On-Tech: characterization of ancient mortars for the development of new sustainable materials

One of the main challenges in the field of conservation is the development of innovative restoration products respecting the environment and the operator who works on cultural heritage. In this scenario, mortars and building materials require special attention especially because of the CO2 production linked to the cement industry, which is the third anthropogenic source of this type of emissions. This project, therefore, aims to provide innovative mortars resistant and compatible with ancient materials, which minimize CO2 emissions and are environmentally friendly. The mortars were produced starting from the ancient Roman recipe used for the Traiano-Paolo Aqueduct (Rome, I-II century A.D.) which proved highly resistant and durable thanks to a perfect mix of raw materials, grain size and production technology. The first phase of the study concerns the characterization of the starting raw materials considered perfect in terms of compatibility with ancient materials. In detail, pozzolans from different quarries around Bracciano Lake (Rome) were sampled to assess their characteristics. The mineralogical-petrographic and chemical composition have been studied through a multi-analytical approach. The results showed several differences in matrix, leucite crystals (presence, size, type), amount of phenocrystals (clinopyroxenes and feldspar) and porosity. For the experimental step the vesicular pyroclastic materials, with abundant crystals of leucite, clinopyroxenes and high porosity were chosen as starting material for the new formulations which were then characterized through the use of optical microscopy (OM), X-ray diffraction (XRPD), Fourier infrared spectroscopy (FTIR) and scanning electron microscopy (SEM-EDS).