Industry Issues: Magnesium cloride’s effect on trucks and trailers

by David Bradley

Winter is upon us, and for those who regularly travel the nation’s highways, adequate and timely de-icing is of primary importance. Safety is the foremost concern. Increasingly, so too is the environmental impact of de-icers. And for the trucking industry, the corrosive effect of de-icers on equipment is also a consideration.

Road salts include sodium chloride, which is applied after a snowfall, and magnesium chloride, which is applied prior to snowfall or icy conditions.

Both naturally lower the freezing temperature of water. They also have some corrosive properties. But the biggest knock against both is that environmental research has identified them as having a negative impact on the environment.

Their run-off increases harmful concentrations of chloride ions in water and soil next to roads where it is applied and in areas where removed snow is dumped. Both have been listed as toxic under the Canadian Environmental Protection Act.

So, what are we to do in a country like Canada where de-icing is essential? Some researchers say magnesium chloride is less harmful than sodium chloride.

Add to that the fact that some road authorities believe magnesium chloride to be more effective (faster) than sodium chloride. I am in no position to know whether it is or isn’t. Nevertheless, magnesium chloride appears to be emerging as the de-icer of choice in Canada.

But is magnesium chloride really the right substance to use for de-icing Canadian roads? The question has arisen recently as a result of findings, both empirical and anecdotal, that indicate the substance may also cause increased corrosion of vehicle parts, particularly in humid climates such as ours.

Magnesium chloride is applied in liquid form, as stated above usually prior to snowfall or other ice-making conditions.

Driving over the freshly applied liquid causes it to spray up and onto vehicles travelling the roadway. This material is initially benign, but mixing with water and atmosphere over a period of time causes chemical changes to take place on vehicle surfaces. Galvanic action between dissimilar metals and interaction with electrical current are the major reactions that take place over an extended period after initial exposure.

Industry concern regarding the use of magnesium chloride and its impact on truck components has been discussed throughout North America. The Technology and Maintenance Council (TMC), a U.S. trucking industry authority on maintenance issues, has identified the effect of magnesium chloride as a serious problem facing the industry. A 2002 research paper from the Colorado Depart-ment of Transportation confirmed that in humid environments magnesium chloride is much more corrosive than sodium chloride.

Brakes, fuel tanks, radiators, electrical systems, suspensions, engines and trailers are all susceptible to corrosion. In Canada, corrosion problems have already been reported by member carriers in jurisdictions where magnesium chloride is reportedly being used. There is also growing evidence that there are negative effects on concrete roadway surfaces, bridge structures and buildings at or near highways where magnesium chloride is used.

While there are no doubt environmental, liability and highway safety benefits derived from the use of magnesium chloride for de-icing, there are also clearly some problems that need to be addressed, and not only by the trucking industry. Part of the solution could be altering the formulation of products containing magnesium chloride, or altering the timing of their application to roads, so its corrosive effects are mitigated.

Either way, Canadian jurisdictions need to take a closer look at magnesium chloride and ask whether the benefits currently outweigh the disadvantages.

– David Bradley is president of the Ontario Trucking Association and chief executive officer of the Canadian Trucking Alliance.

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