Repairing Concrete Spalling in Its Early Stages
Spalls often happen in concrete due to the rebar being exposed to moisture seeping into the concrete, and once this happens, the damage can become very serious very quickly. However, if concrete spalling is caught in its very early stages, you can reverse the process and fix the damage without having to contact a professional, which can be costly and time-consuming.
When can concrete spalling be handled by a do-it-yourselfer?
If the concrete damage is shallower than a third of the thickness of the concrete, then it can be repaired by a nonprofessional. However, if it is below a third of the thickness of the concrete, then a professional may need to be called because the steel bars might need to be replaced, which could mean a full-depth restoration. If the damage is done in an area that might cause structural damage to the rest of the home, such as a supporting wall, then a professional should be called to assess the damage.
How do you fix the early stages of concrete spalling?
Fixing the early stages of concrete spalling will depend on where it is happening and the extent of the damage. If the rebar is exposed and damaged, be sure to clean it before beginning the restoration process or it will keep rotting beneath the new layer of concrete. Use a wire brush to clean the rebar carefully and add a protective coating to stop it from happening again.
If the concrete is over a driveway or a horizontal surface, such as a sidewalk, then a cementitious overlay can be applied. After the overlay has cured, then a waterproofing membrane should be applied to prevent further spalling. For any option to be effective, be sure to remove the concrete to a depth of 1.5 inches or more. Clean and remove all the debris before beginning the repairs.
It is important to clean all fragments and fine specks from the concrete before repairing it and allowing it to dry before applying the concrete. Otherwise, contaminants in the particles and the debris, or water from cleaning the surface, can cause further spalling with the fresh batch of concrete.
If you are using a patching material, which is made out of Portland cement or epoxy, then be sure to understand that these mixtures dry and react quickly. Therefore, you should only mix what you plan to use within fifteen minutes. In addition, the air temperature must be above 40 degrees Fahrenheit; else, the repairing material will not work. Be sure to use only supplies with an expansion factor that is similar to concrete.
Lastly, joints have to be repaired and restored properly to allow for the expansion of the concrete slabs. Therefore, it is best to contact a professional if spalling has happened where there are joints.