Study of ancient mortars from the Roman Villa of Pollio Felice in Sorrento (Naples)

The study of ancient mortars is an important aspect of building conservation: the choice of the materials has varied according to historical period, regional habits, and their specific function in the structure. Ancient mortars are composites, comprising hydraulic or aerial binding materials, and aggregates, passive or active, which may react with binding material. Moreover, they were modified during setting, hardening, and aging, according to processes not yet well known. In this paper, we present a study of ancient mortars from the Villa of Pollio Felice of Sorrento (Naples). The analysis has been performed by conventional techniques (grain-size distribution, lime-percentage analysis, optical and electron microscopy, and X-ray diffraction) and by means of a laboratory X-ray microdiffractometer equipped with an image plate detector. This system, applied for the first time to archaeological studies, can reach a spatial resolution of a few tenths of microns and it allows us to obtain separate phase identification of binder and filler particles.