Aqua Virgo: first characterization of mortars and plasters from the inner duct

Aqua Virgo is the ancient Roman aqueduct, inaugurated in 19 BC, that today still carries water to Fontana di Trevi. It is the only aqueduct built by ancient Romans for their capital that never stopped working, even when all the other aqueducts have been damaged during barbarian invasions (Pace, 2010). Two sectors of the inner underground duct of the aqueduct have been explored in this research: one still functioning area located under Pincian Hill, from San Sebastianello reservoir to the spiral staircase of Villa Medici, and one segment (now in disuse) between Via del Nazareno, Via dei Due Macelli and Via del Tritone. A total of 17 mortars and plasters samples have been collected from different parts of the inner duct (vault, lateral walls, inner part of walls, covering plasters) and 3 samples also from the cocciopesto of a duct that intersect Aqua Virgo just before Via del Nazareno, named “Y” (Baumgartner, 2017). A multi-analytical approach has been applied for the archaeometric characterization of the materials constituting the binder and the aggregate, and the reactions occurred between them: optical microscopy in thin section (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM-EDS), and thermogravimetric analysis on the binder fraction (TGA). As Aqua Virgo has a millenary working history, the aim of this work is to characterize what are supposed to be original materials from the Roman period and compare them with subsequent restorations; also, to compare the samples from aqueduct “Y”, whom attribution is still unknown (but it is supposed to be antecedent), with the ones of Aqua Virgo. REFERENCES Baumgartner M. (2017) - Roma rinascente: la città antica tra Quirinale e Pincio. De Luca editori d'arte, 295 pp. Pace P. (2010) - Acquedotti di Roma e il De aquaeductu di Frontino. Consiglio Nazionale delle Ricerche (CNR), 326 pp.