Galvanised steel reinforcement bars or galvanized rebars are steel rebars that have been galvanized with a coating of Zinc for making them more corrosion-resistant and durable.
Simple steel rebars have to rely only on protection from the concrete surrounding them. But, concrete is not impenetrable - it cannot stop corrosive elements such as chloride salts from coming in contact with the steel.
The zinc coating on the rebar acts as a protective layer by preventing corrosive elements present in the concrete from reacting with the steel and oxidizing it. In particular, galvanized steel has shown great resistance against chloride salt attacks and concrete carbonation.
Not only does zinc offer protection to the steel in this manner, it also provides cathodic protection to the steel as zinc corrodes preferentially when in contact with unprotected steel. This means that in the case that there are minor coating discontinuities on the rebar, the bare steel will be given protection by the zinc that surrounds it.
Also, the alloy layers are stronger than the pure steel core, which makes them capable of resisting abrasion and rough handling. Thus, the steel core remains unharmed when rebars are galvanized properly. The use of galvanized reinforcement steel bars makes the construction more durable.
While most manufacturers use the hot dip galvanizing process for zinc coating the steel bars, Madhav KRG Group uses the Continuous Galvanizing Rebars (CGR) technology which ensures the superior quality of the bars. In this process, the zinc is metallurgically bonded to the steel. As opposed to paints and epoxy coatings which can be removed relatively easily from the surface of steel, the steel and zinc come together and mix in a manner that they cannot be separated easily. This makes galvanizing a more reliable and durable method of coating and increases the life of the rebar without adding the need for regular maintenance.
When molten zinc and steel come in contact and react, layers of iron-zinc alloys (Eta, Zeta, Delta, Gamma) are formed which act as a coating for the steel rebar. On the inside, the coating is a mix of steel and zinc, but the outer surface of the coating is pure Zinc. Even if the outer layer corrodes, the inner core of steel will remain unaffected.
Thus, galvanizing increases the life of concrete structures and brings down their maintenance costs.
The Madhav KRG Group is one of the top producers of steel and steel-based products in India, and one of their chief products is Galvanized Reinforcement Steel Bars. Madhav Group’s galvanized rebars have dual protection layering created by zinc coating and passivation. However, this additional protection does not affect their bendability or weldability, which is the same as normal, uncoated rebars. Each rebar is thoroughly tested for quality before being delivered to the consumer. Madhav KRG Group galvanized rebars are available in HDPE Micro (60-80 kg) & Macro bundles (upto 2 tons).