The Market Gate of Miletus: damages, material characteristics and the development of a compatible mortar for restoration
- 127 Downloads
The indoor exhibit of the Market Gate of Miletus is unique for an archaeological monument. The reconstruction of the gate was done in such a way that most marble fragments were removed leaving cored marble columns 3–4 cm in thickness. These cored columns were mounted on a steel construction and filled with different mortars or filled with specially shaped blocks of brick combined with mortar. All the missing marble elements were replaced by copies made of a Portland cement based concrete, which is compositionally similar to the original building materials. During the Second World War the monument was heavily damaged by aerial bombardment. For 2 years the Market Gate of Miletus was exposed to weathering, because a brick wall protecting the gate was also destroyed. The deterioration phenomena observed are microcracks, macroscopic fractures, flaking, sugaring, greying, salt efflorescence, calcitic-sinter layers and iron oxide formation etc. The rapid deterioration seems to be due to indoor atmospheric effects, and also by a combination of incompatible materials (e.g. marble, steel, mortar, concrete, bricks etc.). Compatible building materials like mortars or stone replacing materials have to be developed for the planned restoration. The requirements for restoration mortars are chemical-mineralogical and physical-mechanical compatibilities with the existing building materials. In detail this means that the mortar should ensure good bonding properties, adapted strength development and not stain the marble when in direct contact. The favoured mortar was developed with a hydraulic binder based on iron-free white cement and pozzolana based on activated clay. A special limestone and quartz sand mixture was used as an aggregate. The cement was adjusted using chemical additives. Specially designed tests were applied extensively to prove whether the developed mortar is suitable for the restoration of this precious monument.
KeywordsMarket Gate of Miletus Damage appraisal Marble deterioration Indoor environment Development of a restoration mortar
We are grateful to V. Kästner from the State Museum of Berlin—Prussian Cultural Heritage for his help in the investigations. Our work was supported by the Deutsche Bundesstiftung Umwelt. Furthermore, special thanks should also go to Prof. W.-D. Heilmeyer, V. Kästner, Prof. M. Schmidt, T. Weiss, M. Hoppert, E. Rothert, V. Maack, K. Müller, C. Gross, M. Pfanner and especially to J. Rüdrich for their excellent collaboration on this project.
- DIN EN 197-1: Cement—part 1: composition, specifications and conformity criteria for common cements. German version EN 197-1:2000 + A1:2004; 2004-08-00. Beuth Verlag GmbH, BerlinGoogle Scholar
- DIN 1053-3: Reinforced masonry; design and construction. 1990-02-00. Beuth Verlag GmbH, BerlinGoogle Scholar
- DIN 18555-3: Testing of mortars containing mineral binders; freshly mixed mortars containing aggregates of dense structure (heavy aggregates); determination of consistence, bulk density and air content. 1982-09-00. Beuth Verlag GmbH, BerlinGoogle Scholar
- DIN EN 1015-9: Methods of test for mortar for masonry—part 9: determination of workable life and correction time of fresh mortar. German version EN 1015-9:1999 + A1:2006; 2007-05-00. Beuth Verlag GmbH, BerlinGoogle Scholar
- DIN 1164-7: Portland-, iron Portland-, blast-furnace-, and trass cement; determination of strength. 1978-11-00. Beuth Verlag GmbH, BerlinGoogle Scholar
- Hoppert M (2004) Markttor von Milet: Schadwirkung durch Biofilme. In Das Marktor von Milet: Schadensanalyse und modellhafte Sanierungskonzepte. DBU-Abschlussbericht, GöttingenGoogle Scholar
- Rüdrich J (2003) Gefügekontrollierte Verwitterung natürlicher und konservierter Marmore. Dissertation, Universität Göttingen, 158 S. http://webdoc.sub.gwdg.de/diss/2003/ruedrich/ruedrich.pdf
- Schmidt M, Middendorf B (2004) Verformungsmessungen am Markttor von Milet. In Das Marktor von Milet: Schadensanalyse und modellhafte Sanierungskonzepte. DBU-Abschlussbericht, GöttingenGoogle Scholar
- Siegesmund S, Middendorf B, Maack V, Rüdrich J (2005) Das Markttor von Milet: Schadensbilder, Materialcharakteristika und Entwicklung von Restauriermörtel. In: Siegesmund S, Snethlage R, Auras M (Hrsg.) Stein-Zerfall und Konservierung. Edition Leipzig, Leipzig, pp 166–174Google Scholar
- Siegesmund S, Ruedrich J, Koch A (2008) Marble bowing: comparative studies of three different public building facades. Environ Geol. doi: 10.1007/s00254-008-1307-z
- Strocka VM (1981) “Das Markttor von Milet”, 128. Winkelmannsprogramm der Archäologischen Gesellschaft zu Berlin. Verlag Walter de Gruyter & Co., BerlinGoogle Scholar