Stone wood (covering)

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Stone wood (also magnesite screed or magnesia screed ) is a seamless screed and floor covering according to DIN 272 made of magnesia (MgO) or Sorel cement and organic or mineral fillers.

Originally, natural fibers were used as fillers in the stone wood developed in the 19th century . Due to its inexpensive production, the cement-like mass has been used in the construction sector since the beginning of the 20th century in sheet form under a variety of trade names ( xylolite , papyrolite , linolite , Dresden, etc.).

In contrast to stone wood , wood-concrete describes a mixture of lime and cement-containing binders and coarser wood chips , which is mainly used to manufacture bricks , wall elements and weatherproof components for outdoor use.

Development, composition and properties

In 1867, the French physicist Stanislas Sorel discovered that magnesia ( magnesium oxide ) solidified together with a magnesium chloride solution to form a cement-like mass. He recognized the practical possibilities of the new material and registered it as a patent at the K. and K. Patent Offices .

The usual mixing ratio of this material, named after its discoverer, Sorel cement , is 2.5-3.5 parts of magnesia (MgO) to one part of magnesium chloride (MgCl 2 ). From this mass and aggregates , coverings or slabs of various thicknesses can be produced. If the surcharge consists mainly of wood flour and fine wood chips , it is stone wood or hard stone wood (mixture 1: 2 to 1: 4). Instead of wood particles, crushed cork , paper or other organic or inorganic substances can also be added, with which the final properties can be varied.

Stone wood is warm to the feet, moisture balancing and pressure resistant. The compressive strength is given as up to 225 kp per cm². The material can be colored easily.

Due to the moisture sensitivity ( moisture stress class AO2) should be in bathrooms and other wet rooms a seal be provided. The equilibrium moisture content is 4–8%. Before a floor covering is applied, the moisture content must have fallen to 6–8% ( CM measurement ). Stone wood is classified as flame retardant . A fire resistance class of F-60B highly fire-retardant can be achieved. Stone wood has a higher conductivity than other screeds, which prevents static charging , especially with fair-faced screed . Footfall sound-absorbing , floating screed needs a thickness of 35 mm, heated screed can be made from 32 mm and composite screed from 20 mm. The density of stone wood is around 1200 kg / m³ compared to 2200 kg / m³ for most other screeds. The thermal conductivity of stone wood screed is 0.40 W / mK ( mastic asphalt 0.70 W / mK, calcium sulphate screed 1.20 W / mK, cement screed 1.40 W / mK). The internal attenuation with a loss factor µ of 0.03 for stone wood screed is favorable for air and footfall sound insulation (calcium sulphate screed 0.006, cement screed 0.006). The composition of stone wood has a wood preservative effect .

application

Stone wood is processed in a similar way to screed and, due to its properties, is used for highly stressed floors in kitchens and hallways as well as in workshops as industrial floors. Table tops and wall coverings have also been made from this material.

The architects of the Bauhaus worked with this economically favorable material in the 1920s and 1930s. For example, the floors in the Bauhaus Dessau were made of stone wood. Another well-known building with a stone floor is a baking factory in Berlin-Spandau built by the Taut & Hoffmann office . The Hans-Sachs-Haus , which opened in Gelsenkirchen in 1927, had around 6500 m² of stone flooring until it was completely redesigned.

Due to the growing interest in ecologically acceptable building materials, even today producers of stone wood coverings can assert themselves on the market after the further development of the composition of this product.

processing

Stone wood can be processed from 5 ° C. Higher temperatures up to a maximum of 25 ° C accelerate the setting, while high humidity delays the evaporation of the mixing water and the setting.

hazards

Stone wood installed in the post-war period may contain asbestos and then fall within the scope of the Ordinance on Hazardous Substances . An intact stone wood screed does not pose a risk. Drilling and other damage must, however, be avoided. Asbestos-containing stone wood screeds may only be removed by specialist companies with a certificate of competence and require extensive protective measures. Asbestos-containing stone wood screed is to be disposed of as waste that requires special monitoring ( hazardous waste ).

literature

  • Meyer's New Lexicon in eight volumes, Bibliographisches Institut Leipzig 1964, Volume 7 (Steinholz)

Individual evidence

  1. a b c Technical data sheet Steinholztechnik , Schubert Fußböden GmbH, Bad Vilbel
  2. R. Krippner: Dissertation 2004, TU Munich p. 29ff ( Memento of the original from December 9, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (accessed on April 29, 2014) @1@ 2Template: Webachiv / IABot / www.energielösungen-sanieren.org
  3. Zentralblatt der Bauverwaltung, 53 (1933), Issue 5, pp. 49-58: Large bakery plant in Berlin-Spandau
  4. Linolith stone flooring, sales brochure of a Swiss company (accessed on October 8, 2017)
  5. Guide "Healthy modernizing" (PDF; 3.6 MB), p. 54