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The old mining city of Guanajuato in middle Mexico preserves one of the most important historical legacies in colonial buildings, the UNESCO declared the city World Heritage Site in 1988. Practically all the colonial constructions were built with natural stones from the neighbourhood, of which stands a greenish to reddish vulcanite, called Loseros...
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... Variations of physical and mechanical properties of the KZ11-KZ12 sample after ageing test cycles (WD: Wet-Dry; FT: Freeze-Thaw; SC: Salt-Crystallization). b Effects of ageing tests on the ignimbrites of the samples with uniform and homogeneous distribution of the lithic grains is higher than those of the samples with the lithic grains varying in length and irregularly distributed in the rock matrix.Several researchers[18,60,69,96,107,119] have tried to develop empirical methods to estimate the uniaxial compressive strength of volcanic rocks by using index properties such as effective porosity, sonic velocity, point load strength index, Los Angeles abrasion, Schmidt hammer and slake durability tests ...
Cappadocia in Turkey is an important region with emphasis on ethnic and historic structures and geological features. Because of volcanic eruptions, ash flow materials deposited at different levels. These different colored ignimbrite levels have a wide range of geomechanical properties. In the region, the Kızılkaya ignimbrite covers a very large area and is frequently used as building dimension stone in for the restoration of old historical buildings such as churches, caravansaries and mosques as well as new buildings. It contains tuffaceous matrix with some minerals and rock fragments. The rock has variable character. In this study, the relationship between petrographic and physico-mechanical properties of the Kızılkaya ignimbrite was investigated. Rate of change between uniaxial compressive strength and the other index properties of the rock was statistically examined utilizing multiple regression analysis (MRA) and Artificial Neural Network (ANN) methods. The study has shown that uniaxial compressive strength (UCS) of the ignimbrite can be successfully estimated by the use of dry unit weight, effective porosity, sonic velocity, and grain matrix ratio (GMR) parameters. A new UCS prediction equation is proposed in this paper for the ignimbrite with variable character. Since properties of the ignimbrite at different distances from the eruption area changes significantly, the approach presented in this study can be considered for the ignimbrites especially covering a large area with different welding degrees and grains.
... Along the same lines is the research of Akin et al. (2017), evaluating the physical-mechanical properties of four different types of ignimbrites from the city of Ahlat. A large part of Mexico's architectural heritage is built with ignimbrites, which have been the subject of numerous research studies (Wedekind et al 2011;López-Doncel et al. 2013, 2016Siegesmund et al. 2022). ...
The objective of this study is to evaluate the petrophysical properties of four ignimbrites employed as dimension stones. The natural stone under study is produced in Tenerife Island (Spain) under the commercial brand name of Piedra Chasnera and are differentiated according to their chromatic variety into: brown, violet, grey and green. To assess the suitability for feasible applications, it is essential to have a comprehensive knowledge of its properties. In this respect, mineralogical, petrographic and chemical properties were obtained by X-ray diffraction (XRD), polarisation microscopy (POM) and X-ray fluorescence (XRF). According to the procedure described in the standardised methods, apparent density, open porosity, water absorption at atmospheric pressure, water absorption coefficient by capillary and ultrasound propagation velocity were measured. The four variants of ignimbrites were analysed and classified according to the results obtained. It was found that the properties vary depending on the depth of the stratigraphic volcanic level from which the stone is extracted. From the review of the published data, it can be seen that the test results are within the expected values for this lithotype. A comparison was also made with other types of dimensional stones. The correlation analysis shows that there is a high degree of correlation between the physical properties studied.
... ghter gray zones, sometimes purple and whitish. Distinct thin layers or bands are also visible showing greenish and reddish-brown laminations. Disseminated throughout the rock are numerous dark detrital clasts (black to reddish-brown) and millimeter-sized phenocrysts. These are embedded in a fine-grained ash-rich matrix containing abundant calcite.López-Doncel et al. (2013) identified two ...
