Before revision: To properly protect the steel the concrete needs to cover the steel by more than the minimum thickness, not have large cracks and not have it’s chemistry altered by environmental factors like chloride attack from deicing salts, carbonation, etc.. ACI and PCI (American Concrete Institute, Precast/Prestressed Concrete Institute) codes specify minimum cover thicknesses depending on the application of the structure.
After revision: To properly protect the steel the concrete needs to cover the steel by more than the minimum thickness, not have large cracks and not have its chemistry altered by environmental factors like chloride attack from deicing salts, carbonation, etc.. ACI and PCI (American Concrete Institute, Precast/Prestressed Concrete Institute) codes specify minimum cover thicknesses depending on the application of the structure.