Displays

Different stone qualities in masonry walls cause considerable problems on masonry walls during restoration works. The properties of limestone show significant variations due to differences in sedimentary structures which are might not be visible at the scale of laboratory test specimens. Even at one quarry level, there could be major differences in properties due to the cross-bedding or tilted rock beds. Physical parameters of 3 typical types of porous limestone (fine-, medium-, coarse-grained) were studied under laboratory conditions in order to assess an explanation for variations in weathering forms on masonries of historical buildings. Laboratory experiments were performed to determine the bulk density, water absorption, apparent porosity, ultrasonic pulse velocity under dry and water-saturated conditions. Aim of this research is to find correlations between physical parameters of limestones and show considerable diversity in properties. Our results indicate that there is a relationship between dry and water-saturated bulk density vs. ultrasonic pulse velocity and dry and water-saturated bulk density vs. apparent porosity, respectively. It is well known that microstructure influences the damage mechanism of stones. Our research demonstrates that variations exist in the stone fabric even at quarry level, based on the samples of Sóskút quarry. The different limestone lithologies were used side by side in historical buildings; therefore our results help experts during restoration works in decay mapping of monuments.

How to cite: Papay, Z., Rozgonyi-Boissinot, N., and Török, Á.: The relationship between the bulk density, the apparent porosity and ultrasonic pulse velocity of highly porous limestone, examples from Hungary, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19585, https://doi.org/10.5194/egusphere-egu2020-19585, 2020.

Visual inspection of deterioration phenomena across the façades of a historical monument demonstrates the spatial variability of weathering processes. Multiple previous weathering simulation and exposure trials have been developed to investigate the connection between weathering processes and spatial variability of response. However, in landscape systems theory, stability is a function of both spatial and temporal components. Temporal sensitivity is a function of both the magnitude and frequency of formative events and the spatial sensitivity of the material.

One area of urban stone decay literature that requires further attention is the initial response of quarry ‘fresh’ material to emplacement within a building. Previous small-scale investigations have demonstrated that alteration commences within a few months to a year of emplacement. These early changes to the material will have a lasting influence upon the development of future weathering processes and their spatial distribution. The necessity to investigate both the spatial and temporal components of this transition, well suits the capabilities of spatiotemporal kriging tools.

The influence of aspect upon the initial alterations of the material’s properties are of significance to interpreting the weathering response to transition. Therefore, five sandstone blocks were placed within an exposure frame, located in South Belfast, for a duration of one year. One block was exposed to each of the four cardinal points whilst the fifth was positioned to represent a horizontal surface on a structure, such as a window sill or balustrade. Permeability measurements were recorded in a regular grid across the exposed surface of the block once a month, creating a data set that is both spatially and temporally dense. No previous studies have collected a similar quantity of points, across both space and time, to investigate weathering processes. The application of only spatial techniques proved to be inappropriate to fully interpret the complexity of the changing material properties. Use of spatiotemporal kriging allowed the modelling of the sample blocks to illustrate the changing material properties over time. The outcome of this work is the development of a better-informed understanding of the initial alteration of building stones placed within the urban environment. Additionally, the observed variance of the temporal component has improved our understanding of the nature of early episodic change within the stone decay system.

How to cite: Johnston, B., McKinley, J., and Warke, P.: Spatiotemporal investigation of material property changes in building stone following initial emplacement, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21284, https://doi.org/10.5194/egusphere-egu2020-21284, 2020.

Tuff stone, a porous pyroclastic rock, is a light and soft material. Hence, tuff is easy to handle and to transport. It is used as construction material in numerous historical buildings. Due to its high water absorption and retention potential, heterogeneous pore structure, and clay mineral content, tuff is highly sensitive to weathering by moisture expansion and salt crystallization [1; 2]. The search for a protective agent for tuff stone has been subject to scientific studies for several decades. Yet, due to the high variability and heterogeneity of tuff stone, no generally applicable means to protect tuff against weathering has been found to date. Instead, case specific solutions are developed to preserve historical buildings. Often it is necessary to remove weathered parts of the stone or exchange whole tuff ashlars to ensure the stability of the construction. Since tuff is a limited resource, it is crucial to find suitable protective agents that prolong the life-cycle of tuff stone to preserve historical buildings

To favourably influence water absorption, effective porosity, and the pore structure of tuff stone, a thorough impregnation of the stone with the protective agent is desirable. This can be achieved by the application of silica sol products, which are dispersions of colloidal amorphous silicon dioxide particles. The small particle sizes (between 10 and 100 nm) facilitate a high penetration depth. Despite of the promising results of several studies, colloidal silicas are rarely used as protective agents for tuff stone in the restauration practice [3; 4]. This may be due to the lack of long-term experiences with these materials. Furthermore, the performance of protective agents is closely related to the pore structure and chemical and mineralogical composition of the rock [5; 6]. To understand these interactions, further research is needed.

The aim of a current research project is to study the application of colloidal silica as protective agent for Weiberner tuff. In first tests, penetration depth and changes in the pore structure are analyzed. Furthermore, the influence of the treatment on the hygric and mechanical properties and on the durability of the stone is studied. The new data will contribute to a better understanding of tuff stone deterioration and conservation.

[1] Wedekind et al. (2013) Environ. Earth Sci. 69. [2] Pötzl et al. (2018) Environ. Earth Sci. 77. [3] Iucolano et al. (2019) Contr. Build. Mater. 202. [4] Zornoza-Indart & Lopez-Arce (2016) J. Cult. Herit. 18. [5] Török et al. (2007) Geol. Soc. London, Spec. Publ. 271. [6] Stück et al. (2008) Environ. Geol. 56.

How to cite: Stuff, M., Rübner, K., Prinz, C., Rische, N., Chronz, M., and Kühne, H.-C.: Weathering and conservation of tuff stone , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18178, https://doi.org/10.5194/egusphere-egu2020-18178, 2020.

The possibility of using geopolymers to fill gaps/lacunae in glazed ceramic tiles (azulejos) has been studied. Since the 15^th century, glazed ceramic tiles are characteristic elements of the Portuguese architectural heritage and their use as external rendering elements has made them prone to degradation. On the other hand, civil construction is a sector with a high consumption of natural resources and CO₂ emissions. In order to respond a necessary increase of sustainability in conservation/restoration processes, it is important to create/use sustainable repair materials that also ensure compatibility and durability of interventions. Geopolymers were studied as a potential sustainable and compatible repair material. Two commercial metakaolins ARGICAL-M 1200S and ARGICAL-M 1000 were used as precursors in geopolymer pastes and tested. The purpose of this research was to assess the potential of geopolymers in the restoration of the glazed ceramic tiles, both in the filling of gaps and the bonding of ceramic fragments. The physical, chemical and mineralogical analyses of these materials were performed. Additionally, in order to evaluate possible use in conservation interventions, tile lacunae filling, glazing reintegration and bonding of ceramic fragments were studied. Several tests were performed in order to analyse the compatibility and durability of the designed geopolymers and the ceramic/geopolymer system. The results suggest that the geopolymers had a better performance in the bonding of ceramic fragments and can have potential to be applied in the conservation and restoration of tile facades. Thus, as a general conclusion, it was possible to develop sustainable materials to apply in conservation of buildings facades.