Volcanic tuffs and sandstones have been used as natural building stones in the construction of monuments and buildings over the millennia of human history. Progressive weathering over time (e.g., temperature fluctuations, moisture uptake, variations in humidity, precipitation, the input of modern-day pollutants or salt crystallization) lead to damages in the internal structure of the stone. Scaling and layer-parallel flaking of rock fragments result from these types of damage-causing processes, especially when swellable clay minerals are present that lead to the generation of stresses in the rock fabric. Tuff and sandstone samples that exemplify these types of damages are investigated in this study, which were used in the construction of cultural heritage sites in Armenia, Mexico, Germany and Switzerland. Comparisons are made between these rock types considering that they show strong variations in fabric heterogeneity, grain sizes, mineralogical composition (e.g., swellable clay- and zeolite-bearing minerals), and visible macroscopic features such as depositional layering. Comprehensive investigations have been carried out that include detailed petrographic analyses, XRD analyses for the determination of the swellable and non-swellable clay fraction and minerals of the zeolite group, the cation exchange capacity (CEC), detailed SEM surveys for determining the type and localization of clays and zeolites in the rock fabric, as well as defining the petrophysical properties (e.g., porosity, capillary water uptake, water absorption, hydric expansion and mechanical properties). Moreover, this study explores the possible interaction between swellable clay minerals and zeolites (mordenite, heulandite/clinoptilolite) by conducting swelling experiments with salts and solvents and fluid-exchange experiments with and without the presence of zeolites. To explain the damages caused by the expansion in the tuffs and sandstones, two principle modes of moisture expansion are discussed when swellable clay minerals are present in the rock. These are dominantly inner or intracrystalline swelling, and secondarily, intercrystalline or osmotic swelling. When no swellable clay minerals are present, the study explains the damages in tuffs and sandstones as the result of disjoining pressure, where a high percentage of microporosity plays a pivotal role.
... These elements include building materials (such as stone ashlars, clay-based materials, stuccos) and the unique art pieces they enclose (sculptures, paintings, frescoes). In this context, partial water saturation of materials offers excellent conditions for deterioration: salt crystallization, microbial degradation, reduction of their mechanical strength, chemical weathering enhanced by the presence of CO 2 , etc. (e.g., [10,[13][14][15][16][17]). Particularly, salt weathering is an important damaging agent for buildings, considered one of the most common reasons porous building materials are deteriorated as it is found in most of the built heritage. ...
The Santo Domingo Diocesan School (Orihuela, SE Spain) is a singular case study that relates air quality monitoring and stone conservation. The monument suffers severe damage due to salt crystallization by rising damp, which is related to the indoor environment dynamics, high groundwater salt content, and microstructure, the building’s porous stone (biocalcarenite). Results revealed that 222Rn concentration in indoor air is low due to the building’s high ventilation rate, despite the medium-low geogenic radon potential in the area. Wavelets analysis showed that ventilation is caused by outdoor and indoor temperature variations and directly affects the 222Rn and CO2 dynamics inside the church. CO2, as well as relative humidity (RH), presented periodicities with intermediate frequencies (5–8 days) related to visits. These RH and temperature (T) variations intensified the salt damage by increasing the frequency of dissolution-crystallization cycles. The mineralogical characterization and geochemical calculations concluded that chlorides (halite and sylvite), sulfates (thenardite, epsomite, hexahydrite and aphthitalite) and nitrates (niter) present from dissolution forms to whiskers and hopper-type morphologies. This indicates high saturation values and, therefore, higher crystallization pressure values within the porous media of the biocalcarenite. On the contrary, the near-equilibrium crystal shape and incongruent precipitation reaction for humberstonite suggest a lower alteration for this salt on the building stone.
... Just to name a few, it has been observed in limestone blocks at the Jaen's Cathedral (Spain) (Fig. 1a-b) [62], ancient Egyptian limestone sculptures and stelae in the British Museum (London, UK), Metropolitan Museum (New York, USA) and Phoebe Hearst Museum (Berkeley, USA) [8,9], carved limestone rocks at the royal tomb of Seti I, Valley of the Kings, Luxor (Egypt) [67], or limestone rainscreen walls in a modern building in Valencia (Spain) [68]; in several types of sandstones, such as Villamayor [58,69] and Tarifa (Spain) (Fig. 1c-d) [47,48], Meules (France) [70], Portland Brownstone (USA) [10], Villarlod Molasse (Switzerland) [10], several German sandstones [49,71], Macigno sandstone (Italy) [46,72], Angkor Wat sandstone (Myanmar) [73,74] and Petra sandstone (Jordan) [75], as well as in sandstone used for roof tiling in NE Spain [76]; and very commonly, in volcaniclastic tuff stones [50]. This is for instance the case of tuffs making up the Moai sculptures in Rapa Nui (Easter Island) [45], Missions in California (USA) [77], ancient Roman and Ottoman constructions [78], as well as several monuments in central Europe [50,79,80] and Anatolia [50], including the Fairy Chimneys of Cappadocia (Turkey) [81], or some pre-Hispanic structures and colonial buildings in Mexico [82,83] and the Maya structures, sculptures and hieroglyphs in Copan (Honduras) (Fig. 1e, f) [51,84]. This phenomenon is rare in non-sedimentary stones such as igneous and metamorphic ones [85]. ...
