I understand that the products of reinforcing steel corrosion occupy a greater volume than the original steel. This volume increase exerts tensile stresses in the concrete, causing it to spall. We're considering using galvanized reinforcing steel in which a zinc coating acts as a sacrificial anode, protecting the steel. However, I've heard that zinc also expands when it corrodes. Wouldn't this cause the same problem as steel? Also, what would happen if, rather than using galvanized rebar, you simply added finely divided zinc powder to the mix? Would the rebar be protected?
We have found that corrosion of zinc in a high-chloride concrete can produce zinc hydroxy chloride, which we calculate as occupying almost four times the volume of zinc. We have found that development of this corrosion product can crack concrete. William G. Hime, Principal Erlin, Hime Assc. Div. Wiss, Janney, Elstner Assc. Inc.