A common area for spalling concrete is underneath exterior formed concrete stairs. The spalling is caused by water seeping into the concrete corroding the rebar. As the rust forms on the rebar it expands causing the concrete to break off.
To prevent this from happening, you should have the top surface of the concrete stairs waterproofed. Waterproofing concrete involves prepping the concrete and then troweling on a special waterproofing cement. This will help prevent water from soaking into the concrete corroding the rebar.
Today we fixed some concrete stairs that had numerous areas that were spalling. We began repairing the concrete stairs by chiseling out the loose and hollow areas.
Spalled Areas on Concrete Stairs
Chiseling Hollow Areas in Concrete
After chiseling out all of the hollow areas we cleaned the surface with water and a brush and then applied a repair mortar to the spalled areas.
Spalled Areas Chiseled Out
Applying Repair Mortar To Spalled Areas
After Applying Repair Mortar
Once the repair mortar was hard, we resurfaced the whole stairs to blend it all in.
Before Concrete Stairs Repaired
After Concrete Stairs Repaired