Florence City Centre Historical Mortars: Digital Image Analysis of thin sections in view of conservation actions

Some samples of bedding mortar collected from historical buildings in the city centre of Florence, a UNESCO heritage site since 1982, were analysed through infrared diffractometry and petrographic analysis. A first level of understanding of the mineralogical composition of the mortars was obtained. Then, through digital processing of images from thin sections observed in transmitted light, quantitative data about the composition of the analysed historical mortars were determined, such as the dimension of pores and aggregates, binder/aggregate ratio, and porosity grade. According to these results, a mix of a new mortar with chemical, physical and mechanical characteristics similar to the historical ones was determined. Some samples of this new mortar were made and then mechanically tested in the laboratory to improve mechanical performance and create a new fibre reinforcement system, compatible with historic buildings and as a precaution to prevent seismic damage.