Multi-analytical approach to the characterization of mortars from Roman mosaics: a case-study from Conimbriga, Portugal

A.P. Rodrigues*a,b, F. Carvalhoc, R.J.C. Silvac, L.C. Alvesa, V.H. Correiad, J. Coroadoe, L.M. Ferreiraa, J.P. Veigac

a1C2TN, IST-UL,Campus Tecnológico e Nuclear, 2695-066 Bobadela, Portugal

*bDep. Conservação e Restauro, FCT-UNL, 2829-516 Caparica, Portugal

cCENIMAT/I3N, UNINOVA, Dep. Ciências dos Materiais, FCT-UNL, Campus de Caparica, 2829-516 Caparica, Portugal

dMuseu Monográfico de Conímbriga — Museu Nacional, 3150-220 Condeixa-a-Nova, Portugal

eTECHN&ART, Inst. Politécnico de Tomar, 2300-313 Tomar, Portugal

The cubiculum’s mosaic in the House of Trident and Sword, excavated between 2008 and 2010, is a black and white mosaic, set on four strata of lime-based mortars with different features.

The main panel underwent no intervention since that date, except mechanical cleaning of tesselatum and reburial with geotextile and excavated soil for protection. This enabled a multi-analytical study, resulting in the extensive characterisation of original, naturally aged, Roman mosaic components – mortars and tesserae. This work focuses on mosaic’s mortars, analysed by X-ray diffraction (XRD), optical microscopy (OM), Ion Beam Analysis (IBA) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS).

These mortars were typically produced by mixing lime, sand and crushed ceramics XRD results indicate calcite and quartz as the main crystalline phases present in the samples, corroborated by OM results. Further results using IBA and SEM-EDS for chemical and morphological analysis of the different mortar components will be shown to ascertain the conditions of these materials in an attempt to better understand this historical legacy and to promote good practices in future conservation approaches of this historical site.

Abstract Presented to the Scientific Symposium Frontiers in Heritage Science, World Meeting, Paris 2019, 14th–15th February