Archaeometric study of mortars and plasters from the Roman City of Pollentia (Mallorca-Balearic Island)

Abstract

This paper focuses on the compositional characterization of 18 samples of mortars and plasters from the Roman city of Pollentia (Mallorca, Balearic Islands, Spain). In particular, they were taken from the residential area of the site named Sa Portella. The characterization of these samples was carried out through different analytical techniques: optical microscopy (OM), X-ray powder-diffractometry (XRPD), X-ray fluorescence (XRF) and Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS). A detailed image analysis was also carried out through the use of the software “JMicro Vision” to determine the percentage of aggregate and binder used in the samples and to study their macroporosity. The results of these analyses have allowed to determine the mineralogical, petrographical and chemical characteristics of the samples and have provided useful information about the building techniques, the raw materials used and the production technology of mortars and plasters during Roman times. Both the compositional comparison among the samples, and the statistic multivariate analysis, show relevant differences among groups of mortars and plasters from the same buildings and similarities among samples belonging to different buildings, suggesting the presence of several constructive phases or different manufacturing techniques in the residential area of Pollentia.