Road salt additive turning Montreal streets, sidewalks blue

Magnesium chloride-laced salt is tinting Montreal roads and sidewalks blue. It's supposed be more effective and longer lasting than ordinary road salt.

Magnesium chloride-laced salt shown to reduce amount of regular salt needed by 10 to 30 per cent

Salt mixed with liquid magnesium chloride is leaving a trail of blue on Montreal's streets. 0:55

Montreal streets are tinted blue these days – thanks to salt moistened with liquid magnesium chloride.

The mixture is said to be more effective than ordinary road salt because it stays on the road longer and sticks to icy surfaces better. 

City of Montreal spokesman Philippe Sabourin said the city is studying how well it works. 

"We want to verify if optimizing the efficiency of de-icing products helps reduce the number of applications necessary and cuts down on the amount entering the environment," said Sabourin.

Sébastien Sauvé, a professor of environmental chemistry at the Université de Montréal, said liquid magnesium chloride isn't very toxic and has been shown to reduce the amount of road salt used by 10 per cent to 30 per cent.

"That kind of reduction translates into [fewer] trips and less gas consumed by trucks – and that's significant," Sauvé said.

Less degradation

Sylvain Ouellet, the spokesman on environmental issues for Projet Montréal, said reducing the amount of salt used on the roads has the added benefit of slowing down the deterioration of roads and sewers.

"There's a Canadian study that shows every dollar of salt on our roads translates into the equivalent of five dollars worth of degradation to underground infrastructure," he said.

For the moment, the experimental mixture only represents a tiny percentage of the 130,000 tonnes of road salt and 34,000 tonnes of abrasives spread on Montreal's roads and sidewalks every winter.

Ouellet said the city needs to do more to reduce those amounts.

Then there's beets

He points to a Scandinavian innovation that can gauge how slippery a surface is and adjust the amount of salt that's spread.

In December, Laval introduced a de-icing product derived from a sugar beet extract on its streets.

You might think that might mean that Laval streets would be tinted pink, but Laval officials said the city uses a white-beet source. 

Based on a text by Radio-Canada's François Cormier


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