Unless you live in a sub-tropical area, battling ice and snow on concrete steps, walkways and driveways is an annual winter event. Salt is the most frequent weapon used to wage the war. The down side is that it causes damage to your concrete. You may not notice the flaking, spalling and pitting until spring, but it will happen. Perhaps it seems like the price that has to be paid to keep ice under control, but is it? Here are the most common ways that salt damages concrete:
Salt is corrosive and concrete is porous. These facts are important when you realize that metal rebar is used within the concrete to stabilize and strengthen it. The salt will mix with the water from the melted snow and ice and seep down to the rebar. Over time, it will corrode the metal and weaken the concrete surface. Before you know it, you have large cracks that seem to develop out of the blue.
The gradual rust build-up around the rebar will also create immediate damage such as flaking and spalling. As the metal weakens and rust expands, the more deformed the concrete will become until it finally begins to break apart. You might not be able to see the initial damage within the concrete, but it makes its way to the surface over time.
Water and Salt Join Forces
Salt works against snow and ice by reducing the temperature at which the water will freeze. The more it snows, melts and adds to the mix, the weaker the salt becomes. This water gathers in the pours of the concrete. When it refreezes it expands. This causes pitting and spalling. It’s the combination of the salt and water that lead to the damage. The more the temperatures fluctuate, the worse the damage will be. Every instance of refreeze creates pressure on the concrete.
The salt alone can damage the surface of the concrete as well. Have you ever notices a white look to the surface of the concrete after using salt to melt the ice and snow and the surface dries? The salt will settle into the concrete pours and crystalize. This causes palling and flaking of the surface. The term for this is subflorescence. Damage of this type can be seen after the first winter.
How to Avoid Salt Damage to Your Concrete
Use Salt Responsibly
If you need to use salt to de-ice your concrete, use it with the knowledge that it should be removed as quickly as possible. Use enough to melt the snow or ice and scoop it away. Leave the surface to then air dry. It will decrease the chances for any type of damage to take hold. Sprinkle, let it melt, sweep or scoop away. Making this your winter mantra could save your concrete.
Seal the surface of your concrete using a quality sealant product. This will ensure that the water and salt cannot seep down into the pours of the concrete. Many of these products last for years and are relatively easy to apply.