Autoclaved aerated concrete (AAC), also known as autoclaved lightweight concrete (ALC), autoclaved concrete, cellular concrete, porous concrete, Aircrete, Hebel Block, and Ytong is a lightweight, precast, foam concrete building material invented in the mid-1920s that simultaneously provides structure, insulation, and fire- and mold-resistance. AAC products include blocks, wall panels, floor and roof panels, cladding (facade) panels and lintels.
AAC Blocks are a unique and excellent type of building material due to its super heat, fire, rot resistance and remarkable sound proofing qualities. AAC blocks are lightweight and offer ultimate workability, flexibility and durability. Its main ingredients include sand, water, lime and cement. The chemical reaction due to the aluminum paste provides AAC its distinct porous structure, lightness, and insulation properties, a completely different product compared to other lightweight concrete materials
AAC has been successfully used in Europe since the 1920s and other parts of the world since the 50s and 60s. In Europe, there are today more than 100 production sites in 18 countries producing an estimated 20 million m3 of AAC per year
AAC was perfected in the mid-1920s by the Swedish architect and inventor Dr. Johan Axel Eriksson, working with Professor Henrik Kreuger at the Royal Institute of Technology. The process was patented in 1924. In 1929, production started in Sweden at the city of Yxhult. From "Yxhults Anghardade Gasbetong" came the first registered building materials brand in the world: Ytong. Another brand "Siporex" was established in Sweden in 1939 and presently licenses and owns plants in 35 locations around the world. The second major international cellular concrete Hebel brand goes back to company founder and technicians Josef Hebel from Memmingen. In 1943, the first Hebel-plant was opened in Germany.
AAC is a highly thermally insulating concrete-based material used for both internal and external construction. Besides AAC's insulating capability, one of its advantages in construction is its quick and easy installation, because the material can be routed, sanded, or cut to size on site using standard carbon steel power tools.