Concrete attacks aluminum due to its high pH. Especially true for fresh concrete, as when embedding. The aluminum should be coated with something caustic-resistant; anodizing will not work. I don't know the structural codes, but here are a few threads from 2 years ago:
Concrete attack of aluminum.
Thread592-77698
Aluminum column base plates
thread507-77669
Dangerous Corrosion of Embedded Aluminum Posts in Hi-Rises [Florida]
