ERE1.4

The analysis and interpretation of past climate data and simulations of climate models for future periods will allow us to know future climate conditions and their differences with past ones. One of the many applications of these analyzes is the study of the impacts of climate change on two types of cultural heritage that differ due to their geographical location and therefore their climatic conditions, as are vernacular cultural heritage in Europe and archaeological sites in Latin America, but they share a fundamental similarity in terms of the use of materials and construction techniques.

The first objective of our study is to review and quantify the impacts of combined climate (mean and extreme) and pollution on building materials of cultural heritage under future IPCC socioeconomic scenarios with high and low mitigation measures at years 2030, 2050 and 2070, using peer-reviewed dose-response equations.

We also focus on the degradation effects due to compound extreme events (heatwave, dry spells and extreme rainfall/flood) of each of the selected regions of our case study (European project SCORE: Sustainable COnservation and REstoration of built cultural heritage 2021-2024), in order to determine how future climatic conditions may affect the cultural heritage of some sites in Europe and Latin America. The foregoing by applying these climatic conditions in different models, based on scientific literature, that allow determining the consequences of these conditions on the materials in which these structures were built.

Finally, based on the literature review, we deliver preliminary results on a “cocktail of extreme events” experiment in laboratory specifically designed to quantify the damages and degradation of building materials due to a realistic series of adverse climate and pollution events.

How to cite: Esteban Cantillo, O. J., Menendez, B., and Quesada, B.: Climate change impact on vernacular and archaeological cultural heritage building materials in Europe and Latin America, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1776, https://doi.org/10.5194/egusphere-egu22-1776, 2022.

Norway, nowadays, still preserves outstanding examples of traditional Scandinavian wooden architecture called stavkirker (i.e., stave churches), these are typical Norwegian medieval churches built since 11^th-12^th Centuries with posts and staves as load bearing elements. This homogeneous group of immovable cultural heritage share similar architectural features, construction materials, as well as tangible and intangible values. They represent the highly developed tradition of wooden buildings that extended at these latitudes during Middle Ages and incorporate a large reuse of decorative and construction elements originating from other stave churches built in earlier centuries. Besides having similar use and maintenance requirements still today, the stave churches have similar vulnerability, as well as risk assessment and preservation needs.

For their protection it becomes fundamental to analyse and predict the impact of climate change in term of expected extreme temperature and rainfall events. In fact, modification of temperature (and consequently relative humidity) and/or of precipitation amount may cause rot to the Pine wood material constituting the churches or may enhance the mechanisms of biological and mechanical decay with an ultimate loss of valuable building assets.

This contribution focuses on the whole group of the still existing 28 stave churches spread over 6 regions in centre-south Norway with different climate, from temperate continental climate/humid continental climate (Dfb in the Köppen classification) to cool continental subarctic climate (Dfc) passing through the Tundra climate (ET). The work introduces an overview of the churches` architectural categorization, location, and flood vulnerability; then it focuses on climate change impacts. For the analysis of temperature and precipitation extreme events the modelled grid data from the Norwegian Climate Service Center (https://nedlasting.nve.no/klimadata/kss)  over 1x1 km spatial resolution have been used. These forecasts have been produced using the regional climate model simulation COSMO-CLM¹ (Consortium for small scale modelling in Climate Mode) considering the Representative Concentration Pathways RCP4.5 (i.e., slow increase of concentrations of greenhouse gases in the atmosphere until 2050 followed by emission reduction over time with, in addition, a human-induced radiative forcing at 4.5 W/m2). More than 100 Gb of data were elaborated to create a novel database with daily temporal resolution over two reference time periods i.e., the recent past (RP, 1991-2020) and the far future (FF, 2071-2100) for the location closest to each stave church. Further the analysis concentrates on extreme precipitation and temperature occurrences (e.g., > 99.99 percentile) investigated as cumulative distribution function (CDF) and complementary cumulative distribution function (CCDF). Results highlight expected anomalies in extreme events for all the 28 locations and report the total extreme precipitation and temperature related hazards as indexes which easily allow to categorize the change in risk for each stave church.

References:¹Rockel, B., Will, A., & Hense, A. (2008). The regional climate model CLM. Meteorologische Zeitschrift, 17, 347–348

How to cite: Bertolin, C. and Sesana, E.: Analysis of Climate Change Impacts on the still existing 28 Norwegian Stave Churches, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7880, https://doi.org/10.5194/egusphere-egu22-7880, 2022.

