The Effects of Salt on a Sidewalk & Lawn

How Salt Works

• At 32 degrees Fahrenheit, water reaches an equilibrium between solid and liquid state. Water molecules are melting and freezing at a balanced rate. If salt is added, it causes two events to occur. It lowers the freezing point of water, and it prevents water molecules from binding with other water molecules. Ice continues to melt until the outside temperature drops below 15 degrees Fahrenheit. At this point, salt, specifically sodium chloride, becomes ineffective.

Salt and Concrete

• Rock salt, or sodium chloride, doesn't react with concrete. It does increase the number of freeze-thaw cycles that a sidewalk undergoes. When water freezes, its volume increases by 9 percent, according to AskTheBuilder.com. If concrete hasn't been cured properly or if air bubbles were trapped in the concrete before it set, this expansion increases pressure, which could break apart the concrete sidewalk.

Salt and Grasses

• Based on the Law of Osmosis, water will flow from a region of lower concentration to one of greater concentration. Applied to saline soil conditions, if salt concentrations increase in the soil where grass grows, water will be drawn out of grass cells to the external soil. In addition to dehydration, root systems are unable to absorb water and other nutrients. Not all grass varieties suffer. Turf grasses can withstand saline soil concentrations better than others. LifeandLawns.com recommends that you plant your lawn with grass seed mix that has a high percentage of turf fescues, perennial rye grass and bluegrass. These grassy varieties are more salt tolerant and may survive salt splash.

Damage Prevention

• If your concrete sidewalk needs to be replaced, AsktheBuilder.com recommends a concrete mixture with "a minimum of 564 pounds of cement per cubic yard and a minimum amount of water." Concrete should be cured at or above 50 degrees Fahrenheit for at least seven days before the first winter snap. Another option is to replace concrete sidewalks with brick or inlaid stone. And instead of a deicer made with rock salt or calcium chloride -- a deicer which does chemically react with concrete -- use a magnesium chloride deicer or a "green" version with volcanic granules. Magnesium chloride is less toxic to plant life and continues to melt ice at temperatures below zero.