AAC — for autoclaved aerated concrete — is more air than concrete: 80 percent air, according to the Portland Cement Association (PCA). However, it’s also lightweight, easy to manufacture and, when reinforced with steel, strong enough to withstand earthquakes and hurricanes.
“It is an environmentally-friendly solution for future building problems and it is also an extremely efficient, specialty fabrication material,” said Mohamed Mahgoub, an assistant professor at the New Jersey Institute of Technology (NJIT).
Mahgoub is coordinator of the NJIT Concrete Industry Management program, which is one of only a few such programs across the US. His students this semester have been testing and analyzing AAC.
Developed by Johan Axel Eriksson, a Swedish architect and inventor, in the 1920s, AAC is made with finely ground sand, cement, quick lime, gypsum and water. Pumped into tanks as a slurry and kept constantly agitated, the mix is then blended with an agent like aluminum powder, which reacts with the slurry to create air bubbles that cause the material to expand. The result is a low-density — light enough to float in water — strong, highly insulating and sound-blocking construction material that can be shaped and cut like wood.
While the manufacture of cement produces a large amount of carbon emissions, AAC is more environmentally friendly than traditional types of concrete (cement mixed with aggregate materials) because it contains “less raw material per volume than many other building products,” according to the PCA.