The intensity and frequency of extreme weather events in Europe are one of the most dangerous consequences of a warming climate. Some regions suffer more under heat waves and droughts, while others are experiencing extreme rainfalls. Thus, for example, a severe flood in July 2021 in several European countries caused widespread damages particularly in Belgium and Germany.

Which extreme weather events are to be expected in the future? How can the damage of irretrievable historical sites be avoided or, at least, limited or dealt with? All these questions are addressed in the three-year research project KERES, which is funded by the German Federal Ministry of Education and Research (BMBF) and is coordinated by the Fraunhofer ISC together with the Fraunhofer EU Office in Brussels.

As first step the regional relevance of future extreme weather events in Germany will be investigated.  This information will be further used to estimate the potential damages to buildings and outdoor facilities. The precautionary and responsive measures to manage potential or acute damage situations will be investigated as well. The designed methodologies will be tested for five case studies including World Heritage Sites (historical buildings and historical gardens)  in Germany.

The major tools of KERES include building component and indoor climate simulations and high-resolution urban climate models. The necessary input will be taken from the most recent ensemble of regional climate change projections of the EURO-CORDEX Initiative (www.euro-cordex.net).  As a result, an ontology-based information system will be designed for managing the expected damage situations.

We will present first results from the KERES project. The discussion will be focused on how to access and visualize the robustness of projected changes of extreme weather events in a way oriented to individual cultural heritage sites.

How to cite: Kotova, L., Leissner, J., Winkler, M., Antretter, F., Kilian, R., Mossgraber, J., Reuter, J., Hellmund, T., Dolgov, A., Matheja, K. M., Rhode, M. R., Pollmer, U., and Mikolajewicz, U.: Making use of climate information for protecting cultural heritage from extreme weather events in a warming world, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2850, https://doi.org/10.5194/egusphere-egu22-2850, 2022.

The climate of the city of Tønsberg in Norway is cold and humid. As a result, the brick-made historic buildings in this city are threatened by frost damage. Climate change is expected to affect the action of this degradation mechanism. In the current research, climate data resulting from the REMO2015 driven by the global model MPI-ESM-LR were used for periods 1960-69, 2010-2019, and 2060-69 representing the past, present, and future climate conditions. In addition, data from the ERA5 reanalysis for the present conditions, 2010-19, were used to assess the accuracy of the climate model data. Given the climate excitations, the freeze-thaw events were calculated according to two climate indices, i) the events of temperature decrease below 0^oC and ii) by considering that freezing occurs below -3^oC and thawing occurs above 1^oC. Moreover, a material response-based index that takes into account the temperature and the moisture content of a 5mm layer in the exterior side of the wall assembly was calculated. Prior to its calculation proper hygrothermal simulations were performed. According to this index, the critical temperature and degree of saturation that characterize a freeze-thaw event are 0^oC and 25%, respectively. From the climate model data and the first climate index, the 0^oC crossings that were calculated are 400, 340, and 223 under the past, present, and future conditions, respectively. The respective number of the freeze-thaw events that were calculated by using the second climate index are 49, 31, and 27 which are significantly lower. From the data obtained from the ERA5 reanalysis, the number of freeze-thaw events that were calculated is 425 and 123 for the first and the second climate index, respectively. This difference is attributed to the underestimation of the air temperature in the climate model data, which results in a lower number of temperatures hovering around the examined thresholds during winter. The results of the material response-based index show a minor frost risk for the brick-made wall assemblies which is reduced through the years. The southeast-oriented walls were the ones with the highest exposure to driving rain and the greatest frost damage risk. For this orientation, the number of freeze-thaw events was 6, 3, and 2 under past, present, and future conditions, respectively. Moreover, according to the ERA5 reanalysis, only 1 freeze-thaw event was calculated. This is attributed to the fact that the climate model overestimates significantly the precipitation and the relative humidity compared to the ERA5 reanalysis. In conclusion, it is worth mentioning that both the climate-based and the material response-based indices define a decreasing trend of the frost damage risk of historic brick-made walls due to climate change. The use of the material response-based index is suggested for a more accurate assessment of the frost damage which can further support proper adaptation measures. Finally, the quality of the results can be improved by using climate data from more climate models and applying bias correction or morphing methodologies on the climate files to avoid systematic errors.

