Salt-embedded Asphalt Creates Ice-proof Roads

Scientists have developed a new salt-filled asphalt that prevents ice from forming on roads

By Chloe Olewitz December 28, 2015

Asphalt Salt Road — Andres Rodriguez/Flickr

When winter hits the United States and the roads begin to freeze, driving becomes a considerably more dangerous activity. Icy roads make for hazardous driving conditions, and ice collected over a particularly frigid winter can take weeks to clear away. That’s why a team of researchers at Turkey’s Koc University created an asphalt mixture that is embedded with salt, so roads can de-ice themselves. Roads paved with the salt-embedded asphalt should be able to prevent ice from gathering at all.

One of the problems with existing ice removal products is that if they don’t work when first applied to roads, they don’t stick around for very long, since melting snow and passing cars tend to wash them away. To combat endless applications, the Turkish research team designed their new road material to release a de-icing compound incrementally. The asphalt is embedded throughout with de-icer, so that even with heavy traffic over time, each exposed level of asphalt reveals a new layer of the salt solution.

Theoretically, the salt-embedded asphalt will prevent ice from forming in the first place. Regular rock salt has been a common de-icing solution in the past, but it can do damage to the concrete beneath the ice you’re trying to melt. More industrial de-icing solutions often include chemicals that are dangerous to the environment. The Koc University research team used a compound called salt potassium formate instead, since it has been widely approved as an environmentally friendly de-icing solution. The salt potassium formate is embedded in bitumen, a standard component of regular asphalt. The engineered asphalt also includes styrene-butadiene-styrene, a water-repellent polymer that will help prevent ice from forming on the surface.

A possible downside of the ice-proof roads will be the wear and tear to cars and tires. Any salt compound can do corrosive damage to the structural integrity of tires and the underbelly of cars themselves. Although the researchers haven’t released car-tested data, the asphalt has been tested in the lab for longterm durability. The bitumen embedded with salt potassium formate was as sturdy as regular bitumen. In lab trials, the de-icing asphalt released the salt solution for two months. Researchers expect the compound to work for years when applied to real public roads, as car traffic peels away new layers of salted asphalt over time.

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