How to cite: Rocha, F., Moutinho, S., Costa, C., Andrejkovičová, S., Mariz, L., Sequeira, C., Terroso, D., and Velosa, A.: Metakaolin geopolymers applied in the conservation of tile facades: a Portuguese case study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7524, https://doi.org/10.5194/egusphere-egu2020-7524, 2020.

The mechanical behavior of a natural stone ventilated facade is inevitably based on the correct execution of both anchoring elements, stone cladding and enclosure support, either with brick masonry walls or reinforced concrete walls. In the case studied in the present work, the origin of the damages on the facade of a building located in Lisbon has been analyzed, where stone detachments were starting to occur. This enclosure is a ventilated facade cladded with Portuguese limestone Lioz slabs. Non-destructive borescope analysis of the metallic anchoring system employed was performed, as well as X-Ray fluorescence laboratory analysis (FRX) for chemical characterization of the anchoring material. Results obtained demonstrated the problem cause on the stone facade due to incorrect metallic anchoring selection and poor execution combined with stress corrosion effect, especially for slabs with larger dimensions.

How to cite: Pires de Almeida Ribeiro, V.: Durability of a ventilated stone facade: A case study of a limestone facade affected by the corrosion of the anchorage system , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3755, https://doi.org/10.5194/egusphere-egu2020-3755, 2020.

How to cite: Belhaj, S., Jaouda, I., Souidi, H., and Aqil, M.: Chemical and geotechnical analysis of the mortar and rammed earth from merinid walls of the Morrocan historical monument Chellah-Rabat for detection of alteration products and the origin of the original materials used., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-837, https://doi.org/10.5194/egusphere-egu2020-837, 2020.

Over the past few decades, the construction industry has focused on sustainable, environmentally friendly and easily recyclable materials. The objective of this work is to characterize and enhance the thermal conductivity, mechanical strength and setting time of a composite material based on plaster and lime. This material is designed for use in plasters.

Two types of gypsum are studied, the first one belongs to the Safi basin, the second one characterizes the High Atlas of Marrakech and precisely Douar Tafza. Geologically speaking, the two sites have many similarities. They are characterized by a Meso-Cenozoic age coverage covering a deformed Paleozoic age basement.

The characterization of the plaster's raw material, gypsum, was necessary to determine its physical and geotechnical properties, mineralogy, thermal behaviour and microscopic structure. Several analyses have been developed such as: pycnometer density measurement, X-ray diffraction, infrared spectroscopy and scanning electron microscopy.

We made samples, of standardized dimensions, of two mixtures based on the two types of plaster reinforced by the addition of two types of lime from different localities. The latter are from Marrakech and the Agadir region. The water/plaster mass ratio was set at 0.75 and the addition of lime was achieved by increasing its percentage in slices by 12.5% and up to 50%.

The reinforcement of plaster with lime has enhanced its thermal and mechanical properties and setting time. The measurements show that the addition of lime has reduced the thermal conductivity and increased the mechanical strength of both types of plaster. In addition, following the addition of lime, the setting time has decreased and the basicity of the material has increased. Noting that the intrinsic properties of the raw material influence the mechanical and thermal properties of the material.

Keywords:   plaster, enhancement, properties, mechanical, thermal, Morocco

How to cite: baba, I., Ibnoussina, M., and Witam, O.: Identification and enhancement of the thermal and mechanical properties of two types of plasters successively derived from gypsum: from the Safi basin and the High Atlas of Marrakech, Morocco, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-886, https://doi.org/10.5194/egusphere-egu2020-886, 2020.

Mobile processing and use of short-transported aggregates

Svein Willy Danielsen¹⁾ and Tero Onnela²⁾

¹⁾ Geomaterials Consultant

²⁾ Metso Minerals

Aggregates are major constituents in construction, the global request for which approaches some 22 billion tonnes per year. Some major challenges follow; first of all the dependency on geological conditions and the availability of resources; secondly the traffic, emissions and energy use connected with transportation; thirdly the technology of utilising resources with a variety of properties to meet user requirements; and finally – getting more awareness – the land use conflicts and environmental impact of the aggregate and quarrying industry, and the need for making these activities sustainable. 

Geological resources are non-renewable, which e.g. can be seen in the rapid depletion of natural sand/gravel deposits: Most development in the aggregate sector is now focusing on crushed/manufactured materials. This causes increasing awareness along with environmental impact; conflicts of interest concerning land-use; sustainability in mass balance; and not least – increasing transport distances required to get the materials to the places of use.

The principle of a Best Available Concept (BAC) for aggregate production and use was introduced by Danielsen and Kuznetsova (2016 Geological Society Special Publication 416, pp 50-70), working with four essential phases: Inventory and planning, Quarrying and production, Use of aggregates, and Reclamation of mined-out areas. Important in such a concept is the use of novel LCC and LCA tools to enable the calculation of environmental and economic consequences of decisions.

The development of concepts and technologies to utilise local aggregates on a short-travel basis, is an important part of this. A major Norwegian research project Local Use of Rock Materials, lead by SINTEF and sponsored by industry and the Research Council, has just been concluded. One aim of such a development was to obtain production processes on mobile platforms to offer on-the-run solutions that can greatly reduce the need for transport to and from site, make more tolerant user techniques of excavated or secondary rock materials, and not least, contribute to a significant improvement of mass balance. A comprehensive report on this theme has been prepared by the present authors.

Aggregates should be prioritized based on geological conditions in a bottom-up concept. This means that when considering local and/or short-travelled alternatives, the design and engineering solution should be based on the aggregates available – not the other way around. The geological differences and the often unpredictable variations are clearly among the major challenges for a short-travelled solution. The report highlights the aggregate technology triangle in order to see the geology – production – application interconnection, for the creation of good solutions

The set of novel processing technologies available, present the opportunities to transform theoretical knowledge into practical aggregate production. Especially, the portable processing equipment and the novel technology for crushing and sorting opens for solutions to produce purpose adapted, local/short-travelled aggregates. The report suggests processing examples for different user-purpose. Several flow-sheets for mobile processing of different kinds of product are presented and discussed.

How to cite: Danielsen, S. W. and Onnela, T.: Mobile processing and use of short-transported aggregates , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7808, https://doi.org/10.5194/egusphere-egu2020-7808, 2020.

