How Does Road Salt Damage Concrete?
When you have a concrete sidewalk or driveway at your home, you may not know that salt can be damaging. If you live in an area where there is minimal snowfall and ice, then the concrete of your property would not be exposed to road salt. However, areas in which snow and ice are prevalent, road salt is commonly used to de-ice the roads and it can affect the concrete areas of your home such as walkways and driveways.
Salt damage occurs when concrete is exposed to de-icing salts. Safe de-icing chemicals such as sodium chloride, calcium chloride, and potassium chloride can all affect the concrete of your property. Each is mildly acidic and will attack the bonds that work to hold the concrete together. Because salt is a mild acid it will lower the pH level in the concrete. The reaction from the acid will result in attacking of the concrete paste and aggregate which will weaken the structure of the area. The pore size of the concrete will grow and water and chemicals will work their way into the material. This, in turn, will expose the concrete to worse freeze/thaw cycle damage.
Salt also attracts and retains water due to being hygroscopic. This means that when salt is placed on concrete as much as 10% more water will be attracted inside the pore structure. There will be less room available for expansion of the pore structure which will create pressure inside the concrete when freezing occurs. This will cause the surface to chip, flake, and pop. This is what is known as spalling.
Carbonation is also accelerated with salt exposure which will slowly reduce the levels of pH in the concrete. This happens as the salt is contacted with carbon dioxide. When salt is placed on concrete, it will provide a source of chlorides which will cause corrosion.
Overall, exposure to salt will change the concrete and make it appear as if it is wearing away or being eaten away. Pitting occurs and the concrete is not smooth and clean looking. It is best to try and avoid salt exposure to your concrete but sometimes this is unavoidable when you live in an area where de-icing chemicals are used.
Thankfully, concrete companies can offer solutions to protect concrete from salt damage and other issues. Penetrating sealers can be used to cover the concrete and protect it from salt and water damage. This will help to prevent freeze and thaw damage as well as repel water and avoid other issues that are common to concrete wear and tear.
When concrete is first installed, it is recommended to have such solutions used so that concrete is protected from the very beginning. Old concrete can also be treated with such solutions to provide a barrier to avoid salt, water, and freezing damage. Have your concrete treated so that you can rest easy knowing that your concrete is protected and will look great, working perfectly for many years to come without succumbing to damage.