People living in climates that are plagued by snow and ice during the winter often turn to de-icing salts to make their driveways and walkways safer. Rock salt is a common substance for this task, but there is concern that using salt on concrete causes unsightly and potentially costly damage. Before using salt on concrete, it is worthwhile to consider both the pros and cons.
Walkways that are covered in snow can be a big hassle for homeowners, and if shoveling is too difficult a task to complete as often as necessary, the snow can get packed down into a hard layer by foot traffic. Hard-packed snow can be slippery and difficult to navigate, which becomes a safety concern for many homeowners. Similarly, icy surfaces can be treacherous and raise liability concerns. These fears can be put at ease by sprinkling salt on walkways to melt the snow or ice and make the surfaces easier to navigate safely. Certainly, the peace of mind that comes with de-icing surfaces is a benefit of using salt on concrete.
Unfortunately, when salt is spread on concrete to melt snow and ice, the product is usually a thick, wet slush. While this slushy aftermath is far less treacherous to travel across than ice or packed snow, it can be very unpleasant. Lots of shoes, and almost all pant hems, are no match for the freezing penetration of the slush produced by putting salt on concrete. It is very sloppy, and can soak through outer layers, leaving feet wet and cold. Furthermore, when temperatures drop and slush that has been walked through re-freezes, it can create a landscape that is even bumpier and trickier to walk on than before.
Probably the most notable, if contested, aspect of using salt on concrete is that doing this may cause damage to the concrete surface itself. Concrete is porous and very susceptible to water absorption. When salt is sprinkled on snowy or icy concrete surfaces, the melting snow and ice produces water. During periods of warmer temperatures, this water is likely to be absorbed into the concrete, along with traces of the salt and whatever chemical additives it has been mixed with.
If chemicals are present, as is sometimes the case with rock salt de-icers, it is possible that they leach into the concrete and sacrifice its integrity from the inside out. The greatest concern related to water absorption, however, is related to the freeze-thaw cycle. Water is absorbed into concrete, but when temperatures drop, it freezes into ice and consequently expands. Expansion can result in disruption and cracking of the cement.
Typically, good quality cement that is properly poured will be able to resist damage from thawing and freezing. Typically, though, there is really no way the average homeowner can tell what the quality of his or her cement is. To be sure that using salt on concrete will not cause damage, clear cement sealers can be applied during the more temperate months.