Waste concrete is the most predominant constituent material among construction and demolition waste. Recycling of this material could minimize landfilled waste and mineral resources depletion. This study investigates, in laboratory scale, the production of upgraded recycled concrete aggregates, suitable for the replacement of primary (crushed limestone sand) used in cement mortars, by means of selective crushing and autogenous grinding. These particle size reduction techniques, compared to traditional crushing/grinding, have the potential to remove the brittle cement paste from the aggregates, thus significantly improving their quality. The granulometry, the density, the water absorption (EN 13755) and the flow coefficient (EN 933-6) of the produced upgraded sand was determined and compared to crushed limestone sand. Subsequently, cement mortar specimens were manufactured using upgraded aggregates for total replacement of crushed limestone sand. Specimens were tested for their compressive and flexural strength (EN 196-1), density and water absorption. Results indicated that the upgraded recycled sand produced through the selective crushing and autogenous grinding processes had improved properties compared to the one produced by conventional crushing processes (flexural and compressive strength of cement mortar specimens were increased by 29% and 7%, respectively). However, the quality of the upgraded sand is lower than that of the primary crushed limestone. To further explore the issue, it is planned to investigate in more detail the process of autogenous grinding and to investigate the use of other selective aggregate-cement paste liberation technologies.

How to cite: Galetakis, M., Soultana, A., and Daskalakis, T.: Production of upgraded recycled aggregates from construction and demolition waste for replacement of primary sand in cement mortars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5137, https://doi.org/10.5194/egusphere-egu2020-5137, 2020.

Nowadays, the production of constructional materials requires raw materials obtained through extractive activities that often imply different environmental impacts. In a perspective of a growing sensitivity towards a responsible use of natural resources the attention to materials coming from waste is focused. The waste from the municipal thermovalorization plants can be suitable for this applications, and after moderate and sustainable treatments, can find a role of raw material-second in the construction of works, reducing the need to find additional natural resources and related problems for disposal or storage. The present study aims to explore the possibility of promoting inertization (i.e. reducing the BA’s release in water of environmentally dangerous chemical species below the legal thresholds) of as large a fraction of BA as possible, using ashes from one of the municipal waste incineration plants of Northern Italy, and exploiting byproducts of the incineration cycle, i.e. the spared steam from turbines, which produce electricity, and carbon dioxide from combustion fumes. The treatments discussed are as a function of the particle size (s).  BA are partitioned into three main classes, determined by previous studies s ≥ 4.75, 4.75 > s ≥ 1, s < 1 mm; %. The BA fraction with 4.75 > s ≥ 1 mm was further divided into two portions to optimize the steam washing process: 4.75 > s ≥ 2 mm and  2 > s ≥ 1 mm. BA with s > 4.75 mm are treated with steam washing only. In fact, although they do not contain high concentrations of heavy metals, they largely surpass the Italian legislation thresholds related to the occurrence of chlorides and sulfates. Steam is generally available from modern incineration plants in a considerable amount, and it is more effective than water in removing a variety of impurities/low-crystallinity fragments from the surface of coarse grains. Inertization of BA with 4.75 > s ≥ 1 is investigated by means of both steam washing and accelerated carbonation, to optimize the combination of these methods and expand as much as possible the s-range that requires steam washing only.  As to the BA fraction with s < 1 mm, whose heavy metals content is likely larger than elsewhere, steam washing is of difficult application and therefore we resort to accelerated carbonation.

How to cite: Caviglia, C., Destefanis, E., Bernasconi, D., Pastero, L., Confalonieri, G., Corazzari, I., Turci, F., Bonadiman, C., Tassinari, R., and Pavese, A.: Environmental managing of bottom ashes from municipal thermovalorization waste for civil applications, as a function of particle size, based on steam washing, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17649, https://doi.org/10.5194/egusphere-egu2020-17649, 2020.

Ordinary cement resulting from the reaction of a calcium aluminosilicate-rich powder plus water works as binding matrix in modern concrete. The design of alternative binders is currently a global challenge in order to reduce the environmental footprint associated to the ordinary cement production. Alkali-activated calcined clay materials (AAccMs) represent a class of sustainable binders made of the blending of a concentrated alkaline solution and a solid fraction with thermally treated phyllosilicates. Metakaolin produced by the heat treatment at temperatures between 550-900°C of kaolinite, has long fascinated the scientific community for its high reactivity at high-pH stage. However, the higher costs of commercial metakaolin push towards the use of locally available low-purity kaolinitic soils, such as laterite covers, as potential raw materials to produce low-CO₂ cements with the benefit of reducing the cost of feedstock transportation.

The work is focused on the role of triethanolamine (TEA) and triisopropanolamine (TIPA) on the reaction kinetics of ordinary cement pastes and AAccMs, the latter with different aluminosilicate reactive fraction and degree of purity. TEA and TIPA are tertiary alkanolamines with a developed molecular structure. It has been assessed that low equal dosages of alkanolamines introduced in advance to the mixing water for cement hydration can act on the setting time and the degree of cement reaction. These chemical compounds, and above all TIPA, are recognized as iron-chelating agents that can increase the dissolution rate of ferric ions from the ferroaluminate phase of cement and promote their complexation. Moreover, alkanolamines can also form water-soluble calcium-complexes that may influence the hydration kinetics of calcium-silicate phases and the precipitation of hydrates in the binder microstructure.

The raw and the reacted materials are characterized by X-ray diffraction (XRD) and the kinetic pathways are followed with the aid of a semi-adiabatic calorimetry. The dissolution-precipitation steps of hydration in aqueous and alkaline solutions are subsequently simulated. Ordinary cement is used to clarify the role of alkanolamines as hardening accelerators. Afterwards, the kinetics of alkali-based pastes of high-purity metakaolin and a Fe-rich laterite, both blended with waste marble powder, are compared with the aim of assessing the formation of calcium-complexes in solution and any change in the kinetics due to the presence of iron in the raw material. Mechanical strength tests are performed to make clear the beneficial or detrimental effect of TEA and TIPA on the materials.

How to cite: Mascarin, L., Valentini, L., Dalconi, M. C., Garbin, E., and Artioli, G.: Role of alkanolamines in ordinary and alternative cement systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10013, https://doi.org/10.5194/egusphere-egu2020-10013, 2020.

The consumption of natural resources in various industrial sectors has caused significant environmental issues to the atmosphere through emission and energy cost due to the extraction and transportation of the materials, along with the availability and long-term damage to the natural resources. In order to address this issue, various solutions have been provided to reduce the amount of consumed natural resources by replacing them with alternative materials such as plastic waste and plastic, as a burden to the environment, is one of those materials being well explored by other researchers due to its worldwide applications and destructive impacts on nature.

The industrial sectors, as massive consumers of natural resources and producers of plastic waste, have shown a continuous responsibility towards innovative alternatives for natural resources. In this regard, plastic materials such as Polyvinyl, Polystyrene, Polyethylene and Polypropylene have been investigated to replace coarse and fine aggregates in the construction without compromising the performance of the concrete mix.

