Monument Future - Siegfried Siegesmund

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microrganisms. They form a dark film, which is also accompanied by pitting effects (Sohrabi et al., 2017). Microscopic observations showed that this is originally the same encrustation layer which is then contaminated with biological growth. The presence of micro-organisms in the pores of the encrustation layer caused a greyish or darker color. In places near the cracks and fissures conducting the rainwater, it went deeper and caused the detachment of stone pieces from the rock. Therefore, cross sections showed the presence of biologic material not only on the surface layer but also on the opposite side of the sample (Figure 6).

      Finally, a very interesting feature was identified in a few samples under the encrustation. SEM/EDX analysis shows a considerable amount of phosphorous in this layer (Figure 7). It is found that this feature is linked to the technique, which was used for polychrome decoration. The first finding of such feature was given nearly two centuries ago by the French archaeologist who discovered traces of blue paint on Darius tomb, under a thick layer of what was described as a calcareous cover, but currently we may classify as a crust layer (Dieulafoy, 1885: 227). There was no report about the polychromy on other tombs of Naqshe-Rustam, especially the Xerxes’s. However, during the conservation activities in the site a few traces of red paint were identified on the rock reliefs, which was given to the authors for analytical studies. We found the same layer with a high amount of P, interpreted as a ground under the paint in those samples.

      Similar phosphorous containing material, probably as a product of burning bones, was found in Persepolis, as a ground layer for painting, in constructions attributed to Xerxes era (Ridolfi et al., 2018).

      We need to continue the mapping and also to 76compare analytically our findings on Xerxes tomb with the earlier polychromy on the tomb of Darius. Moreover, this discovery enabled us to distinguish the traces of P-rich ground layer of the original polychromy from other superficial depositions on the rock reliefs. This provides an important measure for future conservation works in order to avoid errors such as overcleaning.

      Figure 6: Black Biofilm on the reliefs, (a) sampling location, (b) the cross-section of the stone surface with biofilm, (c) and (d) SEM graphs of the surface of same sample showing the biological growth in the porous structure of the crusted surface.

      Figure 7: White layer with traces of polychromy on the surface of reliefs, (a) sampling location, (b) cross-section of sample showing traces of red color on the surface with a ground layer between paint and stone, (c) SEM elemental map for Phosphorous.

       Conclusions

      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.

       Acknowledgements

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

       References

      Dieulafoy, M. 1885. Mission de Susiane. Note relative à la découverte sur le tombeua de Darius de sept inscriptions nouvelles. Revue Archéologique ser.3.6 : pp. 224–227.

      Della Valle, P., 1843, Viaggi di Pietro Della Valle, V. II, Brighton, G. Gancia.

      Fitzner B., Heinrichs K. & Kownatzki R., 1995, Weathering formsclassification and mapping, Verwitterungsformen – Klassifizierung und Kartierung. Denkmalpflege und Naturwissenschaft, Natursteinkonservierung 1. Ernst & Sohn, Berlin, pp.41–88.

      Fronteau, G., Thomachot-Schneider, C., Chopin, E., Barbin, V., Mouze, D., Pascal, A., 2010. Blackcrust growth and interaction with underlying limestone microfacies. Geological Society, London, Special Publications, 333: 25–34. Kaempfer, E., 1712. Amonitatum exoticarum politico-physico-medicarum fasciculi V, quibus continentur variae relationes, observationes et descriptiones Rerum Persicarum et Ulterioris Asiae. Lemgo. Meyer.

      ICOMOS-ISCS, 2008. Illustrated glossary on stone deterioration patterns, English/French version. MONUMENTS AND SITES, XV. Paris: ICOMOS.

      Masetti, C., 2018. Città varie e costumi il fin prescrisse. La Persia di Pietro Della Valle (1617–1623). Franco Angeli.

      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.

      Schmidt, E., 1970. Persepolis. Vol. III: The Royal Tombs and Other Monuments. Chicago: Oriental institute.

      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.

      UNI., 2006. 11187:2006 – Beni culturali – Materiali lapidei naturali ed artificiali – Pulitura con tecnologia laser. Milan: UNI – Ente Nazionale Italiano di Unificazione.

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       EFFECT OF FIRE ON THE DURABILITY OF A POROUS CALCARENITE: THE CASE STUDY OF A TOBACCO FACTORY IN TRICASE (LECCE, SOUTHERN ITALY)

      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.

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

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

       Abstract

      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

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