Volcanic Pozzolan from the Phlegraean Fields in the Structural Mortars of the Roman Temple of Nora (Sardinia)

Abstract

In this paper, we discuss the presence of volcanic pozzolans in the structural mortars of the Roman Temple of Nora in Sardinia (3rd c. AD), represented by pyroclastic rocks (pumices and tuffs) employed as coarse and fine aggregates. The provenance of these materials from the Phlegraean Fields was highlighted through a multi-analytical approach, involving Polarized Light Microscopy on thin sections (PLM), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), Quantitative Phase Analysis by X-ray Powder Diffraction (QPA-XRPD), and X-ray Fluorescence (XRF) investigations. These volcanic pozzolans, outcropping in the Bay of Naples between Pozzuoli and the Vesuvius, are traditionally associated with the pulvis puteolana, the famous pozzolanic ash prescribed by Vitruvius and Pliny in order to confer strength and waterproofing capabilities to ancient concretes. This is the first evidence of the trade of this volcanic material from the Neapolitan area to Sardinia, starting at least by the Middle Imperial Age. The use of the pulvis puteolana in the Roman Temple of Nora seems primarily targeted to strengthen above-ground masonries, while waterproofing capabilities were not strictly pursued. This opens new questions about the construction reasons for which the demand and commercialization for this product was intended.

MgO‐based binders

“…Long-term and durability studies of M-S-H cements are not reported in literature. However, M-S-H cements show a high resistance against carbonation [12,13] as also underlined by the observation of M-S-H in some Roman cements [41].…”

“…Magnesium from the seawater or clay water reacts with the amorphous silica from the degradation of C-S-H in cement leading to the formation of M-S-H [40]. M-S-H has also been observed in Roman cements rich in chert and dolostone [41] indicating a long-term stability of M-S-H. Electron microprobe, SEM/EDS and TEM analyses indicate that M-S-H contains not only magnesium, silica, hydroxides and water but that aluminium, calcium and iron can be incorporated in its structure [42,43].…”

Aquileia and its urban development in the light of recent and ongoing research

“…Since 2015, the University of Padova has been researching in the area of the Roman theatre of Aquileia (Comelli-Moro estates: Fig. 2: 6) (Ghiotto et al 2018;Ghiotto et al 2020;Ghiotto et al 2021;Dilaria et al 2023). 15 It is the latest of the main public buildings of 1 2 the Northern Adriatic city to be reliably identified, after some important hypotheses regarding its location had previously been put forward by archaeologist Luisa Bertacchi (Bertacchi 1995;Ghiotto 2019).…”

Archaeometric investigations on ancient funerary stone elements from the National Archaeological Museum of Adria (Rovigo, Italy)

“…This rock type, also known as "Pietra Tenera" (Soft Stone), refers to soft and easily workable limestones quarried in the Berici Hills, south of Vicenza. All the samples refer to the Oligocene Castelgomberto Limestone Formation [18] and they can be defined as grainstones, having a sparitic cement and abundant encrusting coralline Red Algae, ialyne foraminifera (nummulites and asterigerinids), bryozoans, serpulids and echinoids. The presence of benthonic miliolids foraminifera is relevant in the Costozza Stone variety (samples AD_74, Fig.…”