Sorel cement
Sorel cement (also known as Sorel concrete ) is an acid-base cement developed in the 1850s / 1860s by the French Stanislas Sorel . An aqueous magnesium chloride solution acts as the acid , and magnesium oxide ( burnt magnesia , MgO) as the base , which is technically known as caustic burnt magnesite (KM) . Depending on the reactivity of the magnesium oxide used, the mixture will harden within minutes or hours:
5 MgO + MgCl 2 + 13 H 2 O → 5Mg (OH) 2 • MgCl 2 • 8H 2 O
The resulting compound is a magnesium oxychloride .
Magnesia cement combines well with organic, porous substances such as wood, cork and leather and preserves them.
use
Housing and Industry
Sorel cement is used for the production of industrial floors and - dry-to-use - grinding and polishing stones for the marble industry. The advantage is the rapid development of strength and the high final strength, the disadvantage is the fact that the chloride can be washed out of the set cement when exposed to water.
In the German-speaking area, such floor coverings are called magnesia or magnesite coverings. Compared to conventional cement-bound screeds , magnesia screed can also be laid over a large area without joints, as it does not shrink much when it sets.
A variant of the magnesite screeds are the floor coverings known as stone wood. In the post-war period in particular, they were used a lot in residential construction - but also for low-stress floors in the commercial sector. Considerable amounts of wood flour (sawdust) are added to the magnesite binder or Sorel cement as a filler. Stone wood floors are warm to the feet and comfortable to walk on, they have a certain elasticity.
A significant disadvantage of all magnesite coverings is their poor water resistance. When moistened, the binding agent swells and can loosen from the substrate over a large area. In addition - because of the chloride contained in the binder - contact with metals sensitive to corrosion must be avoided. Even stainless steel is usually not resistant to chloride.
The Austrian manufacturer Heraklith binds wood wool with Sorel cement for the production of lightweight boards (which are also made with conventional gray and white cement ).
Barriers in the salt mining nuclear waste storage facility
Sorel cement is used for flow barriers in the Asse mine . Mixing plants were built in their vicinity. Building materials made from ordinary cement are decomposed over time by water-soluble salts. Sorel concrete, on the other hand, is resistant to the locally occurring potash salts.
literature
- Alan D. Wilson, John W. Nicholson: Acid-base cements. Their biomedical and industrial applications. Cambridge University Press, Cambridge 1993, ISBN 0-521-37222-4 , (= Chemistry of solid state materials 3).
Individual evidence
- ↑ Archived copy ( Memento of the original dated November 7, 2011 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Dipl.-Ing. Bonar Marbun: Kinetics of the hydration of CaO and MgO , p. 9, dissertation, February 2006, Faculty of Natural and Material Sciences, Clausthal University of Technology
- ↑ Operation ( Memento from July 25, 2013 in the Internet Archive )
