History
The material was perfected in the mid-1920s by Dr. Johan Axel Eriksson, an architect working with Professor Henrik Kreüger at the Royal Institute of Technology. It went into production in Sweden in 1929 in a factory in Hällabrottet and became very popular. In the 1940s, the trade mark Ytong was introduced, but it was often referred to as "blue concrete" in Sweden due to its blueish tinge. This version of Ytong was produced from alum shale, whose combustible carbon content made it beneficial to use in the production process. The competing concrete brand Siporex produced in Tuzla, Bosnia, used other raw materials. "Ytong" acquired Siporex and today produces "Siporex" under "Ytong" brand in Tuzla, Bosnia factory. However, the slate deposits used for Ytong also contain uranium, which makes the material give off radioactive radon gas to 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. Ytong produced after 1975 has used raw materials without the uranium content.
Read more about this topic: Autoclaved Aerated Concrete
Famous quotes containing the word history:
“A great proportion of the inhabitants of the Cape are always thus abroad about their teaming on some ocean highway or other, and the history of one of their ordinary trips would cast the Argonautic expedition into the shade.”
—Henry David Thoreau (1817–1862)
“The visual is sorely undervalued in modern scholarship. Art history has attained only a fraction of the conceptual sophistication of literary criticism.... Drunk with self-love, criticism has hugely overestimated the centrality of language to western culture. It has failed to see the electrifying sign language of images.”
—Camille Paglia (b. 1947)