GI?

No worthwhile bolts are made from simple iron, galvanized or otherwise.

Various grades of steel bolts may be cadmium-plated, electrogalvanized, or hot-dip galvanized. HDG usually has the best corrosion resistance, but the thicker layer of zinc can be rough, and if too thick can make the bolt too tight to fit into nuts or tapped holes.

(GI pipe is another antiquated misnomer.)

I agree with Tornado, but if the specification requires"GI" bolts, you can't use cad plated bolts without a deviation authorization.

Since you are asking total strangers for advice, you may not be qualified for this job.

You'll need authorization from an engineer to proceed.

In this country, cadmium is restricted due to it's toxicity.

I think that is true in most western countries.......

We are not the right people to ask about Cadmium and the poisonous chemicals used to plate it!!! (Cyanide if I remember correctly!)