Road salt ruins boots, carpets, and our vehicles, but it’s doing a lot more damage than that. Salt is not only building up in our rivers and creeks, it does billions of dollars of damage every year to our roads, buildings and concrete structures.
Those costs have many municipalities looking at ways to use their salt more efficiently, while also experimenting with biodegradable alternatives for keeping our roads clear.
Those alternatives include the leftover juice from beet sugar processing, as well as the salty brines left over from pickle and cheese production.
Robin Valleau and Jamie Summers, two Queen’s University biology graduate students who have studied the effects of road salt, say all three alternatives work in similar ways.
“They are a carbohydrate additive that is added to a salt brine that increase the melting potential of the salt, so it works down to -20 C, whereas regular salt works only to -12. It means adding less salt to the roads,” Valleau told CTV’s Your Morning from Kingston, Ont. Monday.
The cities of Toronto and Calgary have both been using beet juice when temperatures dip into the very frigid temperatures when regular salt stops working.
Another advantage of beet juice is that it’s sticky, so when it’s sprayed before a storm, it can keep ice from bonding to a road’s surface, and it can stay on the road surface for two to five days.
While one might assume the beet juice can stain roads a wine-coloured hue, Valleau notes the diluted brine doesn’t leave much residue behind.
“Some communities have reported a slight odour with these alternatives. But when you look at the ecosystem benefits from switching then possibly we can get over a slight smell some of the time,” said Valleau.
Other towns have been trying other materials meant to reduce slipping on the roads. Many communities in the north have long used gravel to increase traction, while the town of Rosemere, near Laval, Que., has been using wood chips treated with magnesium chloride. Not only are the wood chips proving effective they are also biodegradable and break down naturally over time.
“These alternatives they don’t have melting potential for the ice, they just provide more traction between the tire and the road surface,” said Valleau.
But while the alternatives are interesting, there’s good reason why cities and municipalities have relied on road salt for decades: it’s cheap and it works.
At $50 a tonne, salt costs a fraction of the alternatives. Given that an estimated 5 million tonnes of road salt are spread on Canadian roads every year, costs like that can add up.
But salt causes an estimated $5 billion in damage annually to Canadian infrastructure, particularly bridges.
“It doesn’t so much affect the asphalt itself, but the steel rebar within the structures,” Summers said.
Salt has been cited as a contributing factor in the corrosion of bridges and highways, including Montreal’s Champlain Bridge and Toronto’s Gardiner Expressway. Salt also played a role in the 2012 collapse of the Algo Centre Mall in Elliott Lake, Ont. roof.
Salt is relatively harmless in low concentrations but when it finds its way into rivers and lakes, there is no easy way to remove it. Concentrations build up year after year, until they becomes toxic to aquatic life, including fish, amphibians and plants.
“When you take into account the value of the ecosystem that we get from lakes and rivers, I believe it’s certainly worth it to use alternatives,” Valleau said.
