A sacrificial coating for rebar may be the solution for a perplexing concrete repair problem--recurrence of corrosion after the repair is made. Zinc-rich epoxy resin protects rebar in the repair zone and in surrounding concrete. The zinc coating allows electrical contact between the bar and the active zinc. Zinc then acts as a sacrificial anode, protecting the steel.
First, remove all the cracked and spalled concrete, making sure to expose the full circumference of all bars. Then clean the exposed bars to remove corrosion deposits. Next, use a brush to apply the zinc-rich epoxy primer to the exposed steel. The protective value of the coating is proportional to its thickness. Dampen the concrete substrate with water and prime it with a cementitious slurry. Scrub the slurry into the substrate with a mason's brush and apply the repair mortar before the slurry dries. As a final step, apply a penetrating breathable sealer that will keep out water and chlorides.