Thermography investigation of Roman arcaelogical masonry

Among the advantages of infrared thermography (IRT) -rapid, non-destructive, real-time preliminary data interpretation, data visualisation as 2-D images– the fact that this is a noncontact technique is a particularly useful addition when the object of investigations is a historic or ancient structure, benefiting from high protection level, on which the application of invasive techniques for assessment purposes is strongly discouraged. On cultural heritage, even the contact between material surface and testing instrumentation might not be allowed, whilst the possibility of combining NDT with invasive or destructive methodologies for calibration purposes must be kept to a minimum. IRT tests have been carried out on masonry walls from a Roman house in Herculaneum, in Italy. Masonry elements present thick plaster from the superposition of original Roman plaster to modern plaster dated to the restoration interventions of 20th Century. The IR analysis aimed at investigating the state of bonding between plaster and its support, and the construction details that are not visible, being hidden under the finishing layer, such as the shape and layout of the masonry units. Example results from passive IR inspections are shown and the significance of outcome, in terms of acquired knowledge about the archaeological masonry structure, is discussed.