Assessments on the material properties of the Pietraforte stone of Florence (Italy) in conservation, restoration and construction

“Pietraforte” is the historic name of a turbiditic sandstone extensively used in monumental buildings of Florence from the Roman period to the early XX century. Today all the historical quarries are disused, and they have been reclaimed as urban areas or parks (e.g., Boboli Garden). No technical data on Pietraforte are available, although they would be valuable to drive the conservation of these exceptional monumental buildings. In this work the results of an experimental research are shown; the experimental campaign was aimed at investigating the mechanical properties of Pietraforte through both destructive and non-destructive tests. The analysed samples were extracted from some of the ancient quarries used for the historical buildings in the Florentine area. All the samples were tested according to international standards, in order to collect statistically consistent results in terms of the ultrasonic velocity of the P-waves and uniaxial compressive strength. A predictive model to relate the ultrasonic velocity and the uniaxial compressive strength is proposed on the basis of the obtained results. The collected experimental data refer to “fresh” intact rock and provide useful knowledge that can be used to design and calibrate the interventions on monumental buildings made of Pietraforte.