In an average year, five million tonnes of road salts are used each year as de-icers on roadways in Canada. While road safety should remain a top priority, heavy use of salt raises concerns for environmental protection and can cause billions of dollars in damage every year to structures like roads, bridges, buildings, and even cars and salt trucks.
Exactly how salty can melting snow and ice get?
The melting water running off salt-treated roads and parking lots can have salt concentrations higher than seawater. This can be toxic to aquatic life.
And while road salt remains attractive because it is the lowest cost option for managing snow and ice, that’s not where the costs end. Salt speeds up the corrosion of metal rebar inside concrete, damaging surrounding buildings and infrastructure. Montreal’s Champlain Bridge and Toronto’s Gardiner expressway are two examples of salt-damaged structures.
In recent years, several pilot projects have targeted salt reduction while maintaining passable roads.
Biodegradable wood chips gain traction
Salt only works at mild freezing temperatures, helping keep roads clear down to around -15oC. Beyond that, sand can help lend traction to passing cars, but the clean-up effort required afterwards is significant.
Wood chips are an alternative commonly used in Switzerland, and they’re biodegradable, which means that after being applied, they can be left to degrade on their own. They work down to -30oC, and are more long-lasting than an application of salt. Mixed with magnesium chloride, the chips are better able to stick to the roads.
The wood chips are being tested on a few streets in Rosemere, a Montreal-area suburb, and the results are positive so far. They can be applied using standard salting and sanding trucks.
Sweet solution could help “beet” icy roads
Toronto, Calgary, and parts of Quebec and Northern British Columbia are already reducing their salt use by spraying a mixture of salt and beet juice, a byproduct from sugar beet processing.
The sticky beet juice helps the solution stick to roads, providing greater staying power. The sugar also assists in de-icing, reducing the need for salt and further expanding the useable temperature range down to -30oC.
Similar food byproduct approaches include using pickle juice or cheese brine, both of which already contain salt, but also contain other organic compounds to help with de-icing.
All of these alternatives cost more to de-ice the roads than regular salt, which means that for the most part they are reserved for use at colder temperatures. But considering their other benefits, they are a welcome addition to the Canadian winter toolkit.