Research shows road chemical damages street health

Chloride causes unseen negative consequences for city infrastructure



Xianming Shi, associate professor for the School of Civil and Environmental Engineering, discusses the use of magnesium chloride as a deicer Friday in Sloan Hall.

HANNAH WELZBACKER, Evergreen reporter

A WSU researcher found that a chemical used on the roads during snowy weather has dangerous, and hidden, effects on the health of roadways and bridges.

Xianming Shi, WSU civil and environmental engineering associate professor, found that samples of concrete exposed to magnesium chloride with repeated freeze and thaw cycles lost more strength than samples exposed to rock salt.

Deicers work by reducing the freezing temperature of water, Shi said.

“There is a good reason why we use salt,” he said. “We want winter safety and we want to drive fast on winter roads. But that leads to a lot of unintended consequences.”

Shi said the most concerning finding was the fact that the samples with damage showed no visual signs of it.

“One alarming finding is that our traditional inspection methods are failing the purpose,” Shi said.

He said this finding is similar to humans being sick. If there are visible symptoms someone can go to the doctor before the problem gets out of hand.

This work was funded by the U.S. and Oregon Department of Transportation. Shi said Oregon is unique because they rely primarily on magnesium chloride deicer instead of a combination of methods.

He said magnesium chloride is thought by some to be more environmentally friendly; however, this is still debated. It is difficult to quantify the risk because it can vary based on the receiving environment.

Art Garro, City of Pullman maintenance and operations superintendent, said Pullman currently uses magnesium chloride, but the amount used has been reduced over time.

“We have cut back on what we use, but there are certain things that magnesium chloride — you just can’t beat it for what you are trying to do,” Garro said.

Magnesium chloride works well for getting rid of black ice, in particular, Garro said. If the city uses solid rock salt there is nothing to bind it to the road and the salt gets pushed to the side of the road.

Shi’s worked on deicer research previously, but his study in 2003 only examined whether certain deicers affect water quality adjacent to roads.