Archaeometric study of natural hydraulic mortars: the case of the Late Roman Villa dell’Oratorio (Florence,Italy)

This paper shows the results of a multidisciplinary study carried out on the mortars from the Late Roman Villa dell’Oratorio (fourth-sixth ad), an aristocratic mansion built in the lower Valdarno (Florence, Italy). Thirty-one bedding mortar and plaster samples were analysed through optical microscopy, thermogravimetric analysis, X-ray powder diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy for determining the chemical, mineralogical and petrographic characteristics, while their main physical properties were measured by geotechnical procedures. The collected data indicates that the analysed mortars are made up of very fine to coarse river sand aggregate mixed with white to yellowish-white natural hydraulic lime binder mainly consisting of mixtures of prevailing calcite and hydraulic compounds. With regard to the origin of the raw materials, the aggregates were recognized to be selected Arno river sands, and the binders are the burning product of a local marly limestone (ex Alberese). Therefore, the mortars of the Late Roman Villa dell’Oratorio are one of the first uses of natural hydraulic lime in the lower Valdarno.     

A short note on the archaeometric study of two sculptures in the <Emphasis Type="Italic">Gabinetto Segreto</Emphasis> of Naples National Archeological Museum: the ‘Pan and the She-Goat’ group and the ‘Bikini Venus’

Presented here are the results of an archeological and archaeometric study of two famous marble sculptures displayed in the Gabinetto Segreto of the National Archeological Museum of Naples: the “Pan and She-Goat” group from the Villa of the Papyri at Herculaneum and the statue of the “Bikini Venus” leaning on a statuette of Priapus from the House of Julia Felix in Pompeii. This study offers some art historical observations about the sculptures and the first minero-petrographic (polarizing microscopy on thin section and x-ray diffraction on powders) and isotopic (C and O stable isotope ratio) investigation of their marble types. The results indicate that the “Pan and She-Goat” group employed the statuary white Carrara variety, while the Parian lychnites was used for the “Bikini Venus”. Analyses proved also that the red finishing layer present on the latter statue is composed by sandyx.     

White and Coloured Marbles of the Roman Town of Urbs Salvia (Urbisaglia,Macerata, Marche,Italy)

The results of an archaeometric study concerning the coloured stones and 14 white marble sculptures found in the ancient city of Urbs Salvia (Urbisaglia, Macerata) – one of the main Roman archaeological sites of the Marche region (east central Italy) – are presented here. Data show the presence of the most important decorative stones used by the Romans, originating in all of the Mediterranean provinces, from Egypt and North Africa to Asia Minor, Greece, Gallia, Iberia and Italy. Thirty‐one different coloured lithotypes have been identified, including red and green porphyries as well as marmor phrygium and numidicum, namely the four most expensive stones cited in Diocletian's edict. Crustae of marmor chium, taenarium, chalcidicum, scyreticum, lucullaeum and sagarium also feature. Another significant presence is that of coloured stones that are generally rare, even in Rome and Ostia, such as cipollino mandolato (which is very abundant at Urbs Salvia, more than anywhere outside Gallia), broccatello di Spagna, alabastro a pecorella, lapis ophytes, brecciated facies of marmor iassene and cottanello antico. Worthy of mention, too, is the abundant presence of so‐called Roman breccia from Lez (Upper Garonne valley, French Pyrenees), a stone never reported outside Gallia. The 14 marble sculptures analysed come from public and private buildings of the Roman city and are now exhibited at the Archaeological Museum of Urbisaglia. Our petrographic and isotopic analyses show that they are made of Lunense (five), Pentelic (three), Parian lychnites (three), Thasian (three) and Proconnesian (one Corinthian capital) marbles. The quality of the coloured stones identified, together with the presence of sculptures made of precious imported white marble varieties, reveals an opulent town and a local patronage wishing to decorate public buildings and rich houses with the most sought‐after marbles of Rome.     

Assessment of material characteristics of ancient concretes,Grande Aula,Markets of Trajan,Rome

The Grande Aula, or Great Hall, of the Markets of Trajan (AD 96 to 115) is an intact example of the domed, concrete architecture of imperial Rome. Petrographic, x-ray diffraction, chemical, and SEM analyses demonstrate that wall mortars contain Pozzolane Rosse volcanic ash aggregate (harenae fossiciae) and strätlingite, a complex calcium aluminate cement hydrate (C₂ ASH₈) that gives modern cements good durability and compressive strength. Specific gravity tests and a new petrographic method for assessing bulk densities indicate unit weights of about 1750 kg/m³ for the wall mortars and 1430–1640 kg/m³ for the pumice bearing, vaulted ceiling mortars. Innovative point load source tests record the tensile strengths (f_t) of the aggregate and interfacial elements of the conglomeratic concrete fabric. These suggest f_t of about 2.7 MPa for brick, 1.2 MPa for Tufo Lionato tuff, and 0.9 MPa for Tufo Giallo della Via Tiberina tuff coarse aggregate (caementa), based on a tentative, approximate correlation with splitting (Brazilian) tests. The pozzolanic mortar and interfacial zones have lower f_t in the range of 0.8 MPa to 0.5 MPa. The relatively low mortar strength and its somewhat tenuous adhesion to the coarse aggregate suggests that the caementa may have arrested the propagation of tensile microcracks that formed in the mortar, thereby increasing the composite tensile strength of the concrete. Roman builders selected the complex aggregate mixes to optimize the performance of the wall and vault concretes.