Rock salt and other de-icing products melt snow and ice, making it easier to plow or shovel a driveway or sidewalk. De-icing products sometimes damage the structural integrity of concrete by accelerating freeze-thaw cycles. But asphalt is not affected by salt, according to the Cornell Local Roads Program, which provides training for New York highway and bridge workers.
Rock salt, a form of sodium chloride, is the most commonly used ice-control chemical in the world, according to the Cornell Local Roads Program. Like other types of salt and de-icing chemicals, rock salt decreases the freezing temperature of water. Salt runoff is harmful to grass and other plants, causing stunted growth and leaf browning. Soaking affected plants with an inch of water three or four times in the spring or adding gypsum to the soil helps plants recover. Salt used to melt ice also marginally increases sodium levels in drinking water.
Asphalt is a sticky substance that occurs in nature. Asphalt used in driveways, however, is derived from petroleum. Asphalt is the glue that holds other particles together in a paved road or driveway. Asphalt driveways and roads typically sustain potholes and other damage when water underneath the asphalt freezes and melts. Cold weather can also cause asphalt to become more brittle and crack.
Applying rock salt to your asphalt driveway before or just after the snow or rain begin will melt the snow and ice most effectively. If it's windy, wet the rock salt first to help it stay on the driveway. After snow and ice have formed, apply rock salt to your driveway according to label instructions. Apply an even layer, and don't use more than what's recommended. Using an abrasive, such as gravel or sand, along with rock salt, will improve traction and make walking and driving safer. Shovel your driveway after the rock salt has taken effect. Store salt carefully to prevent pollution.
If environmental concerns discourage you from using rock salt to de-ice an asphalt driveway, you can remove snow and ice by shoveling. You can also use abrasives without using rock salt. Do not use fertilizers or other unapproved chemicals to melt ice, because these products pollute the water supply. In addition, avoid using formate/acetate-based de-icers on asphalt driveways. These formulations damage asphalt, according to a 2009 article in The Open Civil Engineering Journal.