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SALT CRUST - EFFLORESCENCE
SALT CRUST - EFFLORESCENCE

Mostra

Church of the Monestir d’Aviganya.  Ntra. Sra. del Remei Chapell. LLeida. Spain.


Causes de la patologia

Alkaline salts (potassium and sodium sulphates) from the cement used in the repairs of the Church roof have leaked in the walls of the building. These salts have also reacted with the components of the stone, especially with the dolomite mineral, generating new salts of different composition, magnesium sulphates (hexaedrite). The two processes have combined to accelerate the process of alteration (synergic effect).


Imatge de visu

Autor: CETEC-patrimoni

Descripció: Efflorescence and salt crust on stone ashlars associated with damp patches due to leaks from the roof.


Imatge detalli / macro

SALT CRUST - EFFLORESCENCE
Autor: CETEC-patrimoni
Augments: 20 x
Descripció: Crystal aggregates of white colour and irregular size and shape. They present different crystalline forms: needle-like, rounded, and fibrous.

Imatge Microscòpia

SALT CRUST - EFFLORESCENCE
SALT CRUST - EFFLORESCENCE
Autor: CETEC-patrimoni
Augments: Figure 1. SEM-BSEI-image x100. Figure 2.- SEM-BSEI-image x2000
Descripció: Figure 1. There are two types of crystalline aggregates. The first one is a needle-like or lenticular gypsum tablets. The second one is a crystalline aggregate with crystals rounded or globular composed of magnesium sulphate.
Figure 2. Dolomite crystal altered by chemical reaction with the salts of cement, generating new magnesium salts

Patologies Associades

Flaking.

Sanding.

Alveolization.


Altres Anàlisis

XRD. Efflorescence of gypsum and hexaedrite.

Observacions

Efflorescence of gypsum and hexaedrite showing that dolomite crystal has been altered by chemical reaction with the cement salts, generating new magnesium salts.

Bibliografia

CARNER, E.N.; DERMICI, S; TURKMENOGLOU, A.G. Deterioration of dolomite by soluble salts in Divrigi Great Mosque –Turkey. V Th. Int. Congrees on deterioration on conservation of stone. Lausanne 1985.

 

MADRUGA, F.; SAAVEDRA, J.; MARTIN PATINO, M.T.  Eflorescencias y costras sobre areniscas de

Villamayor. Ensayos de laboratorio. Materiales de Construcción, vol 44, nº 234. 1994. doi:10.3989/mc.1994.v44.i234.587

Autor

Jose Luis Prada Pérez. prada43@wanadoo.es

Geologo


Institució o Empresa

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