Calcium chloride is excellent for melting ice and snow and is better for your surfaces than rock salt.  It is more expensive, but delivers several advantages over rock salt.  Calcium chloride can be effective at temperatures as low as -25 F, while rock salt works loses its effectiveness at temperatures below 15 F.

Rock salt can poison soil and can also be damaging to trees and other vegetation.

Rock salt can damage concrete.

Rock salt can also be harmful to pets.  Pets will lick their the irritated paws to remove salt, possibly ingesting the salt.

For the reasons above, Integrity Landscape Services always recommends calcium chloride to reduce slippery driveways and walkways.