Ancient mortars: from diagnostic investigations to FAIR modeling of scientific data

This thesis concerns the study of mortars used in archaeological contexts located in areas characterized by high seismicity, specifically, the well-known sites of Pompeii and Hierapolis of Phrygia, as well as Carsulae and Narni in Umbria. The research focused on the diachronic evolution of raw material selection and production techniques for mortar-based materials, while also identifying the factors responsible for their remarkable durability. To this end, the mortars were characterized through a multi-analytical approach that included mineralogical, petrographic, and geochemical analyses, complemented by advanced investigative techniques capable of examining materials at the micrometric scale, such as Fourier-transform infrared spectroscopy with a Focal Plane Array detector (FPA-FTIR) and synchrotron radiation X-ray diffraction (SR-XRD). At Pompeii, the study focused on mortar-based materials mainly collected from public buildings in the Forum Grande area. The archaeologically dated samples revealed morphometric and morphological differences in binders and aggregates clearly attributable to distinct construction phases, particularly evident in materials used after the devastating earthquake of 62 CE, thereby confirming the previously proposed chronological attributions. At Hierapolis, analyses of samples from public buildings investigated the historical evolution of mortar production technologies and raw material selection over a period from the Roman to the Middle Byzantine era, highlighting attempts to adapt construction techniques to repeated seismic events. In Narni, the study of the “Bridge of Augustus” confirmed the extraordinary Roman engineering expertise in producing custom-made mortars designed to achieve maximum performance in accordance with specific structural requirements. Similarly, at Carsulae, analyses of the Arch of San Damiano and a nearby cistern once again demonstrated the Roman builders ability to adapt materials to their intended function. Notably, the analysis of the raw materials used in the two structures at Carsulae and in the Bridge of Augustus at Narni revealed the use of silicified limestones for binder production, resulting in mortars with excellent hydraulic properties even without the addition of reactive aggregates, a characteristic that deserves further investigation. The use of pozzolanic aggregates in structures in direct contact with water suggests that the Romans were unaware of the hydraulic capabilities naturally derived from the use of local materials. As for the results of my analyses on the materials from Hierapolis, their integration into the DataSpace platform has begun through the MORTARS project. All the data I have produced will thus be shared with the interested scientific community, which, by relying on already processed analyses, will be able to make use of them to accelerate its own research.