The Case Study of the Medieval Town Walls of Gubbio in Italy: First Results on the Characterization of Mortars and Binders

Abstract

Good conservation and restoration practices of cultural heritage assets rely on the knowledge of original materials. In the framework of the HERACLES Project (HERACLES-HEritage Resilience Against CLimate Events on Site, H2020 Grant Agreement 700395), dealing with the effects of climatic actions and natural hazards on built heritage, a set of important heritage sites are currently under study to improve their resilience against climate events. Among these are the medieval Gubbio Town Walls in Italy. The present work focuses on the mortars and binders of this monument and collected samples related to different parts of the Walls, corresponding to various historical periods of construction and interventions. They were characterized to determine their minerochemical composition, thermal behavior, and morphology. For that purpose, ex-situ laboratory techniques, such as X-ray diffraction (XRD), wavelength dispersive X-ray fluorescence (WDXRF), optical microscopy (OM), polarized light microscopy (PLM), scanning electron microscopy (SEM), and simultaneous differential thermal analysis and thermogravimetry (TG-DTA) were used to discern trends in different sampling areas due to construction/reconstruction periods and building techniques.

Economic and Societal Impacts on Cultural Heritage Sites, Resulting from Natural Effects and Climate Change

“…Since 1901, it has hosted the town museum, presenting an art gallery, ceramics section, archaeological and oriental collections, and a section on the period leading to the unification of Italy (Risorgimento). Since the nineteenth century, many restorations were made, as follows: the re-building of the main stairs; reinforcement interventions with anti-seismic techniques after the earthquakes of the early 1980s, particularly the one of 1984; the cleaning of the façade and interior walls; optimization of the museum lighting and plumbing and the restoration of the wooden external portals and doors [39][40][41][42][43].…”

Mortars from the Palace of Knossos in Crete, Greece: A Multi-Analytical Approach

“…However, the degree of hydraulicity calculated by TG-DTA shows some differences, indicating values corresponding to, or closer to, air lime mortar When considering the CO 2 /H 2 O loss ratio in Table 5, calculated from TG values, the degree of hydraulicity of the mortar can be inferred, because the lower the value of this ratio, the greater the degree of hydraulicity of the mortar. The literature considers that ratios above 10 correspond to aerial lime mortars, while the values between 3.5 and 10 are considered hydraulic mortars, and below 3.5 are considered pozzolans [10,[46][47][48]. Based on the values obtained, it is possible to observe that KN-BM1A presents a value compatible with that of an aerial mortar, and the other mortars present values corresponding to hydraulic mortars.…”

Evaluation of Material Characteristics and Structural Dynamic Properties of a Historical Church: The Case of 19th Century Bursa Derekoy Church (Ayia Paraskevi)

“…In studies on aggregate granulometry, the regular size of the grains is associated with the quality of the mortar. Moreover, a good mixing process is recommended during mortar preparation in order to ensure homogeneous distribution of aggregates [38].…”