Brining vs. rock salt vs. beet juice: Winter road treatment methods explained

Diedra Laird/
·5 min read

With more winter weather set to hit the Triangle Friday afternoon and evening, North Carolina Department of Transportation workers spent this week preparing the state’s roadways for the storm.

While Thursday’s rainy forecast originally steered NCDOT officials away from applying brine to roads — rain can wash away the solution and render it useless — N.C. Transportation Secretary Eric Boyette said at a Thursday afternoon press conference that the department had changed course and had already applied more than 1 million gallons of brine to roads around the state.

Boyette also said at the press conference that the department had restocked its salt and sand reserves, which will allow workers to treat roads after the storm hits.

So, what is brine? How is it different than rock salt? How quickly should you clean your car after driving on brined roads?

To answer those questions and more (including why one North Carolina town uses beet juice), we’ve compiled information from NCDOT, AAA and news reports.

Here’s what we found.

What is road brine?

Brine is a liquid solution used to pre-treat roadways before winter weather and prevent ice from bonding to the road surface.

NCDOT says the brine it uses is a mixture of water and 23% salt.

Brine is made by loading a hopper with salt and water and agitating, or quickly mixing, the ingredients until the solution is 23% salt. The solution is then pumped into holding tanks and loaded onto trucks to be sprayed on roads.

It’s best to apply brine when road surfaces are dry, so that the solution doesn’t wash away or become diluted. That typically means that crews won’t brine roads if rainy conditions come ahead of snow or ice.

NCDOT sometimes uses a brine solution with 10% calcium.

This brine solution is used to remove snow and ice during and after a winter weather event.

The solution can be used in combination with rock salt when temperatures are low to keep the salt working longer.

The decision to treat roads with brine is typically made by NCDOT officials 24 to 48 hours before a storm hits.

What are the benefits of brine?

NCDOT lists several benefits of using brine when winter weather is forecast.

Brine lowers the freezing temperature of water to about 18 degrees Fahrenheit, meaning the roads must be much colder to have ice bond to their surface.

Brine keeps snow from being compacted by vehicle traffic, which can turn snow into ice.

Brine is more effective and coats roadways better than plain salt or sand.

Brine gives crews more time to prepare and manage roadways, since brining can occur up to 48 hours before a storm.

Brine is cheaper and more cost-efficient than rock salt.

How much does it cost to brine roads?

NCDOT says it costs about $6 to brine one mile of one lane of road.

That means if the department is brining a four-lane road, it would cost roughly $24 per mile.

Rock salt, which the department also uses to treat and manage roadways during snow and ice, costs about $14 per mile per lane to apply.

To treat the same one-mile, four-lane stretch of road with rock salt would cost $56 — more than double the cost of using brine.

According to a NCDOT website, the department budgets $60 million for storm preparation and snow and ice removal each year.

What is rock salt and when is it used?

If rain is in the forecast ahead of snow or ice, transportation officials could opt to not brine roads, as the rain will likely wash the brine away or dilute it before it has time to act.

In these scenarios, crews could instead use rock salt to melt the ice after it begins to fall.

A 2016 News & Observer story outlines the three-step process crews use for treating roads with rock salt:

  1. Apply the salt to the roads.

  2. Give the salt time to soak into the ice and slush.

  3. Come back to the treated areas and plow away the ice.

How does brine affect your vehicle?

Because brine is made with salt, it can cause damage, such as rust, to your vehicle if you don’t wash it off after winter weather passes.

AAA Carolinas recommends reducing the probability of rust damage caused to your car by salt brine by:

Frequently washing your vehicle, paying particular attention to the undercarriage. Washing your vehicle will loosen, dissolve and neutralize road salts. Many drive-thru car washes offer an undercarriage rinse as an option.

Using a high quality wash solution made specifically for vehicles — not a household dish detergent, which could strip the wax from your vehicle.

Repairing any body damage to your car and touching up paint scratches or chips that expose bare metal. Leaving the metal exposed could lead to further rust damage.

When possible, limit driving immediately before, during and after winter storms, especially when salt and de-icing solutions are being applied and are at their highest concentrations.

“A good car wash is inexpensive compared to the possible hundreds or thousands of dollars rust damage could cost you in vehicle repairs down the road,” a 2018 release from AAA Carolinas says.

How else do crews treat roads for ice?

While brine and rock salt are some of the most common ways to treat roads, there are other treatments available.

Road crews might also apply sand after ice falls, which can provide more traction for vehicles as road conditions remain poor.

Reporting from says that road crews in Boone, in western North Carolina, use beet juice to treat roads. The juice is applied in combination with salt brine, allowing the treatment to stay on the roads longer than the normal brine solution, according to the website’s reporting.

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