Salt can damage concrete because it is porous and salt lowers the freezing point of water,  leading to a repeated freeze-thaw cycle that can significantly weaken the surface of the concrete. When salt touches concrete, the difference in pH between the two causes the chemical bonds within the concrete to break down. Calcium hydroxide in concrete reacts with the calcium chloride in salt, forming calcium oxychloride which can cause internal cracks and ultimately crumbling and surface flaking called spalling. Salt is a mild acid and lowers the pH in the concrete, which attacks the concrete paste and aggregate, weakening the structure and strength of the concrete.Please take this information into consideration when dealing with ice, instead of using salt there are alternatives like sand and cat litter. Remember to use plastic shovels when shoveling snow,using metal tipped shovels will scratch the sealer off.