Trass (rock)

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Trass (old spelling: Trass ) is the name for a natural pozzolan that is used as an additive in certain cements . It consists mainly of silicon and aluminum compounds .

origin

Rhenish route, pending in the Wolfsschlucht near Kell

When a meteorite hit what is now Nördlinger Ries , rock metamorphosis resulted in Bayerischer Trass, Ries-Trass or Suevit .

Rheinischer Trass is a volcanic tuff that was created when the Laacher See volcano erupted in the eastern Eifel and is found in the Brohl valley and the Nettetal.

A converted volcanite , which mainly consists of opal and alunite, is called Austrian trass or Gossendorfite . It was extracted from the Gossendorf quarry in Gossendorf near Feldbach, which was shut down in 2008. Based on this occurrence, the Steirische Montanwerke AG (today w & p / Baumit ) developed the trassit as a binding agent (a trass-lime finished plaster ).

use

The Kaiserhalle made of trass concrete in Burgbrohl

Trass is latently hydraulic and is used as a mortar with the addition of water and binding agents , cement and / or building lime and aggregates . Trass without the addition of binders does not harden.

Trass cement is an outdated term that is still used today for the new European cement classes such as Portland composite cement , pozzolan cement and composite cement . As an aggregate, trass makes mortar largely watertight. It is used, for example, for lining water basins, for laying and grouting natural stone and slabs, and as mortar and joint mortar for stone restoration work. A special trass mortar is used for the renovation of masonry contaminated with ettringite .

Another important advantage of the trass mortars is that when they are used, there is significantly less efflorescence on natural stone than with pure Portland cements, which are unsuitable for natural stone. Trass combines as far as possible with the hydrated lime, calcium hydroxide, which is split off during cement stone formation. If hydrated lime comes to the surface, it combines with the CO 2 contained in the atmosphere to form lime and shows up in the form of efflorescence. The formation of efflorescence due to other causes such as saltpetre are not prevented by adding a trass. Furthermore, the alkalinity of the mortar is not significantly reduced.

In exhaust gas cleaning , trass from the Nördlinger Ries is used as an adsorbent to remove odorous substances by means of adsorption . Compared to other adsorbents, trass has the advantage that it can be used at higher temperatures. While the application limit of activated carbon and activated coke is 180 ° C each, trass can be heated up to temperatures of 300 ° C.

standardization

Cements with trass are standardized according to CEM II (Portland composite cement), CEM IV (pozzolan cement), CEM V (composite cement). The properties for use in cements were previously standardized in DIN 1164, requirements and tests in DIN 51043. The line covered by the DIN 51043 standard is a pozzolanic tuff . It mainly consists of silicon dioxide ( silicic acid ) and aluminum oxide (alumina). Other components are oxides of alkali and alkaline earth metals .

See also

Web links

Individual evidence

  1. ↑ Duden. The German spelling. 22nd edition. Volume 1, Bibliographisches Institut (Dudenverlag), Mannheim / Vienna / Zurich 2000, ISBN 3-411-04012-2 , p. 976.
  2. ↑ Hans-Ulrich Schmincke: Vulcanism . Primus-Verlag, Darmstadt 2010, ISBN 978-3-89678-690-6 , p. 156.
  3. ↑ OENORM G 1046-8: 1985-09 Terms of the deposit science of stones, earths and industrial minerals ; Trass
  4. ^ The dismantling of the Gossendorf line was stopped in 2008. New life in the quarry. Kleine Zeitung , January 26, 2008, archived from the original on April 28, 2014 . ;.
  5. ↑ Use and origin of Trass , accessed on November 16, 2012.
  6. ↑ H. Kremser: Use of Trass in the Building Industry , Building Industry, Vol. 56, No. 24, 1976, ISSN  0005-6634 , pp. 25-29.
  7. ↑ Helmut Klaas & Erich Schulz: Damage to external walls made of brick and limestone - facing masonry , damage-free construction, vol. 13, 2nd edition 2002, Fraunhofer IRB Verlag, ISBN 9783816761143 , p. 43.
  8. ↑ VDI 3674: 2013-04 Flue gas cleaning by adsorption - process gas and flue gas cleaning . Beuth Verlag, Berlin, p. 26.
  9. ↑ Nethe, L.-P .: The importance of additives in the flue gas cleaning of thermal processes . VDI Bildungswerk 43-59-14, Munich 2002.
  10. ↑ a b c DIN 51043: 1979-08 Traß - Requirements, testing . Beuth Verlag, Berlin, p. 1.