This study aims to investigate the influence of Polypropylene as a fine aggregate replacement on the compressive and tensile strength of concrete cylinder samples after 28 days of curing and assess the impact of temperature on thermal properties of the 28 days cured samples.

How to cite: Keihani, R. and Bahadori-Jahromi, A.: Investigate the influence of Polypropylene as fine Aggregate Replacement on the mechanical and thermal properties of the concrete mix , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21782, https://doi.org/10.5194/egusphere-egu2020-21782, 2020.

This research investigates as chemical and mineralogical properties can affect degradation of concrete, made using secondary aggregates derived from recycled, in the enforcement of Waste Framework Directive (WFD) 2008/98/EC. High volumes of C&D require the use of waste in various productive contexts. The utilisation of secondary materials derived from CDW recycling in flooring of industrial warehouse can reduce the environmental impacts of quarrying extractions. In recent years, the use of waste in the packaging of mortars and conglomerates has been increased and many companies offer the incorporation of waste glass as aggregate for concrete and mortars. There is still scientific debates on the opportunity to use glass related to the influence on workability and there are some concerns on the durability and resistance to degradation of products made with non-natural aggregates in conditions of interaction with alkali-rich waters.

In this work mineralogical-petrographical analyses have been carried out on sample and have shown that:

- use of glass influences compaction factors, therefore there is an increase in the air content also due to the involvement of numerous small particles. This produces high macroscopic and nanometric porosity, observed both on thin sections microscope observations and on SEM-EDSanalyses, which affects compressive, tensile and flexural strength of mortars and concrete in proportion to the content of waste glass used.

- microcracks in glass aggregates, produced by crushing, increase aggregate water interaction surface, so it tends to degrade more easily by hydrolysis, moreover the greater permeability to air and water accelerates carbonation processes.

- smooth surface of the waste glass decreases the adhesion force between glass surface cement.

- addition of waste glass to natural aggregates produces an improvement in workability due to the non-absorbent nature of the glass.

- In the short time inclusion of glass aggregates effectively improves the surface resistivity and the attack on sulphate but in the long time a secondary porosity for hydrolysis intervenes and the resistance decreased, and the carbonation rate increases.

- contraction from drying of the concrete decreases with the content of glass aggregates increasing, but subsequently the swellings by hydrolysis can produce a secondary porosity giving an intimate and widespread fracturing of the matrix

Petrographical both on thin sections and on crushed samples observation and SEM-EDS microanalysis have shown that degradation is due to the use of crushed natural aggregate mixed with recycling aggregate rich in common glass. This degradation has provided that alkaline elements interact with cement and with siliceous aggregates of the screed. It has been also noted that degradation is accelerated by the widespread presence of sulphur, sometimes in high concentrations and due to the use of recycled material, and the presence of iron. Degradation differences depend on a heterogeneous distribution of the C&D waste aggregate, so in the areas where it is less abundant, the phenomenon is less striking.

How to cite: Marrocchino, E., Eftekhari, N., and Vaccaro, C.: Degradation of concrete with glass enriched recycled aggregate used to flooring an industrial warehouse in Italy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13887, https://doi.org/10.5194/egusphere-egu2020-13887, 2020.

One of the most popular and intensively extracted building stones in Japan is a Miocene dacite-rhyolite ignimbrite known as Oya-ishi, quarried nearby the city of Utsunomiya (Tochigi). Traces of its historical usage in the last 1,500 years survive in vernacular architecture, construction, rock-cut and relief sculpture, but large-scale exploitation commenced only in the Edo period (i.e., from the 17^th century), an epoch of economic growth and flourishing arts and culture. Among the over 200 underground quarries in the region, few are still active, the others abandoned or converted into geoheritage and tourist attractions (e.g., History Museum, Heiwa Kannon monument, Keikan Park). Salt weathering is one of the decay aspects of Oya stone jeopardizing the preservation of those sites of historical and geological interest and, indirectly, visitor safety. The efflorescences on the tuff quarry walls turn out to be composed of sulfates, namely gypsum, mirabilite, and thenardite, their crystallization being controlled by the relevant microenvironmental conditions. In the extremely humid underground spaces, the phases having a very high deliquescence relative humidity are stable: gypsum is essentially ubiquitous, even in the deepest quarry levels, the most environmentally isolated; mirabilite needs a slightly dryer environment, so is observable in the middle levels or semi-underground quarries; thenardite requires further dryer conditions, and is mainly detected in the open air. The mechanisms of formation of these efflorescences are still under investigation: the classic minero-petrographic and geochemical characterization of the rock and its weathering phases is being supported by a microclimatic monitoring in different sites and seasons, and the chemical analysis of rainwater and groundwater. The research direction is aimed at the identification of the environmental and lithological constraints on the salt weathering of Oya tuff, that is: the spatial and temporal variability of relative humidity, and its influence on the cycles of salt crystallization/dissolution and the resulting mechanical stresses; the chemical driving forces, related to the rock mineralogy (zeolites, feldspar alteration, etc.) and water quality.

How to cite: Germinario, L. and Oguchi, C. T.: Salt weathering and geoheritage - Sulfate efflorescences in historical underground quarries of tuff, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-410, https://doi.org/10.5194/egusphere-egu2020-410, 2020.

The 3D models creating by SfM (Structure-from-Motion) photogrammetry became one of the important and convenient methods for any kinds of objects on geomorphology, geoheritage, or geoarchaeological fields. These objects are landforms, monuments, buildings, relics and so on. In order to evaluate these objects, it is necessary to collect morphological characteristics, and then proceeding to decide investigating points or areas of these materials.

The progress of this methods developed significantly, however, there have been still remained difficulties depending on the objects. For example, it is difficult to create 3D models that the object is too flat, too dark, and/or any restricts of combination of target size and focusing distances. The present study attempts to these difficulties by targeting to narrow and dark underground space. The investigating object is an archaeological man-made cave, called Taya Cave, in central Japan. It was excavated in 13 century originally and used as study areas for Buddhists by making Buddhism bas-reliefs. The cave has a total length of 570 m underground passage with a three-layer structure. The cave also has several domes connected by narrow paths. The present study tried to make a 3D model of this complicated, dark and narrow cave by SfM photogrammetry. In order to concur to make 3D models for the whole area of the cave, it is useful making chunks; separating several areas of simple morphology and then compiled. When facing narrow path, it is better to take photographs not by perpendicularly but by inclinedly. Furthermore, it is important to use strong light with attach to camera. After obtained the image data of the whole cave, the accuracy of the created model was evaluated. The results were that the accuracy of horizontal distances are higher than that of vertical distances.

