Use of gasification residues in aerated autoclaved concrete

Two fine-grained residues produced by gasification of wastes were tested for their suitability in aerated autoclaved concrete (AAC). AAC typically has additional aluminium powder added to the raw ingredients to facilitate the formation of small gas bubbles which provide a low-density product. Both gasification residues had high amounts of metallic aluminium and thus were well suited for this application. Studies were conducted to determine whether the residue addition would eliminate the need for the extra aluminium powder for creating air voids. Simultaneously, the residues replaced some of the aggregate ground in the process, thus enabling savings in energy consumption. Initial laboratory tests determined how much residue could be added and what type of concrete mixture proportioning was needed. Multiple properties were tested on AAC with 10% residue addition, with and without the additional aluminium powder. After laboratory investigations, full-scale tests were done at the Siporex AAC factory in Finland. These tests revealed that the residues offer a promising resource for economic production of AAC without detrimental effects to the final products.