Sodium Chloride (rock salt)
Sodium chloride (NaCl) also known as rock salt was first used as a deicer in the 1940's. It is an effective deicer for areas that receive road traffic. It draws heat from the environment rather than releasing it and it loses most of its deicing effectiveness when temperatures are below 25 degrees F. Heat generated by the friction of moving traffic on busy roadways assists rock salt's effectiveness.
Sodium chloride or rock salt is the most commonly used ice melter. It is inexpensive and melts ice.
Compared to other materials, though, it has limited effectiveness in very cold temperatures. It will not melt ice at temperatures below 20o F, and it may be harmful to vegetation, but is considered safe for concrete.
Sometimes sold mixed with fine gravel, or cinders, even sand when sold in bulk. This helps provide increased traction, until the salt can melt ice. Salt is harmful to concrete surfaces, more harmful on lower grades of concrete. It is also damaging to plants, flowers, and shrubs. It is corrosive to metals, except stainless steel. Its relative cost is low. Temperature greatly affects how well it melts. The colder it is, the less it melts. Coarse salt alone weighs about 50 pounds per cubic foot. That's about 1350 pounds to a cubic yard. In bulk, it is commonly sold by the ton. So a ton would be about 1.48 cubic yards. I'm sure with the grit mixture, the weights are higher.
Rock salt is the most commonly used ice melter. It is inexpensive and melts ice. Compared to other materials, though, it has limited effectiveness in very cold temperatures. It will not melt ice at temperatures below 22 degrees and it may be harmful to vegetation, but is considered relatively safe for concrete.
Sodium chloride provides adequate economical performance at temperatures at or just below 32° F. As temperatures drop below freezing, its ice-melting performance slows substantially. Most frequently used deicer for highway application; often treated with liquid calcium chloride or mixed with calcium chloride to improve low-temperature performance on highways.
Irregularly shaped sodium chloride crystals.
Relative deicing speed
Slower than calcium chloride.
Lowest practical temperature
Down to 20° F.
Effect on concrete
Does not chemically attack concrete. Can cause damage from freeze-induced expansion pressures by increasing number of freeze/thaw cycles.
Effect on vegetation
Sodium ion is toxic to vegetation.
Leaves a white, powdery residue when it dries.
Manufacturer's recommended application rate