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,