How to cite: Choidis, P. and Kraniotis, D.: Climate-based and material response-based approaches for the impact assessment of climate change on the frost damage of historic brick walls in Tønsberg, Norway., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12070, https://doi.org/10.5194/egusphere-egu22-12070, 2022.

Predictions forecast changes in climate that may affect cultural heritage in the future. Not only the underwater cultural heritage will become exposed, but also our land tangible cultural heritage will be submerged: entire nations and their cultural heritage may disappear, losing their identity as nations, countries, and communities. In fact, climate change has the potential to increase the sea level enough by 2100 to inundate 136 sites considered by UNESCO as cultural and historical treasures.

This presentation will examine the specific climate changes that oceans will most likely suffer and how they will probably affect tangible underwater cultural heritage, analysing how the changes will affect every possible material that can be found in a submerged archaeological site. It will also explore cases of heritage that are already suffering the consequences examining two future scenarios: how climate change may disturb underwater cultural heritage, and how land cultural heritage may change its label and subsequently become underwater cultural heritage. Lastly, the presentation will propose a new partnership natural/cultural resources and the qualification of cultural heritage as a natural resource for its preservation, establishing the same common measures for both heritage against climate change.

How to cite: Pérez Álvaro, E.: Climate change: a threat to underwater cultural heritage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-107, https://doi.org/10.5194/egusphere-egu22-107, 2022.

This contribution presents the work of research and technical development for designing a novel method for monitoring and predicting the weathering of cultural heritage, in particular of stones and timber used historically as building materials.
An apparatus for long-term field tests was designed in its hardware and software components with a twofold application:

• Exposure of a set of selected stone and wood specimens to natural weathering, at different orientations (North, South, and horizontal plane) and environmental settings (Italy and Norway).
• Non-stop acquisition of microclimate data series at different resolutions, down to the scale of the specimen surface, completed by datasets of regional stations of environmental monitoring.

Complementary laboratory analyses aim at setting a reference point for the state of conservation of each material before the exposure tests, and monitoring the changes of surface recession/topography (by 3D optical profilometry), thus reconstructing the relevant deterioration trends.
Within the framework of the EU-funded project HYPERION, this novel experimental approach is expected to help assessing the interaction of building materials with the environment and their weathering constrained by microclimate and climate variability; combining climate model simulations, the stresses brought about by climate change can also be assessed. The findings might represent a source of precious information for the activities and decision-making protocols of the stakeholders involved in the protection of cultural heritage.

How to cite: Germinario, L., Coletti, C., Choidis, P., Kraniotis, D., Maritan, L., Sassi, R., Tositti, L., and Mazzoli, C.: Developing a new method for long-term monitoring of the weathering of historical building materials, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5898, https://doi.org/10.5194/egusphere-egu22-5898, 2022.

Dust is one of the main pollutants that settle on historic structures and cause the blackening of stone surfaces. The stone facades of historic buildings became dark, and besides its aesthetic alteration, dust deposition and subsequent chemical reactions led to the deterioration of the construction material. The composition of dust changes in time due to climate change, clean air acts and changes in transportation, industrial activities and heat. The present study tries to detect the temporal changes in the composition of dust by using a stone buildings as dust traps in Budapest. The studied historic building is more than one hundred years old, and no façade cleaning was done in the past century. Visual inspection of the city centre building suggested that dust accumulation show a distinct pattern representing differences in the vertical profile in terms of thickness and colour. Dust samples were collected from layer to layer representing newly settled and historical dust. Scaffolds were made to reach the various elevations of the building facades. Besides the dust, host rock samples were also picked to detect textural and compositional changes of the porous oolitic limestone material. The textural-mineralogical analyses (XRD, SEM) and chemical compositional tests (XRF, LA-ICP-MS) provide evidence of changes in composition of dust with time. In all host rock samples, gypsum was detected but in various proportions. Good correlations were also found between water-soluble calcium and gypsum content and between sulphate and gypsum content both for black crusts and host rocks, forming two distinct fields in calcium vs gypsum and sulphate vs gypsum graphs. Gypsum was also found in the dust either as a primary or as a secondary mineral phase. Metals, transition metals and water-soluble ions also occur in various concentrations in different layers of dust. The detected elements primarily include  Fe, Mn, Zn, Cu, Cr, Pb, Ni. From soluble salts, chloride, nitrate and sulphate were also detected. The changes in elemental and ionic concentrations reflect temporal changes in dust composition and provide indirect evidence for air quality changes and air pollution levels.

