Autoclaved aerated concrete

Autoclaved aerated concrete (AAC) is a lightweight, precast, foam concrete building material suitable for producing concrete masonry unit (CMU) like blocks. Composed of quartz sand, calcined gypsum, lime, cement, water and aluminum powder, AAC products are cured under heat and pressure in an autoclave. Invented in the mid-1920s, AAC simultaneously provides structure, insulation, and fire- and mold-resistance. Forms include blocks, wall panels, floor and roof panels, cladding (façade) panels and lintels. Autoclaved aerated concrete (AAC) is a lightweight, precast, foam concrete building material suitable for producing concrete masonry unit (CMU) like blocks. Composed of quartz sand, calcined gypsum, lime, cement, water and aluminum powder, AAC products are cured under heat and pressure in an autoclave. Invented in the mid-1920s, AAC simultaneously provides structure, insulation, and fire- and mold-resistance. Forms include blocks, wall panels, floor and roof panels, cladding (façade) panels and lintels. AAC products may be used for both interior and exterior construction, and may be painted or coated with a stucco or plaster compound to guard against the elements, or covered with siding materials such as veneer brick or vinyl siding. In addition to their quick and easy installation, ACC materials can be routed, sanded, or cut to size on site using standard power tools with carbon steel cutters. Other names for the product include autoclaved cellular concrete (ACC), autoclaved lightweight concrete (ALC), autoclaved concrete, cellular concrete, porous concrete, Aircrete, Thermalite, Hebel Block, Starken, and Ytong AAC was perfected in the mid-1920s by the Swedish architect and inventor Dr. Johan Axel Eriksson, working with Professor Henrik Kreüger 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 Ånghärdade Gasbetong' later became the first registered building materials brand in the world: Ytong. Another brand “Siporex” was established in Sweden in 1939 and presently licences 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. Originally Ytong autoclaved aerated concrete in Sweden was produced with alum shale, whose combustible carbon content was beneficial in the production process. Unfortunately, the slate deposits used for Ytong in Sweden also contain a very low level of natural uranium, which makes the material give off radioactive radon gas in the building. In 1972, the Swedish Radiation Safety Authority pointed out the unsuitability of a radon-emitting construction material, and the use of alum slate in the production of Ytong ceased in 1975. By using new formulations, containing only quartz sand, calcined gypsum, lime (mineral), cement, water and aluminum powder, Ytong produced a new type of aerated concrete which no longer contains alum slate and thus has eliminated the problem of radon exposure from this raw material. The production of this white autoclaved aerated concrete is now state of the art and similar formulations are used by all producers around the world. In 1978 The Swedish team of Siporex Sweden opened the Siporex Factory in the Kingdom of Saudi Arabia - the 'Lightweight Construction Company - Siporex - LCC SIPOREX' which have supplied the Middle-East and Africa and Japan by most of its need. The LCC SIPOREX FACTORY has operated for more than 40 years. Today aerated concrete is produced by many companies, particularly in Europe and Asia. There is some production in the Americas and in Africa, there is one plant in Egypt. AAC production in Europe has slowed down considerably, but the industry is growing rapidly in Asia due to strong demand in housing and commercial space. China is now the largest aircrete market in the world with several hundred factories. China, Central Asia, India, and the Middle-East are the biggest in terms of AAC manufacturing and consumption.