How to cite: Oguchi, C., Shimizu, K., Tamura, Y., Hayakawa, Y., and Ogura, T.: An attempt of SfM photogrammetry to narrow and dark underground building heritage, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9774, https://doi.org/10.5194/egusphere-egu2020-9774, 2020.

In Morocco, no measures have been taken to manage residual waste from operational or abandoned mining and quarries sites.

Indeed, significant quantities of mine waste, composed of concentrator residues and sterile waste, have been abandoned after the closure of operations without any effective management or rehabilitation planning.

These residues could have harmful impacts on the environment: soil and water pollution, destruction or disturbance of natural habitats, visual impact on the countryside...

The valorization and sustainable management of mining waste appear to be adequate solutions to major environmental problems. The construction sector can be a profitable sector to absorb chemically stable mining waste.

The objective of this research work is to study the feasibility of recycling waste from the abandoned Kettara mine (Morocco) and gypsum waste rock in Sidi Tijji (Morocco) as raw materials in construction materials.

The study consists first of a geological characterization and then a characterization of the physical, chemical and mineralogical properties of the residues, followed by an evaluation of the mechanical properties of the composite mixtures based on the chemically stable residues.

The Kettara mine is located in the Jbilet Central Mountains, 30 km northwest of Marrakech. Geologically, the pyrrhotite district of Kettara corresponds to the outcrop area of the volcano-sedimentary series of Saghlef shales. For the gypsum quarry at Sidi Tijji, which is part of the Safi basin, characterized by Jurassic outcrops essentially formed by gypsum and carbonate formations.

Mineralogical and chemical analysis have shown that these waste products are still rich in minerals such as the waste from the Kettara mine; the FeO3 concentrated amounts to 55.6%. In addition, gypsum waste rock represents a concentration of 28.9% CaO. Therefore, a low water content for the majority of samples.

Adapting to the principles of integrated recovery and management of mining and quarry waste requires a cultural change within the industry, but also in the ministries concerned.

Keywords: Valorization, mine waste, mines and quarries, construction materials.

How to cite: Bouiji, A., witam, O., and Ibnoussina, M.: Characterization and valorization of the waste from the abandoned Kettara mine and the gypsum quarry in Sidi Tijji (Marrakech-Safi Region, Morocco)., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-887, https://doi.org/10.5194/egusphere-egu2020-887, 2020.

A multi-technique high resolution 3D modelling is described here aimed at the investigation of the state of conservation of carbonate columns of the 1000 BC ancient church of Buon Camino located in the homonymous district of the town of Cagliari (Italy).

The integrated application of different Non-Destructive Testing (NDT) diagnostic methods is of paramount importance to locate damaged parts of the building material of artefacts of historical buildings and to plan their restoration.

In this study a multi-step procedure was applied starting with a high resolution 3D modelling performed with the aid of Structure from Motion (SfM) Photogrammetry and Terrestrial Laser Scanner (TLS) methodologies. For this delicate task we operated simultaneously a Nikon D-5300 digital Reflex 24.2 Mega pixel Camera and a Leica HDS-6200 Terrestrial Laser Scanner. Subsequently, starting from the information detected with the above methods deeper material diagnostics was performed by means of high resolution 3D ultrasonic tomography aimed at the capillary definition of the elastic properties in the inner parts of the building materials. Measurements of longitudinal wave velocity from ultrasonic data were performed using the transmission method, namely two piezoelectric transducers coupled on the opposite sides of the investigated columns. The ultrasonic data acquisition was planned designing an optimal survey and providing a very good spatial coverage of the investigated columns. The columns were then criss-crossed by a large number of ray paths forming a dense 3D net. The SIRT (Simultaneous Iterative Reconstruction Tomography) algorithm was used to produce the 3D rendering of the velocity distribution inside the investigated columns. With this method the damaged parts were located and it was possible to distinguish them from the unaltered areas. The information on the superficial material conditions obtained by SfM and TLS techniques were compared and integrated with the information of the inner materials obtained by 3D ultrasonic tomography.

The results of the above non invasive geophysical techniques have been interpreted in the light of the different textural and petrophysical features of the study carbonate building materials. The study of the main textural features, such as the relationship between bioclasts, carbonate matrix, or that of the cement and petrophysical characteristics such as the nature and distribution of porosity were found to be of fundamental importance in the interpretation of the geophysical data (e.g. TLS reflectance and longitudinal acoustic wave propagation). Therefore a detailed analysis of the textures and pore microstructure were carried out from petrographic thin-sections in Optical and Scanning Electron Microscopy (OM/SEM). The final result of our multi-step-technique integrated methodology is a sophisticated 3D model with a high resolution 3D image representing the internal and external parts of the investigated columns in order to account for their static load resistance and possibly plan their conservation and restoration. The described procedure can also be applied to other cases in which a diagnosis is needed of the state of conservation of the variously shaped, layered-stones and composed artefacts typical of ancient historical buildings.

Key words: 3D Modelling, 3D Ultrasonic Tomography, Terrestrial Laser Scanner, SfM Photogrammetry, Non-Destructive Testing, Diagnostic, Ancient Columns, Stones

How to cite: Casula, G., Fais, S., Cuccuru, F., Bianchi, M. G., and Ligas, P.: High Resolution 3D modelling of Cylinder shape bodies applied to 1000 ancient BC columns, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1231, https://doi.org/10.5194/egusphere-egu2020-1231, 2020.

Decision on suitability of rocks for production of crushed stone and their use in specific constructional activities relies on series of empirically-designed tests which partly simulate certain degradation forces acting during the service of aggregates. Tests for integrity of crushed stone particles subjected to mechanical forces employ several approaches simulating abrasion, attrition, and/or crushing; these can thus be generally designated as technological-mechanical performance (TMP) tests. Design of these tests has nothing to do with testing of mechanical properties viewed as fundamental physical property. However, numerous authors attempted to correlate certain mechanical properties (specifically uniaxial compressive strength data) with TMP of crushed stone source rocks. Unfortunately, relatively low correlation has been generally achieved.

In the recent study, this approach is re-examined by using not only ultimate strength data, but also knowledge on deformational process and on its energetic parameters. The results of laboratory experiments show, that some of the obtained data exhibit much tighter correlation; however, one has be very careful in selection of proper parameters. Thorough understanding of damage mechanisms of crushed stone particles (i.e. mechanisms of their wear and breakage during service life) makes critical part of this evaluation process.

How to cite: Prikryl, R.: Relationship of mechanical properties of crushed stone source rocks to their technological-mechanical performance, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7835, https://doi.org/10.5194/egusphere-egu2020-7835, 2020.

