... used at a rate of 0.05%–0.08% by volume (depending on the pre-specified density). When AAC ... , the hydrogen escapes into the atmosphere and is replaced by air.When the forms are removed from the material, ... up to 80% of the volume of an AAC block is air. AAC's low density also accounts for its ... China, Bahrain, India, and Australia. AAC is increasingly used by developers, architects, and home builders.