There are few manufacturers in the U.S.In a report written for UC–Davis (PDF), Stefan Schnitzler finds few disadvantages to AAC. AAC also has excellent soundproofing properties.It's a better insulator, with a steady-state R-value just a hair above R-1 as opposed to something more like R-0.2 (neither of these factors in thermal mass, which we'll get to later).
The resulting blocks are so full of bubbles that a block of the same size has about one-fifth the material required by regular concrete. The concrete is poured into molds, left to rise, and then "baked" in an autoclave, which uses steam and pressure to complete the chemical reactions and speed up the curing process significantly-completing in hours rather than weeks. (Your muffins are full of carbon dioxide bubbles, but AAC is full of hydrogen bubbles.) AAC is similar to other concrete types, except that it contains no aggregate sand or fly ash is included, with aluminum powder added to react with one of these ingredients and "leaven" the concrete, creating tiny bubbles just like baking soda does when it reacts with the buttermilk in your muffin batter.