AAC life cycle: How long can autoclaved aerated concrete buildings be used

Due to its very good properties, autoclaved aerated concrete (AAC) is a very popular construction material which is a first choice as a masonry unit in a number of countries. Aerated concrete has been mass‐produced for almost 100 years. Experience and dozens of research programs prove it is a good and durable material, eco‐friendly on top of that. Unfortunately, in many countries, the history of AAC production is shorter. This research program tested different AAC blocks in various density classes, which were stored for many years in natural conditions and regularly tested for all properties. Furthermore, the research program included tests of AAC blocks from demolished buildings and blocks tested in climate chambers with CO₂ in the lab. The age of those buildings ranged from 25 to 60 years. The analysis of phase composition and microstructure in all samples allowed the research team to determine the moment when the C‐S‐H phase, mainly tobermorite, will become nearly 100% re‐carbonated. Those calculations can be used to determine the life span of buildings erected using autoclaved aerated concrete.