Vol.:(0123456789) 1 3 Journal of Thermal Analysis and Calorimetry https://doi.org/10.1007/s10973-020-09937-9 A multidisciplinary approach to the mortars characterization from the Town Walls of Gubbio (Perugia, Italy) Antonella Curulli 1  · Giampiero Montesperelli 2  · Sara Ronca 3  · Nicola Cavalagli 4  · Filippo Ubertini 4  · Giuseppina Padeletti 1  · Stefano Vecchio Ciprioti 5 Received: 31 December 2019 / Accepted: 10 June 2020 © Akadémiai Kiadó, Budapest, Hungary 2020 Abstract In the frame of the HERACLES (HEritage Resilience Against CLimate Events on Site) project, a set of cultural heritage sites was studied to improve their resilience against climate events. The mediaeval Town Walls of Gubbio, in the centre of Italy, are among these. Over the centuries, several factors including environmental actions and structural and material repairs have produced diferent criticalities, involving both structure and materials. A severe problem consists in the progressive degradation of the mortars binding the masonry. Since the wall body structure behaves/reacts properly only if the cohesion between mortar and stones is sufciently large, it follows that mortars degradation represents a quite signifcant issue that deserves a special attention. The present work focuses on the characterization of the mortars sampled in various parts of the Walls, corresponding to diferent historical periods, restoration measures and interventions. They were characterized to determine the corresponding mineralogical and chemical compositions along with morphological features and to investigate their mechanical properties. For that purpose, penetrometric and sclerometric tests on site and ex situ laboratory techniques, such as X-ray difraction, polarized light microscopy, scanning electron microscopy, thermogravimetry and diferential ther- mal analysis, were used to examine the weathering efects on mortars and more generally their degradation state, in order to plan appropriate restoration and repair actions. Keywords TG–DTA · Mortars · Binder · Aggregate · Hydraulicity degree · Masonry structure · Non-destructive test · SEM · XRD Introduction Built heritage is threatened by the weather patterns shifting and extreme events. For instance, an increase in tempera- ture together with changes in precipitation, relative humid- ity and wind can negatively afect the materials constitut- ing cultural heritage (CH) assets. This is because a change in the average climatic conditions as well as changes in the frequency and intensity of severe weather events can afect the biological, chemical and physical mechanisms, leading to degradation of the assets [1–5]. This includes an increase in the freeze–thaw cycle in northern Europe, extreme heat and droughts in the Mediterranean region, the overall decrease in summer precipitation in Europe and an increase in winter storms and heavy precipitation events in the Atlantic region. In addition, cultural heritage sites in coastal regions are particularly at risk due to sea-level rising and storm, while natural hazards such as foods, landslides, * Stefano Vecchio Ciprioti stefano.vecchio@uniroma1.it 1 CNR Consiglio Nazionale delle Ricerche, ISMN-Istituto per lo Studio dei Materiali Nanostrutturati, UOS Sapienza Via del Castro Laurenziano 7, 00161 Rome, Italy 2 Dipartimento di Ingegneria dell’Impresa, Università di Roma Tor Vergata, INSTM – Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via della Ricerca Scientifca, 00133 Rome, Italy 3 Dipartimento di Scienze della Terra, Sapienza Università di Roma, P.le Aldo Moro 5, 00185 Rome, Italy 4 Dipartimento di Ingegneria Civile ed Ambientale, Università di Perugia, Via G. Duranti 93, 06125 Perugia, Italy 5 Dipartimento di Scienze di Base ed Applicate per l’Ingegneria, Sapienza Università di Roma, Via del Castro Laurenziano 7, 00161 Rome, Italy