Nothing that I read offered a solution. They implied that pre-carbonating gets over the problem of cracking of the concrete as it carbonates, but that isn't a serious issue. Corrosion of reinforcing steel can and does occur in uncracked concrete if the pH is not kept alkaline. The permeability of the concrete to air is ample to allow this. Subsequently cracking occurs because the corrosion products have a higher volume than the steel they replace. The cracking is a result of the corrosion, not the cause of it.