best protection for HDG steel welds

[MSEdesigns]

We had some problems and now have to weld the hot dip galvanized steel reinforcement used in a Segmental Retaining Wall. These reinforcements are made of steel rods about 5/8" diameter down to 3/8". They will be buried in granular material, probably 3/4" aggregate down to a A-1-a material as classified by AASHTO. As part of the reinforcement design, sacrificial steel has been added to be sure we have enough steel there after 75 or 100 yr which is the design life of these structures. Now we have to field weld these rods, so we need to know which weld method will be better and what type of protection is better to protect the welded area? The project is in the caribbean where we have mild climate but very humid (around 70 inch rainfall per year).
Thanks for your help.

 

[Metalguy]

I suspect you may have problems long before 75 years! The reason rebar in concrete lasts so long is because "good" concrete keeps the steel at a high pH, ~10.5 or 11. Corrosion rate can be fairly low at that high a pH, depending on some other factors. But you don't have concrete to protect the steel, only zinc. The zinc will last for some years, but it gradually becomes ZnO and disappears.

Under your conditions, I would take a good look at some kind of epoxy coating.