Future structures, especially those to be re-built in storm-ravaged areas like Long Island and Atlantic City, could be made stronger and more disaster-resistant by using a material known as AAC.
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.
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Comments
Is there an application to recycle existing plaster on-site?
It is good to see AAC being talked about as solution to safe housing and construction need in disaster prone area. More than that it is high quality solution to housing and construction per se everywhere where fly-ash is available. I have done a study, which indicates that there scope for 1000 or more AAC plants of average capacity of 150000 cum per year being set up in India alone. However, there is need to work on following areas; Promoting and establishing AAC plain blocks of 800 kg cum or slightly more with compressive strength of 70 kg cm sq. or more as roofs and floors anchored on concrete girders. Promoting use of blocks of compressive strength of 50,60,70 kg cm sq in load bearing construction of 1 to 1+3 storey height buildings. Any industry interested in relocating it's plant and enter AAC business in India may contact me for comprehensive business development consultancy services. A.K.Chatterjee AD/118-D, Shalimar Bagh, Delhi-INDIA. PIN 91-110088. Phones: 91-011-27480498/42233622 Mobile: 09811441150 E-Mail; ashim10c@gmail.com
Excellent summary of the AAC's enormous advantages over other building materials. It is incredible that the U.S. lags far behind the rest of the world with an annual sales volume of $24 billion. To expand on the point about production, cement not only has a high carbon footprint, but is also one of the largest sources of highly toxic Mercury emissions in the country. Production of AAC does not produce any toxic substances and effluent consists of water than can go straight into waste-water systems. Its carbon impact is limited to the kind of fuel used to generate heat for the curing process, typically natural gas. Over the past several years, what limited production there was has been reduced. However, in the first quarter of 2013, a modern facility will open in South Carolina and be able to service markets up and down the Eastern Seaboard. Potentially good news for areas devastated by Hurricane Sandy. David Wisowaty Fenimore Partners, LLC