Degree of size reduction of selected crushed-stone source rocks and its relationship to technological-mechanical performance parameters

Kateřina Krutilová (1), Richard Přikryl (2)

(1) Stone testing laboratory Ltd., Hořice v Podkrkonoší, Czech Republic

(2) Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43, Prague 2, Czech Republic

Particle size reduction (PSR) is one of the principal processing methods employed in extractive industry including production of crushed stone aggregates. The purpose of particle size reduction is production of certain size fractions which are directly applicable for final uses or necessary for further industrial activities. On industrial scale, crushing of rocks for crushed stone production is commonly performed in 2-3 successive steps (stages). The conditions of crushing in these individual steps is selected in order to reach lower reduction ratio, thus facilitating production of particles with favourable geometry. Conditions of crushing are influenced by numerous factors, of which only part was thoroughly investigated. In the recent study, we attempt to correlate knowledge on PSR behaviour of various petrographic types with other technological-mechanical performance parameters (e.g. Los Angeles attrition value, Nordic abrasion test, aggregate crushing value) and/or physical / mechanical properties of aggregate source rocks (specifically volcanic rocks of variable composition, ages, and properties). PSR behaviour obtained by experimental laboratory crushing (one-step process) is reported as degree of size reduction and reduction ratio. 

How to cite: Krutilová, K. and Přikryl, R.: Degree of size reduction of selected crushed-stone source rocks and its relationship to technological-mechanical performance parameters , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13464, https://doi.org/10.5194/egusphere-egu2020-13464, 2020.

Feldspar-rich leucogranite formed by metasomatic / hydrothermal alteration of original granite makes one of the key resources of feldspar raw material for ceramic / glass industries in the Czech Republic. Studied material is composed by prevailing albite and quartz accompanied with small amounts of minor / accessory phases which represent the major harmful components responsible for colour changes in final product. To improve quality of marketed feldspar, part of exploited raw material started to be processed by using magnetic separation in recent years.

To increase efficiency of processing, trials on usage of additional processing / separation methods have been applied in recent study. The approach involves three successive steps: (1) laboratory, (2) small-scale, and (3) full-scale separation schemes.

Concerning laboratory separation, several grams of input material were processed by using magnetic separation and gravity separation. This helped in separation of major harmful components (Fe-, Mn-, Ti-rich phases partly with complex mineralogical binding with Nb–Ta, Li-micas, and apatite).

Small-scale separation as a second step attempted to find optimized processing flow-chart usable for separation of some potentially interesting phases (Li-rich and Nb-Ta minerals). Control of the best granulometry presented one of the challenges. By studying various separation techniques, combination of dry magnetic separation and air gravity concentrating table proved to be very effective.

During full-scale separation several tons of input material were processed by magnetic separation followed by air-gravity concentrating table. The chemical composition of separation end-products was tested by XRF. Properties important for ceramic / glass industry (specifically experimental burning and colorimetric measurements) were checked as well. Such an approach allowed for realistic evaluation of the beneficiation flow-chart prior to its implementation on the industrial scale of processing of feldspar raw material.

How to cite: Vrbický, T. and Přikryl, R.: Processing waste from feldspar raw material as a potential source of certain strategic elements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9326, https://doi.org/10.5194/egusphere-egu2020-9326, 2020.

Heritage buildings are susceptible to environmental impacts, and many of the stone structures show intense damage due to weathering, soil instability or improper use. The detection of changes has primary importance in the understanding of deterioration processes, and it provides essential information for the preservation of these structures. The application of destructive techniques to assess the condition of the materials of these heritage structures are not feasible and in most cases, not permitted. Consequently, monitoring of the health of the construction material and the structure require techniques that are not destructive and automatically collects data from the sites. The study provides an overview of sensors that could be applied in monitoring of the conditions of cultural heritage structures. From the methods of placing sensors at sites to available data collection system – the entire process will be overviewed. Applications of spectroscopic sensors for in situ and real-time analysis of critical colorimetric parameters of building materials will be presented. Application of artificial intelligence-based data processing in the prediction of material degradation is also discussed. Optical detectors of remote sensing techniques applied in monitoring of heritage buildings are also addressed. The financial support of National Research, Development and Innovation (NKFI) Fund (K 116532) is appreciated.

How to cite: Török, Á. and Antal, Á.: Sensors applied in the detection of physical changes at heritage buildings, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19023, https://doi.org/10.5194/egusphere-egu2020-19023, 2020.

One of the most important weathering processes on stone-built monuments is the crystallization of salts. Since the transport material of these substances is water, the porous rock types are particularly affected. In Hungary many monuments and historic buildings have been constructed from oolithic Miocene limestone. So in this study, the effect of salt crystallization on the physical and mechanical properties of high porous limestone has been investigated. Samples were obtained from Sóskút (near to Budapest, the capital city of Hungary).

At first the petrophysical properties of the stone were determined. The porosity of the investigated stone type was 26-34 V/V%, the uniaxial compressive strength (4-5 MPa) and the Brazilian tensile strength (0,4-0,5 MPa) were very low. A special proper of this rock type is the large-pore system (2-3mm) between the ooid fragments.

Sodium chloride (NaCl) and sodium sulphate (Na₂SO₄) were used to investigate the effect of salt crystallization. Cylindrical rock samples were exposed to salt solutions of 14 m/m% Na₂SO₄ (MSZ EN 12370) and 5% NaCl solution (sea water salt content). After 15 salted water saturation- drying cycles the changes of mineralogical and petrophysical properties and indirect tensile strength of the samples were investigated. The damages on the pore walls were determined with scanning electron microscope (SEM) and the building of scaling layers on the stone surfaces were investigated with optical microscope.

How to cite: Rozgonyi-Boissinot, N. and Khodabandeh, M. A.: Damaging effect of salt crystallization on highly porous limestone from Hungary, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18766, https://doi.org/10.5194/egusphere-egu2020-18766, 2020.

The Eufrasius Cathedral of Poreč in Istria Peninsula, Croatia, was built in the 6th century, The nave collapsed in parts due to the AD 1440 earthquake. Nave and aisles are supported by 18 monolithic columns of Proconnesian marble. Seventeen of the columns bear various fractures, forming two groups: (1) axis-parallel fractures and (2) oblique fractures. Azimuths of dip directions of oblique fractures indicate N-S shaking.

In this study, the fracture development and cracking of a stone column was modelled using computer code. To model the current fracture pattern and to link it to seismic activity a Lagrangian analysis of continua in three dimensions (FLAC3D) is employed to reveal the non-linear behaviour of the stone column. A 3-Dimensional model based on discrete-element-method (DEM) has been created to study the failure process of the ancient stone column under static and dynamic loads. A combination of vertical and horizontal loads with a dynamic load due to the earthquake has been imposed horizontally. The influence of different parameters such as mechanical properties of rock, the magnitude of the earthquake were also assessed to observe their influence on the failure mechanism of rock. The DEM model was able to describe the observed crack pattern and it has proved the applicability of FLAC3D to describe failure mechanism of stone columns.

