Monument Future. Siegfried Siegesmund

by SIKA Company showed that the addition of a plasticizer to the suspension was not necessary to guarantee sufficient flowability. The gypsum suspension could easily be mixed and processed on-site. Observation of the injection process confirmed the very good flow behaviour of the suspension which ensured the closing of the cracks and cavities in the masonry. The grout remained flowable long enough and the quantity of the water taken from the surroundings were within limits. The masonry showed heavy vertical cracks and numerous holes and cavities in the interior, which had to be grouted from the bottom to the top of the wall with the developed gypsum suspension. First holes were drilled at a spacing of 30 to 50 cm along the course of the crack to grout the masonry. The holes had a diameter of 24 mm and depths of 30 to 80 cm. After completion of drilling, the entire masonry including the cracks was prepared for the subsequent rising grouting. For this purpose the cracks were cleaned of dust and loose objects and the parts of the masonry facade near the masonry facade were secured with loam mortar. This prevented contamination of the masonry during the grouting work and the preceding filling of the cracks. Then grouting was started from bottom to top (Figure 7).

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      Figure 7: Gypsum mortar injection into the cracked north wall of the west iwan. Right side: Bottom to top injection in sealed crack.

      It was frequently the case that the masonry could be grouted up to 1 m of height from one hole. This demonstrated an effective internal transport of material, with continuous grouting of the entire masonry being guaranteed. At each level, grout escaped at the various holes drilled round the buttress. In total, 7 tons of gypsum suspension were grouted to the east part of the north wall of the west iwan.

       References

      Bräunel, M. (2016). Takht-e Soleyman – vertiefende Bestandsaufnahme der Ruinenteile des westlichen Iwans in Vorbereitung der notwendigen statisch-konstruktiven Sicherung. Diplomarbeit an der Technischen Universität Dresden, Lehrstuhl für Tragwerksplanung, Fakultät Architektur, 2016, unpublished.

      Burkert, T., Fuchs, C., Sobott, R. (2019). Statisch-konstruktive Sicherungsarbeiten am westlichen Iwan der UNESCO-Welterbestätte Takht-e Soleyman, Iran. in Mauerwerk Kalender 2019, Ernst und Sohn, Berlin, 295–331.

      Glasenapp, M. (1910). Plaster, Overburnt Gypsum and Hydraulic Gypsum. – Cement & Engineering News, Chicago, Illinois, 47 pp.

      Fucke, D., Hansen, M. (2012). Takht-e Soleyman – vorbereitende Untersuchungen und Varianten zur Sicherung der Ruinenteile des westlichen Iwans. Diplomarbeit an der Technischen Universität Dresden, Lehrstuhl für Tragwerksplanung, Fakultät Architektur, 2012, unpublished.

      Huff, D. (2006). The Ilkhanid Palace at Takht-i Sulayman. Excavation Results, in: Komaroff, Linda (Ed.): Beyond the Legacy of Genghis Khan. Brill, Leiden 2006, 94–110.

      Jäger, W. (2017). Burning process of gypsum in the kiln in Tahkt-e Soleyman 20.05.2016. – Technische Universität Dresden, Faculty of Architecture, Chair of Structural Design, 12 pp.

      Jafarpanah, M. (2017). Burning process of gypsum in the kiln in Tahkt-e Soleyman 13.08.2017. – Takht-e Soleyman – UNESCO World Heritage Site, 13 pp.

      Lenz, R., Sobott, R. (2008). Beobachtungen zu Gefügen historischer Gipsmörtel. In: Gipsmörtel im historischen Mauerwerk und an den Fassaden. – Hrsg. von M. Auras und H.-W. Zier, WTA Schriftenreihe, Heft 30, 23–34.

      Lucas, H. G. (1992). Gips als historischer Außenbaustoff in der Windsheimer Bucht. Dissertation, Fakultät für Bergbau, Hüttenwesen und Geowissenschaften der RWTH Aachen.

      Müller, T., Baumgartner, L. P., Foster, C. T. Bowman, J. R. (2009). Crystal Size Distribution of Periclase in Contact Metamorphic Dolomite Marbles from Southern Adamello Massif, Italy. – Journal of Petrology, Vol. 50/3, 451–465.

      Naumann, R. (1977). Die Ruinen von Tacht-e-Suleiman und Zendan-e-Suleiman und Umgebung.

      Dietrich Reimer Verlag, Berlin, 126 pp.

      Sobott, R. (2018). Historic and modern gypsum mortar application at the Takht-e Soleyman, Iran. Report about on-site studies and results of sample analyses. unpublished, 25 pp.

      Soleymani, A., Pirak, M. (2012). Nachstellung von halbgebranntem und halbzerstoßenem Gips. (Transkribiert aus dem Iranischen) Quarterly Research Review of Razavi Architecture, Vol. 1, No. 1, 61–71.

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       EFFECTS OF ZEOLITES AND SWELLABLE CLAY MINERALS ON WATER-RELATED PROPERTIES AND THERMAL DILATATION IN VOLCANIC TUFF ROCKS

Alexandra Kück¹, Christopher Pötzl¹, Rubén López-Doncel², Reiner Dohrmann³, Siegfried Siegesmund¹

      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.

1 Geoscience Centre of the Georg August University Göttingen, Germany

2 Geological Institute of the Autonomous University of San Luis Potosí, Mexico

      3 Federal Institute for Geosciences and Natural Resources (BGR), Hanover, Germany

       Abstract

      The weathering of natural building stones in the South of Mexico is mostly controlled by the influence of atmospheric and meteoric water, thermal stress and the input of salts from the environment. Twelve varieties of volcanic tuff rocks from South and Central Mexico were analyzed regarding their petrographical and petrophysical properties, as well as their weathering behavior. The tuffs show a broad range of properties and differential weathering behavior. Moisture properties like water uptake, water vapor diffusion and hygroscopic water sorption as well as hydric expansion and salt crystallization show great dependence on the pore space properties and the content of swellable clay minerals or zeolites. The deterioration during salt bursting tests is controlled by both salt crystallization pressure and hydric expansion. Especially zeolite-rich samples show intense water-related weathering. Their sorption values and hydric expansion are high, while capillary water uptake is comparably low. The clay and zeolite-rich tuffs furthermore suffer from intense shrinking and fracturing during drying. The very high hydric expansion superimposes the salt crystallization pressure and the effect of thermal dilatation.

       Introduction

      Zeolites have an important influence on the weathering behaviour of natural building stones. Korkuna et al. (2006) found very small pore sizes for zeolite-rich samples (< 2 nm) resulting in a high specific surface area. The specific surface area, along with the pore size and connectivity of the pores is a controlling factor for water transport and retention in porous rocks and has a great influence on values like capillary water uptake, water vapor diffusion and hygroscopic water sorption (Siegesmund and Dürrast 2011).

      Hydric dilatation can cause a significant volume change in tuff rocks and is therefore an important weathering factor. Reasons for hydric expansion may be the presence of swellable clay minerals or a large percentage of micropores (e. g. Gonzales and Scherer 2004). The swelling of natural building stones with a high percentage of micropores may be explained by the process of disjoining pressure, but the process is still under discussion (e.g. Ruedrich