How to cite: Török, Á.: Compositional changes of settling dust in time on buildings in Budapest: centennial evidence of air pollution trends, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12113, https://doi.org/10.5194/egusphere-egu22-12113, 2022.

Climate change has been proved to have negative impacts on historic areas hosting cultural heritage sites and monuments, which in turn yields significant adverse impacts on local economies, societies, and even politics. The first and necessary step of the process of confrontation of this challenge is the early detection and recording of the on-site inflicted damage by a monitoring tool. In order to achieve that, we developed a dedicated mobile application that aims to assist the assessment of the resilience and the deterioration of the historic areas and the potential impacts due to various hazards. Citizens and local authorities worldwide can directly use the developed application on their mobile phones to acquire photos of on-site damages and submit short reports based on them. This software component has been designed and developed in the context of the European project entitled “HYPERION”, which aims to deliver an integrated resilience assessment platform, addressing multi-hazard risk understanding, faster and efficient response, and sustainable reconstruction of historic areas.

With this application, we aim to create a user-friendly application with the latest user interface and usability issues/trends which is focused on museum enthusiasts and active citizens’ or travelers’ needs. It’s important to put the users of this targeted group at the center of our efforts and by understanding their needs to create an intuitive application for them and at the same time a useful tool for the local authorities.

Users download the application from the Google or Apple App store and they log in or create an account in the application through the PLUGGY platform, which was developed in the context of the “PLUGGY” European project. The main function of the application is to create and post an asset using PLUGGY’s REST API. An Asset is an elementary unit of content in PLUGGY, a media file with an identified owner, a title, a description, a set of tags, and a license, which specifies how this file can be reused. Initially, the user’s location is detected via GPS and corrected in case of miscalculation. The user is then prompted to select a photo (or directly to take a snapshot) that depicts the damage of a monument. To complete the creation of the asset, the user will also need to select a title that will accompany the photo, and some tags, not only for a better description of the event but also for correlation with other assets or exhibition points that already exist in PLUGGY.

The developed mobile application gives voice to citizens and encourages them to provide direct feedback to the relevant cultural authorities, in order to assist them in assessing the deterioration of the cultural heritage sites and determining the needed reconstruction actions. As a result, the communities can have a major role in the safeguard of their cultural heritage.

How to cite: Krommyda, M., Mitro, N., Georgiou, K., Nousis, V., and Amditis, A.: A Communities Engagement Mobile Application for Assessing the Resilience and Deterioration of Cultural Heritage Monuments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3476, https://doi.org/10.5194/egusphere-egu22-3476, 2022.

Salt weathering is a complex and active area of research, with implications for tangible cultural heritage worldwide. A preventive conservation approach is often taken to limit salt crystallisation cycles, which requires an understanding of the relative risks of scenarios and their respective heritage characteristics, salts present, and the climate, including climate change. Equilibrium relative humidity is an important property that indicates this risk: typically, it is represented by specific RH% and temperature derived from a single salt. The behaviour of single salts does not accurately represent the behaviour of salt mixtures, which are far more common in cultural heritage contexts. To address this, 11412 salt mixtures present in the built environment have been analysed using the ECOS/Runsalt model to predict their mixture-based mutual relative humidity of crystallisation and deliquescence points, the salt mixture composition, as well as the relative humidity of crystallisation and deliquescence for individual salts in the mixtures. This dataset, although sampled primarily from Belgian cultural heritage sites, is representative of the general classes of salt mixtures found in the built environment globally. This analysis represents an important step in developing a generalised statistical method for parameterising environmental time series data for salt weathering risk within climate change scenarios, as well as progressing fundamental knowledge on the behaviour of salt mixtures in built cultural heritage.

How to cite: Orr, S. A., Godts, S., and De Kock, T.: A data-driven approach to understanding the equilibria behaviour of salt mixtures in built cultural heritage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5264, https://doi.org/10.5194/egusphere-egu22-5264, 2022.