How to cite: Besharatinezhad, A., Török, Á., Al-Tawalbeh, M., and Kázmér, M.: Modelling of seismicity-induced cracking of stone columns using discrete-element-method (DEM), a case study of Eufrasius cathedral, Porec, Croatia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10462, https://doi.org/10.5194/egusphere-egu2020-10462, 2020.

The presented investigations are focused on a part of the 13^th century Church of the Holy Trinity Dominicans monastery in Cracow, Poland, and include the wall façade of the 17^th century Myszkowski chapel. The chapel was probably designed by Santi Gucci Fiorentino and built by his workshop. Southern façade of the chapel is made of Tertiary limestone blocks that make characteristic rusticated wall. Lower part of the façade is covered with cement and the basement is made of irregular fragments of Jurassic limestone and Cretaceous sandstone partly replaced and bound with cement mortar. The façade revealed clear signs of damage ranging from dark gray soiling of the surface, scaling to efflorescences. The last ones – mainly on the border of limestone blocks and the cement in the part of the basement.

Laboratory tests included mineralogical, chemical and petrophysical analyses. Optical microscopy, scanning electron microscopy (SEM-EDS), micro-Raman spectroscopy and X-ray diffractometry (XRD) were used for analysing materials and deterioration products of the cement render and mortar. The petrophysical properties of the materials have been performed using mercury intrusion porosimetry. The secondary minerals detected include mainly gypsum CaSO₄·2H₂O, thenardite Na₂SO₄,  aphthitalite (Na,K)₃Na(SO₄)₂, darapskite, Na₃(SO₄)(NO₃)·H₂O, nitre KNO₃, nitratine NaNO₃, ettringite Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O and monosulphite Ca₄Al₂O₆SO₃·11H₂O. Lower blocks of the façade covered with cement contain chiefly gypsum, ettringite and monosulphite, cement from the basement – gypsum and nitre; while efflorescences – thenardite, aphthitalite, darapskite, nitre and nitratine. The origin of the salts have been discussed and the differences in their type have been associated with composition of the materials and their physicochemical properties.

This work has been financially supported by the AGH University of Science and Technology, statutory grant no. 16.16.140.315.

How to cite: Marszałek, M., Dudek, K., Gaweł, A., and Czerny, J.: Cement render and mortar and their damages due to salt crystallization in the Holy Trinity Dominicans monastery in Cracow, Poland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18280, https://doi.org/10.5194/egusphere-egu2020-18280, 2020.

For a long time, historical mortars were primarily associated with mortars based on calcium carbonate as the main binder phase. Recent publications show that considerable amounts of magnesium are often present in the binder of historical mortars, which is referred to the use of dolomite rock as raw material (Diekamp, ​​2009; Diekamp, ​​2014). A special feature are Roman and medieval dolomitic lime mortars with the addition of brick fragments as a pozzolanic component (Schidlowski, 2019).In order to characterize the phase formation in modern pozzolanic dolomitic lime mortars, mortar prisms based on dolomitic lime were produced with three different pozzolans (antique and modern brick dust and metakaolin). To draw comparisons with other binders, identical prisms based on calcite and magnesite were produced. These specimens were stored under different environmental conditions (60 % and 95 % relative humidity) and examined by X-ray diffraction and simultaneous thermal analysis after periods of 28, 90 and 180 days.

The results obtained so far show that the binder phases that have evolved in the mortars based on dolomitic lime are calcite, aragonite, portlandite, brucite and AFm phases. Aragonite is only found in traces in the samples with metakaolin. In contrast to the samples stored at 65 % relative humidity, the samples stored at 95 % relative humidity have lower calcite and higher contents of portlandite and AFm phases.

No significant differences in the amount of calcite and water-containing mineral phases (portlandite, brucite, hydrotalcite) can be found after 28, 90 and 180 days. It can be concluded that a large part of the reactions has already taken place after 28 days.

The present study is believed to be beneficial for a thorough understanding of the phase formations in dolomitic lime based mortars at different curing conditions.

How to cite: Schidlowski, M., Bader, T., and Diekamp, A.: Mineralogical investigations on pozzolanic dolomitic lime mortars to assess the phase development at different curing conditions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20057, https://doi.org/10.5194/egusphere-egu2020-20057, 2020.

The design of restorative mortars for historical buildings and artefacts is always a challenging task, with multiple requirements which have to be achieved and harmonized. Essentially, restorative mortars have to comply with chemical, mineralogical and mechanical compatibility criteria, which also include formation of contact zone, tensile strength, porosity and visual properties (colorimetric parameters). One of the successfully restored examples is the mosaic discovered broken in 2014 with severely disturbed positioning of fragments. The mosaic represents head of Medusa dated from Late Roman period and found at the archaeological site in Skelani, Bosnia and Herzegovina.

The case study presented in this abstract is a good practice example of collaboration between restoration and science which shortens the period for attaining relevant inputs and gives confidence to future restoration decisions. The investigation reviled that the mosaic bedding layer was of very good quality and has allowed fragments of various sizes to be preserved (tesselatum, nucleus and even rudus layer on some fragments). The objective of the restoration was to preserve remains of the original bedding layer and to connect and stabilize groups of individual fragments. The idea was to design compatible restoration mortar which will support the requirements for future mosaic presentation.

The characterization of historic inorganic binder samples, performed in the Laboratory for Materials in Cultural Heritage, Faculty of Technology, University of Novi Sad, provided invaluable information about the composition of mosaic bedding layers, their preparation, and moreover about degradation mechanisms in regard to centuries of its use and environmental conditions. It was reviled that the original inorganic binder is a lime based mortar with brick fragments imbedded. A strong bonding with preserved bedding layers of mosaic fragments and a set of specific compatibility objectives framed attempts to design compatible restorative mortar. In the laboratory a set of restorative mortar samples were prepared with similar chemical and mineralogical composition, porosity and visual properties (colorimetric parameters), mechanical properties and formation of contact zone between original and restorative mortar. The laboratory prepared samples were artificially aged in weathering chamber (temperature, humidity, UV/VIS radiation) simulating exposal to real environmental conditions in all four seasons. The weathering regimes were set according to temperature and humidity profiles for the relevant region. Finally, the compatibility of restoration mortar with original one was evaluated and confirmed, what enabled conservators to proceed with restorative works.

How to cite: Ranogajec, J., Vucetic, S., Frankovic, M., and Hirsenberger, H.: Characterization of historical inorganic binders and design of restorative materials - case study of the late Roman mosaic, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18128, https://doi.org/10.5194/egusphere-egu2020-18128, 2020.

