El empleo del yeso tradicional de Albarracín en las labores de consolidación de estructuras en el castillo de Ayyub de Calatayud (Zaragoza)

Resumen

The Castillo Mayor, also called Castillo de Ayyub, could be the citadel of the fortified Islamic city of Calatayud. The first reliable records of the city date back to the ninth century and, since then, the fortification has been continually transformed to maintain its defensive use until the beginning of the last century. The uniqueness of its structures, which lies in the use as building material of the gypsum extracted from the mountain on which the castle is founded, does not lead to a precise chronology. Gypsum is used both in rammed earth as in ordinary masonry and it appears continuously from the oldest structures to the modifications carried out in the twentieth century. The use of gypsum on the outside of the buildings is restricted in the Iberian peninsula to a small geographical area, due to its high hygroscopicity, that makes the material unfit for its use in locations exposed to the action of water. This article describes the use of traditional gypsum of Albarracín as binder as well as a finishing material, in three campaigns of conservation and reintegration of its structures.