Siegfried Siegesmund - Monument Future

In this study, it was used a combined methodology including historical archival study and laboratory analysis, in order to identify the decay patterns and evaluate their progress in the course of time, especially during the last 100 years. Moreover, the results of this study uncovered new features about the polychrome layers on the rock reliefs, which can be used in future conservation planning in order to save as much as possible of the historical materials. Analysis of these materials together with recording of their traces and relevant materials on the maps, were carried out for the first time on the tomb of Xerxes. The results showed interesting features about the origins of the phosphorus-containing layer which is in agreement with other evidence of polychromy during the second half of the Achaemenian period.

The authors want to thank Dr. H. Fadaei, the head of Persepolis-Pasargadae scientific foundation for supporting this study.

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Ridolfi, S., Laurenzi Tabasso, M., Askari Chaverdi, A., Callieri, P., 2018. The Finishing Technique of the Stone Monuments of Persepolis: Further Studies and New Findings Through the Use of Non’Destructive Analytical Techniques. Archeometry, 61(2): pp. 272–281.

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Sohrabi, M., Favero-Longo, S., Pérez-Ortega, S., Ascaso, C., Haghighat, Z., Talebian, M., Fadaei, H., De los Ríos, A., 2017. Lichen colonization and associated deterioration processes in Pasargadae, UNESCO world heritage site, Iran. International Biodeterioration & Biodegradation, 117: pp. 171–182.

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Emilia Vasanelli 1 , Angela Calia 1, Giovanni Quarta 1, Davide Melica 2, Maurizio Masieri 1, Antonio Monte 1, Francesco Micelli 3

IN: SIEGESMUND, S. & MIDDENDORF, B. (EDS.): MONUMENT FUTURE: DECAY AND CONSERVATION OF STONE.

– PROCEEDINGS OF THE 14TH INTERNATIONAL CONGRESS ON THE DETERIORATION AND CONSERVATION OF STONE –

VOLUME I AND VOLUME II. MITTELDEUTSCHER VERLAG 2020.

1CNR-ISPC National Research Council – Institute of Science for Cultural Heritage, University Campus, Prov.le Lecce Monteroni, 73100, Lecce, Italy

2Conservation Scientist via Carlo D’Angiò 31, 73043 Copertino (Lecce), Italy

3University of Salento Dept. Innovation Engineering University Campus, Prov.le Lecce Monteroni, 73100, Lecce, Italy

Thermal decay induced by fire produces chemical and mineralogical alterations, which are often accompanied by discoloration changing the aesthetic characteristics of the stone surfaces. It may compromise also the load-bearing capacity of the masonry elements and lead to stability problems.

Here we report on the investigation of the fire effects on a soft calcarenite used within a masonry building.

Mineralogical transformations of iron hydroxides were detected through XRD and accounted for red discolouring. They were confirmed by DSCTGA analyses and indicated a temperature around 300 °C affecting the stone. Microstructural modifications were investigated by means of optical microscopy and UPV propagation test. A quantitative determination of physical parameters such as color, bulk density, porosity and water uptake was also performed. Implications of thermal stress with the mechanical properties were assessed through uniaxial compressive tests. Thermal effects on the stone microstructure were not microscopically evident. On the contrary, UPV decreases indicated a microfissuring, but this slightly affected porosity, water uptake and compressive strenght.

Stone materials involved in fires may be affected by a variety of phenomena, which can change their original properties and related performance in buildings. Depending on the temperature, both chemical and mineralogical trasformations may occur and lead to stone colour changes (Kompaníková et al. 2014). In addition, volume variations due to phase transitions (Calia et al, 2015), different thermal expansion of adjacent minerals (Vázquez et al., 2015) or strongly anisotropic thermal properties of some minerals (e. g. calcite) (Siegesmund et al., 2000) may affect the stone microstruture and lead to microfissuring, which may increase the stone susceptivity to weathering and compromise its load-bearing performance (Sippel et al., 2007). Thermally induced effects on the microstructure strongly depend on the inherent stone characteristics and have a high incidence on low porosity materials, due to the dense packing of crystals and grains (Yavuz et al., 2010). Thermal behaviour has been studied for a variety of stones, which mainly include compact materials (Martinho et al., 2018), while poor literature deals with heating damage on porous stones (Gomez-Heras et al., 2006; Brotóns et al., 2013; 78Franzoni et al., 2013). In this paper we present the results of a case study where the effect of a fire on highly porous calcarenites were assessed by using integrated investigation techniques.

The study was carried out on the stone materials used within the masonry of the ACAIT (Azienda Cooperativa Agricola Industriale del Capo di Leuca) industrial building (Fig. 1). The building was a factory for the processing of the tobacco, in the province of Lecce (Southern Italy). It was built in the early 1900 and dismissed at the end of the 1980s. The factory is a remarkable example of the industrial archaeological heritage relating to the tobacco manufacturing, a flourishing activity in which Puglia region had a leading role on a national basis in the past century.

The original building developed on the ground floor only and it has undergone several enlargements over the years. Like all industrial buildings, it has a simple and modular layout, composed of large rooms with corner-vaulted (“volta a spigolo”) roof, typical of the local tradition, load-bearing pillars and masonry walls with regular local limestone ashlars.

Figure 1:The building of the tobacco factory ACAIT affected by a partial collapse.