Significant progress in the understanding of the different degradation processes affecting building and ornamental stone has taken place in recent decades. However, some weathering phenomena still are not fully understood, which hampers the development of effective stone conservation treatments. One of these cases, stone damage associated with the presence of swelling clays, is reviewed here. Swelling clays cause damage when subjected to wetting/drying cycles, commonly resulting in stone scaling, flaking, spalling, exfoliation and/or delamination. Examples of this damage process and the mechanisms proposed for its development, as well as the key factors that control its origin, evolution and severity are presented and discussed. Alternative or complementary processes that may also lead to stone damage due to expansion/contraction cycles are also discussed. Finally, conservation treatments applied to halt or minimize clay swelling damage are reviewed. It is shown that traditional conservation materials such as polymers and alkoxysilanes applied to protect and/or consolidate damaged clay-containing stones typically have little effectiveness. Alternative treatments based on the application of clay swelling inhibitors, and a novel green conservation approach based on bacterially-induced formation of CaCO3 cement and associated production of exopolymeric substances, recently proposed to prevent/control clay-related damage of tuff stone at the ancient Maya site of Copan, are presented and discussed.
... Further substantial influences on the results can be the different shape of the test specimens (e.g., cylinders react different to stress than cubes), the particular laboratory conditions (e.g., increased relative humidity), experimental procedure (e.g., different strain rates), and in the end human failure during testing, evaluation and documentation. It is also important to mention that tuffs, due to their depositional conditions and frequent directional fabric, often show strong directional dependence, as demonstrated by several authors (e.g., Colella et al. 2017;López-Doncel et al. 2013;Martin III et al. 1992;Pötzl et al. 2018a;Stück et al. 2008;Weiss et al. 2004), which, however, is not considered in many studies. To maintain a large and representative dataset, the most commonly published mean values of the technical parameters were therefore used for the statistical analyses. ...
Volcanic tuffs naturally show a strong heterogeneity in their petrography and petrophysical properties. The arrangement of the components in tuffs can create a very wide spectrum of porosities and fabrics, which in turn can lead to a highly differential weathering behavior. Considerable amounts of clay minerals and zeolites are common, and can contribute to a high sensitivity to expansional processes and salt crystallization. Understanding the influence of the rock properties on material behavior and durability can help to make predictions on future material behavior and evaluate the suitability of the material for construction purposes. This study presents the petrographic and petrophysical data of 15 selected tuffs and 513 tuffs from the literature used as building stones. Regression analysis show if parameters are comparable and if key parameters can be identified. Key parameters can potentially be used for the estimation of the material behavior, without the use of expensive analytics or weathering simulations.
... Further substantial influences on the results can be the different shape of the test specimens (e.g., cylinders react different to stress than cubes), the particular laboratory conditions (e.g., increased relative humidity), experimental procedure (e.g., different strain rates), and in the end human failure during testing, evaluation and documentation. It is also important to mention that tuffs, due to their depositional conditions and frequent directional fabric, often show strong directional dependence, as demonstrated by several authors (e.g., Colella et al. 2017;López-Doncel et al. 2013;Martin III et al. 1992;Pötzl et al. 2018a;Stück et al. 2008;Weiss et al. 2004), which, however, is not considered in many studies. To maintain a large and representative dataset, the most commonly published mean values of the technical parameters were therefore used for the statistical analyses. ...
Volcanic tuffs naturally show a strong heterogeneity in their petrography and petrophysical properties. The arrangement of the components in tuffs can create a very wide spectrum of porosities and fabrics, which in turn can lead to a highly differential weathering behavior. Considerable amounts of clay minerals and zeolites are common, and can contribute to a high sensitivity to expansional processes and salt crystallization. Understanding the influence of the rock properties on material behavior and durability can help to make predictions on future material behavior and evaluate the suitability of the material for construction purposes. This study presents the petrographic and petrophysical data of 15 selected tuffs and 513 tuffs from the literature used as building stones. Regression analysis show if parameters are comparable and if key parameters can be identified. Key parameters can potentially be used for the estimation of the material behavior, without the use of expensive analytics or weathering simulations.
