(553a) Production of Autoclaved Cellular Concrete with Aluminum Salt Cake Residues

Aluminum is recycled through a smelting process. Salt of NaCl and KCl mixture was added during the smelting to seal the air from the aluminum melt and to help dissolving the surface aluminum oxide. After aluminum smelting, the salt cake is disposed. In this study, aluminum salt cake is processed to recover the salt and coarse aluminum particles. The residue powder is rich in aluminum oxide, but still containing a few percent of fine aluminum metal locked in the powder. Attempt is made to substitute the aluminum metal powder in the autoclaved cellular concrete production with the aluminum salt residue. Aluminum can react with water at high pH to generate hydrogen gas. This property has been utilized for the production of autoclaved cellular concrete, where aluminum powder is added to a mixture of cement, lime, water and sand developed to develop a foamed lightweight concrete structure. This material is lightweight and has good insulation property. However, the use of expensive aluminum powder has limited its broad applications. Results of this study indicated that this aluminum salt cake residue can generated a sufficient amount of H2 gas, and the product exhibits 50 pcf in density and 400 psi in strength. This research also indicate that when using 20 wt% cement can provided the most efficient value for the autoclave processing.