stopped at chemical additives. One ongoing research project looks at changing the composition of roads on mountain passes or bridges so that ice and snow do not even bond to the surface. Adding more rubber particles to the road mix would make streets less likely to attract water, Shi said.

All these options lead to the same conclusion, he said.

"I think it's really to reduce our environmental footprint of this whole industry," he said. "On the financial side, many states are having a hard time keeping up with the preservation of their infrastructure, and we have this high priority on safety. There needs to be a more balanced approach."

Back in Nebraska, workers in Lincoln made one discovery with their beet concoction this winter. The smell can be a bit musty and unpleasant, so after a month of use, Barger's team revised the recipe, adding a tiny bit of Douglas fir fragrance to the mix.

"Why not make the streets smell like Christmas every time it snows?" Barger said.