Archeologia e archeometria delle miscele leganti di Aquileia romana e tardoantica (II sec. a.C. - VI sec. d.C.)

The book “Archeologia e archeometria delle miscele leganti di Aquileia romana e tardoantica (II sec. a.C. – VI sec. d.C.)” presents the findings of an extensive research project focused on the analysis of the com- positional characteristics and properties of mortar-based materials used in the ancient town of Aquileia, located in Friuli Venezia Giulia, Northern Italy, from the Roman era to the early Middle Ages. Over 370 samples were collected from structures and buildings across various sectors of the ancient city. Sampling primarily targeted contexts in Aquileia currently under annual archaeological investigation by the Universities of Padova, Venice Ca’ Foscari, Verona and Udine. This dataset was extended by additional samples selected from wall plaster fragments, mostly recovered from secondary deposits during past and recent excavations and currently stored in the National Archaeological Museum of Aquileia or in univer- sity laboratories. The mortar and concrete samples were characterized using a multi-analytical approach, which included petrographic analysis using Optical Microscopy of thin sections (OM), mineralogical analysis using X-ray Powder Diffraction (XRPD), and microchemical investigations using Scanning Electron Microscopy with associated Energy Dispersive X-ray Spectroscopy (SEM-EDS). In specific cases, additional techniques such as X-ray Fluorescence (XRF) and Raman Spectroscopy were employed. Principal component analysis (PCA) and other statistical explorative techniques were used to statistically process the quantitative data, facilitating the examination of sample distribution according to the chrono- logical and typological constrains of structures and decorative elements. The results showed a high level of specialization in the “recipes” of mortar and concrete, tailored to their specific functions. Chronology also appeared to significantly influence the composition of cementitious compounds. Certain materials exhibited sophisticated pozzolanic properties, particularly in cases requir- ing waterproofing. Techniques for achieving hydraulicity included adding broken ceramics, in fragments or dust, or pyroclastic rocks (pozzolanas) to lime-based mixtures. The latter were primarily sourced from the Phlegraean Fields District (Pulvis Puteolanus), in the Gulf of Naples, and transported by ship to the Norther Adriatic town. Additionally, the calcination of cherty and impure limestones was documented to produce a peculiar kind of natural hydraulic lime. From a pure mineral-chemical perspective, in addition to traditional Ca-based pozzolanic products (such as C-S-H, C-A-H, and C-A-S-H phases), distinctive Mg-based para-pozzolanic gels (known in cement chemistry notation as M-S-H or M-A-S-H phases) were often observed. These gels develop as a result of the unusual reaction between silicates (chert) and dolostone aggregates in alkaline conditions. This extensive sampling effort provided valuable insights into the relationships among the crafts involved in the construction and decoration of ancient buildings in Aquileia. The conclusions drawn from this research represent a significant advancement in the understanding of ancient cementitious materials, offering new perspectives for discussing the sourcing dynamics of raw materials, the technical expertise, the constructive know-how and economic-productive processes of the ancient world.