ABSTRACT
The Colegio Santo Domingo of Orihuela (Spain) suffers a rapid and severe damage due to salt crystallisation by rising damp. The exterior walls and columns show loss of material (scaling, granular disintegration and alveolization) and efflorescences and crusts (gypsum and halite). In the interior of the building, different precipitation sequences are observed in the vertical profile, where the more soluble salts are located at higher heights of walls and columns. SEM images reveal different conditions in the saturation degrees of minerals, ranging from isometric shapes to needle-like crystals. Single salts are halite, sylvite, gypsum, thenardite, epsomite and hexahydrate. Double salts (humberstonite and aphthitalite) show a near equilibrium crystal shape, which suggest they precipitate via incongruent reactions rather than a congruent precipitation. Water level variations in the building foundation may determine the dissolution of single salts and precipitation of the double ones.
