Modelling of the conservation state of gypsum-based plasters in the Real Alcazar of Seville

Abstract

Plasterworks are gypsum-based decorative elements characteristic of Muslim art, providing a relevant historical and patrimonial heritage. Its natural ageing, associated with the action of degradation agents led to the appearance of anomalies, requiring the adoption of adequate and regular maintenance strategies. The Real Alcazar of Seville (Spain), presents an extensive area of decorative plasters, and the establishment of a hierarchy of preventive conservation can be a very difficult task. In this study, a model to evaluate the overall degradation condition of plasterworks is proposed, based on a numerical index, called severity of degradation (Sw ), which contemplates: i) the area affected by the different anomalies that can occur; ii) their severity, through the adoption of various degradation levels; iii) and the relative importance of each anomaly. The evaluation of the degradation condition is performed through visual inspections and through the application of non-destructive tests and image analysis.