... Condensate water appears in both building indoor and outdoor environments and can become critical depending on microclimate variations and pore structure and hygrothermal properties of the material. Water affects stone's strength and deformability and triggers salt and ice crystallisation, clay swelling, the development and proliferation of microorganisms, also increasing rock reactivity and the intensity of chemical weathering processes by the presence of CO 2 [4][5][6][7][8]. Particularly, the presence of water can become critical inside of monuments as building materials include indoor elements (such as stone ashlars, clay-based materials, stuccos) and the unique works of art they enclose (i.e.: sculptures, paintings, frescoes) [9]. ...
Condensate porosity in porous materials has a significant influence on comfort, energy consumption, and material’s strength and durability. The variation of the moisture content of the material for a given variation of relative humidity describes the moisture storage capacity and has to be determined experimentally through the water sorption isotherm. However, the characterisation of sorption isotherm is very time-consuming, mostly for high relative humidity conditions, which may cause experimental errors and reproducibility problems.
This paper aims to estimate experimental water condensate porosity using mercury intrusion porosimetry and nitrogen adsorption technique considering pores smaller than 0.1 μm for a wide range of porous sedimentary rock types with different petrographic characteristics. Particularly for nitrogen adsorption characterisation, we interpolated the pore volume using BJH method applied to the desorption branch. In the water adsorption test, condensate porosity is obtained with the maximum adsorbed water at RH = 100%.
The ratio between water condensate porosity and total porosity in the studied porous stones is important and varies from 2 to 38%. Nitrogen adsorption technique provides the best estimation of condensate porosity (R² = 0.979) and an effective estimation of water condensate porosity. The correlation between condensate porosity using MIP is moderate (R² = 0.892) and presents a wider dispersion for all the range of condensate porosity. A mathematical expression that fits the shape and curvature of the water isotherm was also analysed in terms of pore structure. These studies are scarce for porous stones and our results provide valuable information for these widely used construction and building material.
... To date, numerous studies focusing on various types of saturated rock have led to the conclusion that mechanical properties deteriorate as a result of the existence of water. The subjects of those studies included sandstone (Shakoor and Barefield 2009;Verstrynge et al. 2014;Zhou et al. 2019), mudstone (Erguler and Ulusay 2009;Jiang et al. 2014;Ewy 2014), limestone (Török and Vásárhelyi 2010;Gajićet al. 2011), and tuff (López-Doncel et al. 2013;Çelik et al. 2014). Apart from most research on argillaceous or large-porosity rock with strong water sensitivity, there are limited results regarding mechanical properties of saturated hard rocks with relatively dense structures (Lajtai et al. 1987;Masuda 2001;Mahmutoğlu 2006;Karakul and Ulusay 2013). ...
... Stress-strain diagrams recorded during uniaxial compression tests: (a) specimens obtained from sample DR1; (b) specimens obtained from sample DR2. -Doncel et al. 2013;Marcari et al. 2007) and average quality handmade bricks, (Alecci et al. 2016, Drougkas, Roca, andMolins 2016;Lourenço, Fernandes, and Castro 2010;Matysek and Witkowski 2016;Shu et al. 2017). In particular, the Desert Rose stone shares, with the tuff stones, mechanical properties that are not elevated and closely related to bulk density and porosity, in agreement with (López-Doncel et al. 2013). ...
... -Doncel et al. 2013;Marcari et al. 2007) and average quality handmade bricks, (Alecci et al. 2016, Drougkas, Roca, andMolins 2016;Lourenço, Fernandes, and Castro 2010;Matysek and Witkowski 2016;Shu et al. 2017). In particular, the Desert Rose stone shares, with the tuff stones, mechanical properties that are not elevated and closely related to bulk density and porosity, in agreement with (López-Doncel et al. 2013). Also, in (Lourenço, Fernandes, and Castro 2010), the mechanical parameters of handmade bricks, both new and old, present analogies with those obtained for Desert Rose stone, both in terms of values and dependence on physical properties. ...
In this paper, the unknown and peculiar construction technique employed in vernacular buildings of the Algerian region of Souf is addressed. Traditional architectures of this desert area are made of unusual building material, the Desert Rose stone. Also, typical buildings are covered with domes that outline a unique urban landscape included in the "Tentative List of UNESCO". To pursue coherent safeguarding policies, constructive techniques are investigated through in situ surveys, sampling, and laboratory analyses that enabled characterisation of local materials. Petrographic observations revealed remarkable cohesion between blocks and mortar, which explains the satisfactory behaviour of a masonry realised with very irregular stone blocks. A preliminary analysis of the structural behaviour of a representative dome is carried out employing both a FEM simulation and the static approach of limit analysis. The results allow an interpretation of the observed crack patterns that show widespread fractures along the diagonals of the domes.
