Burn up

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Under firing in construction is defined as the lack of hardened mineral building materials by the absence or premature withdrawal of water during solidification . Coating materials such as paints and plasters are usually affected, which then sand, chalk off and are not sufficiently pressure and abrasion resistant. On the other hand, cracking or peeling is usually not to be expected, especially if lime is used as a binding agent. In the case of highly absorbent masonry stones and very warm and dry weather, it is also conceivable to burn the masonry mortar .

Due to insufficient added water , highly absorbent substrates, exposure to sunlight, wind or excessively high temperatures, plasters and mineral paints can dry up without their hydration being completed. During the hardening process, the building materials cannot bind enough water as crystal water to achieve the intended strength.

To prevent burning

  • absorbent surfaces are pre-wetted, for example by spraying with a mason's brush or a water hose
  • Strongly absorbent substrates such as soft-fired bricks and clay building walls are intensively pre-wetted several times until the superficial moisture is no longer immediately absorbed
  • absorbent bricks are immersed (briefly) in water before moving
  • Alternatively to pre-wetting, the absorbency can be reduced with a primer ("Aufbrennsperre" or " Tiefgrund "); this is particularly recommended for substrates containing gypsum, as these can be damaged by the necessary, intensive pre-wetting
  • the surfaces can be hung immediately after completion to protect against solar radiation
  • the surfaces can be hung with wet sheets immediately after completion or, if necessary, moistened.

In the case of dense surfaces such as concrete or cement plaster, pre-wetting is usually not necessary. On the contrary, plaster adhesion can be hindered if there is a film of water on dense surfaces that is not absorbed by them within a reasonable period of time.

literature

  • Kurt Schönburg: Mineralfarbenentechnik am Bauwerk , Beuth, Berlin 2013, p. 142. ISBN 9783410231912
  • Alexander Reichel, Anette Hochberg, Christine Köpfe: Plasters, paints, coatings , de Gruyter, Berlin 2004, p. 53. ISBN 9783955530327

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