Galvanized rebar is standard steel reinforcing bar that has been coated with a protective layer of zinc, usually through a process called Hot-Dip Galvanizing (HDG).

Its primary purpose is to provide superior corrosion protection for concrete structures exposed to harsh environments, significantly extending their service life.

1. How It Works: The Dual-Layer Protection

Galvanized rebar protects concrete from structural failure (like "concrete cancer" or spalling) through two distinct mechanisms:

1. Barrier Protection: The zinc coating forms a physical, highly durable barrier that prevents moisture, oxygen, and chlorides (salts) from reaching the underlying steel.

2. Sacrificial Protection (Cathodic): If the coating is scratched or damaged during transport, bending, or concrete pouring, the surrounding zinc will actively corrode first to protect the exposed steel. Zinc is chemically more active than iron, so it sacrifices itself to save the steel core.

2. Key Benefits

High Chloride Tolerance

In standard black rebar, corrosion begins when chloride levels in the concrete reach a certain threshold. Galvanized rebar can withstand chloride concentrations 2 to 4 times higher than black steel before corrosion triggers. This makes it ideal for coastal or marine environments.

Mitigates "Concrete Cancer"

When standard rebar rusts, the volume of the rust expands up to 600%, creating immense internal pressure that cracks the surrounding concrete (spalling). Zinc corrosion products take up much less volume and actually migrate into the concrete matrix without causing harmful expansive pressure.

Excellent Coating Toughness

During the hot-dip process, the zinc metallurgically bonds with the steel, creating several alloy layers that are harder than the base steel itself. This makes it highly resistant to the rough handling, scraping, and stepping that occurs on a job site.

Galvanised Rebar