UMass Amherst Researchers Study Road Salt Substitute to Keep Highways, Environment Safe

AMHERST, Mass. - Just because crocuses are blooming and potholes are being patched doesn''t mean that life is any less hectic for University of Massachusetts engineers who are working to keep the roads safe when the snow falls.

A team of UMass researchers has spent three years studying the biodegradability of a possible road salt substitute, says David Ostendorf, of the University''s civil and environmental engineering department. The study, conducted for the Mass. Highway Department and the Federal Highway Authority, has concluded that calcium magnesium acetate (CMA) may be a "tool in the arsenal" in keeping roads safe in environmentally sensitive areas.

Scientists aren''t necessarily against the use of salt, says Ostendorf, who stresses that a high priority is placed on roadway safety. "Anybody who has driven on a road that has not been salted, and has skidded all over the road knows that, as with any environmental issue, you have to consider alternatives," he says. "There isn''t a highway engineer in the country who''s going to rest until the pavement is safe to drive on."

The cheapest and most effective way to make pavements safe in snow is by spreading down sodium chloride - salt - or "Pre-Mix," a combination of sodium chloride and calcium chloride, which melts snow and ice by lowering the temperature at which freezing can occur. Sand is often added to provide traction. But the traditional salt-and-sand method may not be an attractive option in areas that are ecologically sensitive, or where salt can seep into drinking water. Excessive salt can potentially cause a variety of health problems in human beings, including high blood pressure. The degree of damage or injury depends on the amount of salt that is used, and the proximity of streams and groundwater.

Studying the biodegradation of CMA has been a team effort in the civil and environmental engineering department. Along with Ostendorf, who is responsible for chemical analysis and mathematical modeling, the team includes geotechnical engineers Don DeGroot and Al Lutenegger, and microbiologists Sharon Long and Sarina Ergas.

CMA works by melting ice and snow. Unlike salt, however, the residue left by the substance is consumed by microorganisms, so that only negligible amounts hit the water table. Ostendorf stresses that CMA has its drawbacks. For example, it has a tendency to clump, making it difficult to spread on the roads. Furthermore, it''s far more expensive than salt. "CMA is not something you would use indiscriminately; it is to be used judiciously and selectively," says Ostendorf. "But it does have its place. It''s a tool in the arsenal."