Restoration mortar

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Restoration mortars (also known as application or stone substitute ) are used by stonemasons to repair defects in historical buildings made of natural stone . Larger flaws of more than 100 cm² are repaired with so-called crossings made of natural stone , which corresponds to the original stone or this largely.

use

Restoration mortars are applied in accordance with DIN 18332 for natural stone work on imperfections up to a maximum size of 100 cm². A distinction is made between mineral-bound, synthetic resin-bound or silica gel-bound applications. The flaw in a building is worked out by hand with appropriate stone cutting tools, only morbid substance is removed and care is taken that there is minimal loss of substance. The application itself is mixed and applied earth-moist and optically adapted to the adjoining stone surfaces .

composition

  • Mineral- bound restoration mortars consist of aggregates such as sand and paint particles with the binding agents building lime and cement , which can be modified with building resins. When it comes to mineral masses, a distinction is made between application mortar and restoration mortar. The application masses, which are called the core structure or base mass, are not color-matched and are covered by the color-modified restoration mortar for about 3 centimeters as the top finish. The visible stone surface is structurally adapted to the stone surfaces surrounding it and, if necessary, given a final colored glaze, if this is necessary. These mortars can be purchased from the stonemasons on the construction site in terms of the natural stone surrounding it. These stone substitutes are used primarily for damaged masonry or for profiled stone . These mortars are mixed with mixing water on the construction site and are permeable to water vapor.
  • Resin -bonded Restoration reach much higher adhesive tensile strength and are mostly precious stone in artistic and art-historical sculptures and stone Bauzier used. The mortar is two-component and consists of quartz grains and color pigments to which synthetic resin, usually epoxy resin or acrylic resin , is added on site. It should be noted that these mortars can form a water-impermeable seal when applied over 8 mm thick.
  • Silica gel- bonded restoration mortars are made from the aggregates quartz powder and quartz sand and for coloring with ground sandstone. They are mixed in an earth-moist state with the addition of silicic acid ester. A silica gel is formed during the setting process. These restoration mortars are permeable to water vapor.

literature

  • Michael Berude: Stone restoration and monument preservation . In: Bildungszentrum für das Steinmetz- und Bildhauerhandwerk (Ed.), Steinmetzpraxis, The manual for daily work with natural stone, p. 428 ff. 2nd revised edition, Ulm 1994. ISBN 3-87188-138-4 .
  • Andreas Boué (ed.): Stone addition. Mortar for stone restoration . 1st workshop of the Institut für Bauchemie Leipzig eV Kloster Nimbschen June 26th and 27th 1998. Fraunhofer IRB Verlag, Stuttgart 1999. ISBN 3-8167-4708-6 .