Bending, welding, repair, handling, transport and storage
Bending
Minimum pin diameters used to bend reinforcing steel (internal bend diameters) are given in AS 3600 and must be followed to ensure the integrity of the coating.
Prior to galvanizing, bend diameters should be consistent with good practice to minimize cold working of the microstructure (which may result in strain age embrittlement).
After galvanizing, excessive cracks may form in the coating if too tight a bend radius is used.
The minimum internal bend diameter for reinforcing steel bent either before or after galvanizing depends on the thickness of the reinforcing steel. For 90° bends where straightening is likely to be performed after galvanizing the recommended internal bend diameter is shown below.
- For reinforcing steel with a diameter ≤ 16 mm – a minimum pin diameter of 5 times the reinforcing steel diameter
- For reinforcing steel with a diameter > 16 mm – a minimum pin diameter of 8 times the reinforcing steel diameter
Re-bending after straightening may cause cracking of the coating. If this occurs, cracking of the coating may be repaired using the requirements shown below.
Welding
Galvanized reinforcing steel can be welded, however some changes in welding technique are required. The preferred method is to remove the coating by either grinding or filing until the base steel is exposed before welding. Where the coating has been removed or damaged by welding, repairs must be made as described below to ensure adequate corrosion protection of the damaged surface.
Repairs
Any repairs to damaged coatings should be carried out as per the instructions in AS/NZS 4680 using either:
Zinc-rich paint: the most common and convenient method (≥ 85% to < 94% metallic zinc in dry film), with total dry film thickness minimum of 100 µm for optimum corrosion performance
Zinc metallizing: sprayed zinc metal (99.5% pure) onto prepared surface, to a thickness of 100 µm for optimum corrosion performance.
Zinc rich paints usually offer the cheapest and fastest solution for reinforcing steel repair.
Handling, transport and storage
Due to the durability of the galvanized coating, no special handling or care is necessary when transporting galvanized reinforcing steel but some recommendations for transport include:
- The use of chains, wire ropes or cables to lift is acceptable
- Bundles should be lifted at multiple pick-up points
- The use of a spreader bar is recommended to prevent unnecessary bar-to-bar abrasion in longer bundles
- No special placement is necessary, although the reinforcing steel and mesh should be stacked to allow for drainage and air flow to avoid early wet storage stain
- As the coating is not sensitive to UV light it can be stored anywhere on site.
