10. Long-Term and Sustainable Approach to Preserve Ancient Mosaic Heritage: The Case Study of Mosaic Pavement Located at the “Sanctuary of Pan,” Pnyka (Athens)

In the historical center of Athens, surviving mosaic pavements, dating back to the Roman times, can be found in several archeological sites. The awareness of their increasing damage has resulted in a great effort to preserve them. In this sense, this paper intends to propose an innovative and user-friendly procedure. This is based on nondestructive techniques investigation, which could be included in a long-term and sustainable approach to preserve the ancient mosaic heritage. As a case study, a mosaic pavement dated back to the Roman period, located on the ancient hill of Pnyka, was investigated by means of infrared thermography (IR thermo) and ground-penetrating radar (GPR) technique. Both techniques assessed the deterioration state and the conservation treatment previously applied on the aforementioned structure substrate. Moreover, samples from the substrate mortar were analyzed in the laboratory by means of advanced methods, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential thermal analysis-thermogravimetry (DTA-TG). The results derived from this study verify that nondestructive testing techniques are very suitable for the inspection of mosaic pavements, providing useful information concerned with the structural integrity of the mosaic, revealing, also, its preservation state. In addition, supplementary analysis of mortar samples aims to the characterization of the constituent materials and the better understanding of decay factors.