impresión

SALT CRUST - EFFLORESCENCE

Muestra

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


Causas de la patología

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).


Imagen de visu

SALT CRUST - EFFLORESCENCE: SALT CRUST - EFFLORESCENCE
Autor: CETEC-patrimoni

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


Imagen detalle / macro

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

Imagen Microscopía

SALT CRUST - EFFLORESCENCE: SALT CRUST - EFFLORESCENCE
SALT CRUST - EFFLORESCENCE: SALT CRUST - EFFLORESCENCE
Autor: CETEC-patrimoni
Aumentos: Figure 1. SEM-BSEI-image x100. Figure 2.- SEM-BSEI-image x2000
Descripción: 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

Patologías Asociadas

Flaking.

Sanding.

Alveolization.


Otros Análsis

XRD. Efflorescence of gypsum and hexaedrite.

Observaciones

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

Bibiliografía

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


Institución o Empresa

ESCRBCC