A major consideration is whether the aluminum will be embedded in the concrete, if it is, you may want to reconsider the choice of using aluminum, whether it is bolted, welded, or glued.
Concrete is an alkyd, which doesn't play well with aluminum.
Sodium hydroxide, also an alkyd, is used to deoxidize the surfaces of aluminum prior to welding. The problem is that if the aluminum is let in the sodium hydroxide too long, there is nothing to retrieve or to weld.
Best regards -Al