Water plays a vital role in the deterioration and conservation of built heritage and management problems might be aggravated by climate change. However, there is as yet no overarching framework for understanding the processes and impacts of water interacting with building materials. The term 'Heritage Hydrology' is a holistic way of conceptualising the flows and stores of water involved in deterioration of built and rock-hewn heritage. We distinguish the following basic types: (a) stone-built buildings, (b) ruins and free-standing walls, and (c) rock-hewn sites which include carved rock art and large rock sculptures. We focus on a key knowledge gap: The spatial and temporal characteristics of water flows/stores and the challenges of using currently available techniques to provide information on these characteristics.

In our selective review we provide examples of spatio-temporal patterns of moisture in stonework at different scales. We raise six key points about the state of research on heritage hydrology, from which we develop a future research agenda. (1) Three characteristics of moisture regimes are important to deterioration, i.e. presence, fluctuations and saturation thresholds. (2) There is a wide range of different heritage hydrological settings ranging from masonry building walls to natural rock slopes, and as yet no clear understanding of the commonalities vs specificities of these different settings. (3) While there is now a wide array of techniques available to measure and monitor moisture regimes in lab and field settings, the understanding of how comparable different measurement approaches are is still lacking. (4) There are now many measurements of the spatial patterning of moisture, but lack of clarity about the causes of these patterns. (5) There has been less research focusing on the temporal dynamics of moisture on heritage walls than on spatial patterns. (6) Studies combining measurement and modelling have proved particularly useful.

A research agenda for the future for heritage hydrology should focus on addressing the following broad questions: What are the best combinations of methods available to measure and model spatio-temporal patterns in moisture on built and rock-hewn heritage? What are the major factors controlling spatio-temporal patterns in moisture, also considering climatic changes? Which spatio-temporal patterns in moisture are most important for driving deterioration, and how do their respective scales interact? Tackling these research questions requires a coordinated approach, linking different research teams and methodologies. It should be based on a combination of data collected through laboratory experiments, detailed studies of test walls, and instrumented sections of walls at heritage sites. It should explore the causes and consequences of moisture regimes which provide fundamental links between climate and the deterioration of built and rock-hewn heritage.

How to cite: Sass, O. and Viles, H.: Heritage hydrology: A conceptual framework for understanding water fluxes and storage in built and rock-hewn heritage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10024, https://doi.org/10.5194/egusphere-egu22-10024, 2022.

Tuff is rich in color and is used as a stone material, and it is also a rock that forms a unique landscape in Japan, a volcanic country. However, since it is generally a fragile rock, it is susceptible to weathering and deterioration. The present study conducted an experiment to confirm the effectiveness of the surface protectant using tuff with different physical characteristics. Sodium sulfate aqueous solution was used to determine the effectiveness of protective agent application for 5 types of tuff (Oya stone, Nikka stone, Ashino stone, Tatsuyama stone, Towada stone) An experiment was conducted in which the lower 3 cm of a 5 cm × 5 cm × 15 cm specimen that had been oven-dried at 110 ° C was immersed in a salt solution, and 20 ° C-40 ° C was repeated for up to 20 cycles in a 48-hour cycle. When the weight and P-wave velocity of each specimen were measured every cycle, the solution reached the surface of the uncoated stone material for comparison, salt crystals were deposited. The surface of the specimen was peeled off, and the P-wave velocity gradually decreased.  On the other hand, in the stone material coated with the protective agent, salt crystallization was not observed even when the solution reached the top surface shortly after the start of the experiment.  The P wave velocity did not decrease, despite cracks occurred as the experiment progressed. As a result, the P-wave velocity began to decrease and the surface layer fell off. In Ashino and Tatsuyama stones, the coated specimens were more severely destroyed than the uncoated specimens. In Oya stone and Towada stone, which contain clay minerals (miso) in the form of patches, crushing proceeded from the miso part. This experiment suggests that the effect of the protective agent may depend on the rock structure and the pore diameter. In other words, for rocks containing miso, the use of a protective agent is likely to increase deterioration regardless of the pore structure. For rocks with a large proportion of micropores and low durability against salt weathering, the use of a protective agent is used. Therefore, the start time of surface exfoliation can be delayed. In addition, in rocks with a large proportion of large gaps (> 10-0.5 μm), even if crystallization occurs on the surface of the specimen. The  peeling does not occur for a while, but the protective agent penetrates deep into the thick protective agent penetration area. It is considered that the crystallization of the salt occurs more internally and the deterioration is more severe than it should be. 

