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

Abstract

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

Archaeometric study of mortars from the Pisa’s Cathedral Square (Italy)

“…The use of mortars in architecture was carried out since prehistoric time until the present days [20][21][22][23][24]. Lime mortars had a very important key function in Roman architecture; in fact, Romans used mortars to make the load-bearing walls and partition walls of rooms, to plaster them for protection purpose or to decorate their surface with paintings [25][26]. Usually, they used both quick lime and hydraulic binders, obtained by adding pozzolanic materials characterized by hydraulic properties, the latter to increase strength of mortars [27][28][29].…”

The San Giovanni Baptistery in Florence (Italy): Assessment of the State of Conservation of Surfaces and Characterization of Stone Materials

“…The TGA results confirm the hydraulic behavior, as suggested by the presence of lumps of unburnt Alberese limestone in petrographic observations. The firing of marly limestone provides natural hydraulic lime, typically produced in the Florentine area [19,[37][38][39]. Finally, the mortar samples show, mainly, the presence of lumps which are typical of Alberese limestone, suggesting the use of this stone to produce lime.…”

Le tenaci malte della torre del castello di Cerreto Ciampoli (Siena, Italia)

“…Com'è noto, l'analisi mineralogico-petrografica e chimica delle malte storiche è particolarmente utile nella identificazione della natura e della provenienza delle materie prime e nel riconoscimento delle relative tecnologie di produzione (e.g. Cantisani, et al, 2018;Chiarelli, et al, 2015;Franzini, et al, 2000;Giamello, et al, 2017;Guasparri, et al, 2006;Lezzerini, et al, 2017;Moropoulou, et al, 2000;Riccardi, et al, 2007). Attraverso tale approccio si intende raccogliere elementi utili per l'identificazione di materiali e procedimenti tecnologici che hanno contribuito alla fabbricazione delle malte di eccezionali qualità della torre in oggetto, tanto da garantire la durevolezza della muratura fino ai nostri giorni ed impedire, in occasione del crollo, la frantumazione della struttura in elementi minuti.…”