Due to the excellent abrasion resistance of galvanized reinforcing steel no special requirements are needed when installing it on site.
This, in conjunction with the galvanized reinforcing steel’s improved bond strength, mean that no extra steel needs to be installed (some protective coatings require overlap lengths that are an additional 20% – 50% greater compared to uncoated reinforcing steel).
Like uncoated reinforcing steel, no specific weather conditions are required for installation and due to the surface coating, galvanized reinforcing steel is much cleaner to work with. Also, because the coating is metallurgically bonded with the steel, little damage is created during installation.
While galvanized reinforcing steel does have significantly improved installation and corrosion resistance properties compared to uncoated reinforcing steel, the most critical factor in the protection against corrosion in concrete structures is the use of good concrete quality practices.
This is governed by:
- Concrete materials
- Mix proportions
- Adequate cover
The use of galvanized reinforcing steel is not an excuse for poor concrete practice!
Mixing hot dip galvanized and uncoated reinforcing steel
In concrete, corrosive reactions would not be expected to occur between uncoated and galvanized reinforcing steels so long as the two metals remain passive. To ensure this is the case, the concrete cover over uncoated reinforcing steel and connections should not be less than the cover required to protect uncoated reinforcing steel alone under similar conditions.
Where hot dip galvanized reinforcing steel is used it is best practice that all steel in contact with the reinforcing steel should be galvanized including tie wire, inserts and bar chairs or that non-metallic or plastic-coated ties and bar chairs be used.
If hot dip galvanized reinforcing steel is placed in contact with uncoated reinforcing steel in areas prone to corrosion, the coated steel will sacrificially protect the uncoated steel, resulting in a reduction in the life of the coating near the area of contact. Should contact with uncoated reinforcing steel be unavoidable and a concern, polyethylene and dielectric tape can be used to provide electrical insulation between the two metals.
Galvanized tie wire or plastic clips should be used when assembling or installing galvanized reinforcing steel. and bar supports also should be galvanized steel, plastic, or some other inert material such as masonry. If mechanical couplers are being used, they should be galvanized as well.