How to cite: Oguchi, C. and Ikeda, Y.: Influence of rock pore structure on the protective coating against weathering, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5806, https://doi.org/10.5194/egusphere-egu22-5806, 2022.

This study aims to characterise the decay due to black patinas of Santalla de Bóveda Monument (Lugo, Northwest of Galicia, Spain).

Manganese is one of the most abundant elements on Earth, and the granite on which Santalla de Bóveda Monument was built (used as building material of the monument) has considerable amounts of Manganese. This monument shows black patinas on the surface of its building materials (mortars and granites).

Mortars and granite with Mn-rich black patinas were analysed in their chemical, mineralogical and petrographical properties (polarizing and scanning electron microscopes, X-ray diffraction and X-ray fluorescence). In addition, the water from springs near the monument was analysed.

According to the experimental study results, it was observed that rich Mn-oxide crusts are presumably induced by bacteria. That is, the oxidation of Mn fuels the growth of chemolithoautotrophic microorganisms, which need water to live. These patinas of biogenic Mn-oxide minerals presented different shapes, nano-dimensions, with low degree of crystallinity, and appear to be composed of manganese oxides such as birnessite, ramsdellite and groutellite. They were associated with large amounts of extracellular polymeric substances exuded by filamentous bacterial communities, which serve as nuclei for preferential precipitation of manganese oxides on the extracellular sheaths, as seen in scanning electron microscope analyses.

Mn required for patina formation likely derives from the reductive dissolution in water of Mn-rich minerals, as suggested by the mineralogy and chemistry of Mn-rich phases present in the building granite and mortars. Mn migrates to the exposed surface of building materials, where they are re-oxidized via biological processes. Patinas developing over time result from the alternation of wetting-reducing and drying-oxidizing cycles.

Water absorption, dampness and black patinas are among the most common and critical problems when it comes to decay of both cultural heritage and modern buildings. The climate and specifically the humidity are determinant for the development of Mn-rich black patinas. Results revealed that chemical composition and porosity played a major role in the development of biological activity that generates the black patinas of manganese oxides on mortars and granite.

How to cite: Freire-Lista, D. M., Blanco-Rotea, R., Costa, M. D. R., and Sanjurjo-Sánchez, J.: Mn-rich Black Patina Formation on Built Heritage in Humid Areas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8670, https://doi.org/10.5194/egusphere-egu22-8670, 2022.

During the 21^st Century, climate change and improving air quality will alter biological communities and their influence on building stones. While air pollution used to be a principal factor of stone deterioration, it is diminishing in many parts of the world. These environmental changes affect the aesthetics of building stones, and fewer black gypsum crusts will form, while more biological-induced discolorations could occur. Within the British Isles, it resulted in the “greening” of monuments after increased algal growth. Besides aesthetical damage, the formation of biofilms could affect water transport and retention. Changes in the water-stone relationship should be studied in detail because moisture is the most significant facilitator of stone alteration, leading to physical, chemical and further biological weathering.

This topic was intensely studied on soils. However, knowledge of the effect of biofilms on water transport and retention of stones is limited. For this reason, three porous natural building stones: Ernzen, Euville and Savonnières, were biofouled at the outer surface with the cyanobacteria Phormidium autumnale. The colonization was estimated by spectrophotometry, and their relationship with the stones was studied by Scanning Electron Microscopy (SEM), Environmental SEM (ESEM) and optical microscopy on thin sections. Based on the European standards, the water transport properties were determined of biofouled and untreated samples.

Microscopy showed that the biofilms covered the surface while they spanned over and closed numerous pores. They had a measurable effect on water transport and retention and reduced the rate of capillary water absorption and drying in combination with higher moisture content after (vapor) sorption. Moreover, the biofilms changed the surface wettability and induced near hydrophobic conditions in a dry state while no effect was measured on the water vapor diffusion and air permeability. These changes can alter the material properties and other processes like salt weathering and freeze-thaw damage. As swelling and shrinkage were observed by ESEM, the properties and physical effects of biofilms are expected to change with fluctuating relative humidity.

How to cite: Schröer, L., De Kock, T., Godts, S., Boon, N., and Cnudde, V.: The influence of biofouling on water transport inside porous stones, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5301, https://doi.org/10.5194/egusphere-egu22-5301, 2022.