Siegfried Siegesmund - Monument Future

Figure 5:Correlation between a: hydric expansion [mm/m] and CEC [meq/100 g], b: hydric expansion [mm/m] and BET [m 2/g].

Figure 6:Correlation between a) hygroscopic water sorption at 95 % rh [wt.-%] and CEC [meq/100 g], b) hygroscopic water sorption at 95 % rh [wt.-%] and BET [m 2/g].

This work was supported by the German Research Foundation (Si-438/52-1) and the German Federal Environmental Foundation (AZ20017/481). We would like to thank J. L. Noria Sánchez, A. E. Andrade Cuautle and M. Á. González for their support of the onsite work. For the laboratory support and helpful comments we thank K. Wemmer, J. Menningen, W. Wedekind and C. Gross.

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Manuel Saba 1 , Juan Lizarazo-Marriaga 2 , Nicole Hernández-Romero 2, Cristina Tedeschi 3 , Edgar Quiñones-Bolaños 1

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.

1University of Cartagena, Research Group Esconpat, Faculty of Engineering, Cartagena, Colombia

2Universidad Nacional de Colombia, Department of Civil and Agricultural Engineering, Bogotá, Colombia

3Department of Civil and Environmental Engineering, Politecnico di Milano, Italy

4University of Cartagena, Research Group Environmental Modelling, Faculty of Engineering, Cartagena, Colombia

The deterioration of historical structures is a topic of primary importance due to their historical, cultural and economic importance. Aggressive environments around structures can depend on anthropogenic factors such as NO 2, SO 2gases among others, and environmental factors such as differential dilation, differential hydric dilation and crystallization. In the present study is proposed a physical-chemical characterization of the structure and quarry stone used for the replacement of deteriorated blocks of the defensive Wall of Cartagena, Colombia, UNESCO Cultural Heritage since 1984. X-ray and ionic chromatography identification were done in the structure stone. Furthermore, is proposed a Petrographical comparison between structure and quarry material as well as mechanical characterization of the quarry material.

The structure is composed mainly by soft limestone. Similar physico-chemical characteristics were found through X-Ray and Petrographical comparison, while salt crystallization is found playing a secondary role in the structure deterioration.

According to the United Nations’ Educational, Scientific and Cultural Organization (UNESCO), there are around 869 sites of cultural interest around the world (UNESCO 2019). They were selected for their historical relevance and uniqueness. All of them struggle with surrounding aggressive climate conditions that accelerate their deterioration. Currently, 53 of those sites are rated as being in imminent danger due to anthropogenic and natural factors (UNESCO 2019).

For example, the Fortifications on the Caribbean Side of Panama (Portobelo-San Lorenzo), part of the defensive colonial system built by the Spanish Crown to protect transatlantic trade, constitute a valuable example of 17th and 18th-century military architecture, whose integrity has been compromised by environmental factors, uncontrolled urban extension, development and the lack of maintenance and management. Dozens of structures have been destroyed in the past in the name of Civilization, or because of high deterioration and/or earthquakes. An example of this is the Noto Cathedral, Italy, a historic masonry building that suddenly collapsed in 1996 (Binda et al. 1999) 126producing during centuries a redistribution of stresses from the core of lime mortar concrete to the external cladding of stiff masonry. This is likely one of the causes of long-time damage of some ancient masonry towers. With these motivations, coupled processes of moisture diffusion, carbon dioxide diffusion and carbonation reaction are analyzed numerically. Due to the absence of models and data for lime mortar, one of the simplest models proposed for Portland cement concrete is adapted for this purpose. The results reveal the time scales of the processes involved and their dependence on wall thickness (size. Factors responsible for over-stressing and damaging the monuments and thus inhibiting their conservation are high levels of air pollution in the atmosphere, daily and seasonal cycles of temperature and humidity, sea spray (or salt spray), rising damp, atmospheric conditions (rainwater, wind and sunlight exposure (Kameni & Orosa 2016)).