Concrete spalling is one of those terms not found in everyday language, but I will bet you’ve seen this problem numerous times. Concrete spalling is where the surface of a driveway or sidewalk erodes away. This condition is most common in northern areas where ice is common during the winter.
The freeze-thaw cycles and deicing chemicals used to keep a driveway clear create a nasty combo for unsealed cement. Water from melted snow seeps into the capillaries of the cement re-freezes. The freezing process puts a lot of pressure on the cement and starts to create the spalling effect. The deicing chemicals, most commonly rock salt, can create the same effect. If too much salt is applied, it begins to collect within the top layers of the cement. It will then crystallize and put pressure on the concrete. The last source of concrete spalling comes from the rebar. If it is exposed to air and moisture, it will begin to corrode and more pressure is applied to the concrete.
All of the sources of the problem stem from water issues. If you can prevent water from seeping into the concrete, then you can prevent spalling. The best solution is to use a concrete sealer. Apply a concrete sealer after letting a new driveway settle for 30 days. From that point forward reapply a sealer every two years.
To apply a sealer, measure the square footage of the concrete and buy the appropriate amount of product. Next, clean the surface of dirt and other debris. The temperature will probably need to be above freezing (depends on the product) and the surface free of water. Pick a day when there is no rain or high winds in the forecast. Apply the sealer evenly while avoiding puddling. The sealant will need at least a couple hours to settle.
Repair Concrete Spalling
Repair the concrete on driveways and sidewalks to increase curb appeal. Concrete spalling is best repaired with polymer modified cementitious coating. The cement component will give the cured product a hard finish that blends in with the rest of the driveway or sidewalk. The polymer component gives it an adhesive trait that helps the compound fill in the hole. However, the surface must be prepped for the product to work. Otherwise, your home’s cement will be in the same problematic scenario again next year.
Use an acid wash if the surface is loose. After the surface is clean, apply the primer to give the surface adhesion. Use a broom to apply the primer evenly.
Make sure the repair product is the same strength and mix up the solution in a bucket. Then pour the mixture over the spalled areas. Use a squeegee to evenly distribute the material. Wait 24 hours for the mixture to harden and visually inspect. You can apply a second coat if there are still depressions. After letting is completely settle for week, apply a cement sealer to give it long lasting protection.
If you would like to see a video on the subject, check out the Concrete Network here.