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  • 1880

    A German researcher Michaelis was granted a patent on his steam curing processes

  • 1889

    Czech Hoffman successfully tested and patented the method of “aerating” the concrete by carbon dioxide

  • 1914

    Americans Aylsworth and Dyer used aluminum powder and calcium hydroxide to attain porous cementitious mixture for which they also received a patent

  • 1920

    Swede Axel Eriksson made a serious next step towards developing modern AAC when he patented the methods of making aerated mix of limestone and ground slate (a so-called “lime formula”)

  • 1923

    The Breakthrough

    The real breakthrough in the masonry industry came in 1923 when same architect Axel Eriksson discovered that this moist foamed mass can easily handle pressurized steam curing process, also known as autoclaving. While applying for a patent two crucial conclusions were drawn:

    - the material hardened fast thanks to the autoclaving process
    - shrinkage was almost absent after steam curing compared to the normal air curing.

    Additionally, later it was also discovered that alternative materials, such as pulverized ash, could be used instead of lime/cement, allowing to economize on expensive raw material binder.

  • 1929

    Eriksson’s success immediately attracted a much needed commercial interest and in 1929 the first large scale manufacturing facility of these artificially-made crystalized stone blocks was launched in a factory “Yxhults Stenhuggeri Aktibolag“, Sweden under the name Yxhult. In 1940 the “Yxhult” name was changed to YTONG as this name was easier to pronounce.

  • 2014

    As of 2014, there are more than 3,000 AAC production facilities with an estimated production capacity of 450 million m3 per year of non-reinforced blocks. Mass production of blocks is also popular in Central and Eastern Europe and India while Japanese, Korean, Australian and Western European markets are focusing more and more on reinforced panels and high precision blocks.