To minimize the impact on concrete, ice and snow should always be removed promptly and any excess deicer brushed away after sidewalks have been cleared. Recent reports from highway departments in Massachusetts and Illinois indicate that CaC12 can shield against frost and ice formation for several days following application. The highway superintendent in Ogle County, Illinois, described it as an almost shield-like effect. Even when diluted to a 20 percent solution, it is effective to minus 4 degrees Fahrenheit. This residual effect can be especially helpful when one storm quickly follows another.
Most deicers dry to a white powdery residue.
This includes rock salt, urea, potassium chloride and blends of those materials. The two other deicers, magnesium chloride and calcium chloride, leave a clear brine solution. Regardless of the deicer, again, prevention is the best approach. Walk-off mats are one of the simplest yet most effective ways to cut down on tracking. Studies show that at least four feet of mat is needed with six to ten feet for higher traffic areas.