Currently there is only one commercial source for CMA, using the reaction of acetic acid with dolomitic limestone for production. Acetic acid, the costly component of the compound, is manufactured from natural gas or petroleum, though small quantities have been produced by biodegradation of agricultural wastes.

The compound is available as pellets or powder. Though not as soluble in water as NaCl and CaCl

2

, solutions can be made for use as a pre-wetting agent or straight chemical application.

It is not a highly effective de-icing chemical in solid form because of its affinity for water and its light particle mass. Its benefit is that it makes snow mealy so that it doesn’t compact.

CMA is primarily a mixture of calcium and magnesium acetates, produced with a 3/7 Ca/Mg ratio which was found to be optimum in previous FHWA studies. The eutectic temperature is about -18 degrees Fahrenheit at a concentration of 32.5 percent.

When CMA degrades, the calcium and magnesium elements are said to actually improve the water and air permeability of the soil by restoring sodium-compacted soils.

Since acetate degrades into carbon dioxide and water and is a natural component of plant decay, CMA is appropriate where roadside vegetation, crops, or ground water are especially vulnerable. Because it is less corrosive than salt, some agencies prefer CMA for use on bridges, parking structures, sidewalks, and certain road surfaces (

caution

: it does cause major scaling).

The cost of CMA is approximately $600 per ton whereas salt generally costs $20 to $40 per ton. Some advocates of CMA argue that the initial costs may be misleading because replacement costs for roads and bridges damaged by chloride-related corrosion should be factored into the overall figures.

The pellet form of CMA is usually preferable to the powdered form, since the powder dust is less controllable. The pellet form of CMA does not bounce off the road before melting and its residual action can reduce reallocation frequency.