In Tyrol, Austria, dolomite rock was commonly used as raw material for historic mortars and plasters. During calcination of dolomite rock, almost equal amounts of calcium oxide and magnesium oxide are produced. While the reactivity of calcium oxide is well known, the reactivity of magnesium oxide is still not completely understood. Within this study, the reactivity of magnesium oxide obtained from calcination at different temperatures (600 - 1000 °C) will be examined. For this purpose, natural magnesite (Hochfilzen, Tyrol) will be used instead of natural dolomite rock in order to minimise the influence of calcium oxide on the wet slaking curves. Both, calcination and slaking of magnesite will be studied with the help of X-ray diffraction analysis and thermogravimetric analysis. The gained knowledge is believed to be beneficial for improving the understanding of degradation processes. The study was performed within the Interreg V-A Italy-Austria project named DOLOMIA (ITAT 2036) with the funding by INTERact and the European Regional Development Fund (ERDF) being grateful acknowledged.

How to cite: Bader, T. and Diekamp, A.: Assessing the reactivity of magnesium oxide calcinated at different temperatures for understanding its role in degradation processes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19671, https://doi.org/10.5194/egusphere-egu2020-19671, 2020.

Natural Stone has always been one of the most widely used and appreciated materials in the construction of important structures, buildings and works of art. It is extremely important that the stone purchased by the consumer meets the expectations for which it was chosen, being colour one of the main aspects. Currently, there are companies with very high costs in the replacement of altered stone.

This work arises from the companies’ need to seek the extraction of stone blocks that ensure a lower susceptibility to colour change after application. To do so, a geochemical/mineralogical study was applied in a quarry located in the northern region of Lisbon, where one of the most important Portuguese lithotypes is currently explored. Featured by its excellent physico-chemical characteristics, this lithotype is further characterised by the coexistence of a blue and cream colour. The work aimed to study the presence of a mineral, pyrite, responsible for the natural discolouration of this construction resource.

The results obtained show a greater predominance of pyrite in the darker fractions of the rock, which increases while the exploration level is deeper.

How to cite: Dias, L., Silva, R., Lopes, L., Candeias, A., and Mirão, J.: Guessing stone behaviour before extraction, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7843, https://doi.org/10.5194/egusphere-egu2020-7843, 2020.

Recent challenges faced by humanity in relation to the ongoing climatic changes around the globe, have led many practitioners and researchers search for new environmentally friendly materials to use in construction, such as earth-based materials. A specific form of an earth-based building material that nowadays receives particular attention is Compressed Earth Blocks (CEBs). CEBs comprise of soil mixed at low moisture content and are formed under high pressure in compression, without firing. The end-products can be non-stabilized, i.e., without any cement or lime added, or stabilized, whereby a small quantity of stabilizer (<12% by weight) is added, mainly for enhancing their mechanical and durability properties. CEBs, particularly the non-stabilized ones, are considered to be less expensive and environmentally friendlier, compared to the traditional fired clay bricks, due to their lower production cost and excellent recyclability potential, which significantly reduces the end-product’s environmental impact.

In Cyprus, CEBs were not used in the past, as the prevailing earth building technique on the island was adobe masonry. Recently, however, there appears to be an interest in the use of this material for contemporary construction. The work hereby presented is part of an ongoing research project that focuses on the design, production and characterization of a sustainable and eco-friendly prototype CEB masonry system that will be fabricated using raw materials originating from Cyprus. The project is funded by the European Regional Development Fund and the Republic of Cyprus, through the Cyprus Research and Innovation Foundation (Project ENTERPRISES/0618/0007).

In the framework of the aforementioned project, various types of locally sourced soils, with different mineralogical/granular composition and plasticity characteristics have been selected and used for the production of non-stabilized CEBs. A series of tests, including particle-size analysis, Atterberg limits determination, shrinkage and compaction measurements, and X-ray diffraction analyses have been carried out to determine the characteristics of the raw materials selected. In addition, compression and 3-point bending tests, capillary absorption measurements and thermal conductivity analyses have been conducted to assess the physico-mechanical properties of the CEBs produced.

XRD analyses have shown that the soils investigated are mainly composed of carbonates and silicates at different ratios. Preliminary capillary absorption tests have demonstrated that the use of a non-reactive liquid, such as acetone, is better over water in determining the sorptivity of non-stabilized CEBs. In addition, the thermal conductivity of all specimens ranged between 0.60-0.85 W/mK. Finally, the results suggest that, despite the different granular composition of the soils used, all soils demonstrated adequate mechanical properties in terms of compressive (over 5 MPa) and flexural (over 0.5 MPa) strength.  

How to cite: Kyriakides, M., Panagiotou, R., Illampas, R., Tapakoudis, M., and Ioannou, I.: Physico-mechanical characterization of non-stabilized Compressed Earth Blocks , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9458, https://doi.org/10.5194/egusphere-egu2020-9458, 2020.

In this contribution we present the first results for proposing an analytical protocol to analyze fly ashes (FA) with XRF.

Fly ashes resulting from the incineration of municipal solid waste (MSW) should be considered as a hazardous material, mainly due to its potential high heavy metal content. Therefore, they have to be chemically fully characterized to facilitate primarily their safety storage and subsequently the recovery as second raw material resource. It’s worth noticing that fly ashes bulk chemistry (including volatile contents) depends on many types of variables [i.e.: geography; air pollution control devices (APCDs) and sampling sites], all related to the nature of the waste. On the basis of available data from different European waste-incineration plants, the bulk major elements contents are: Al <0.1-4.6 wt%; Ca 23.7-38.9 wt%; Fe 0.20-2.17wt%; K 0.1-2.4 wt%; Mg 0.5-1.7 wt%; Mn 0.02-0.12 wt%;  Na <0.15-2.5 wt%; P <0.02-0.92wt%; Si 0.2-8.7 wt% Cl, 7.5-28.3wt%, with volatile contents (tested by Loss of Ignition) in the range of 15-40 wt% (De Boom e Degrez, 2012; Bodénan and Deniard, 2003). 

If we consider fly ashes as “rock type” material, x-ray fluorescence (XRF) is used effectively for determining the major rock-forming elements.  However, the lack of standard calibration for this material suggested us to adopt a different strategy of calibration, using the method of Standard Addition (SA) to determine SiO₂ and Al₂O₃ having similar mass absorption coefficients (https://physics.nist.gov/PhysRefData/XrayMassCoef/tab3.html).  

The SA method was originally designed to determine trace elements contents by addition of comparative amounts of analytes. In order to keep the characteristics of bulk chemistry invariant, in this modified calibration procedure we prepared eleven pressed powders by adding several known aliquots of SiO₂ and Al₂O₃ (“excipients”) to the same amount of unknown FA in the constant proportion of 10% and 90%, respectively.

Plotting together the intensity values of the two analytes with the various percentages by weight of “excipients”, it was possible to generate calibration lines and acquired the percentage by weight of the two analytes in the unknown material. The Si and Al contents obtained by the calibration lines are 1.93 wt% and 1.64 wt%, respectively.

These values are different from those (2.86 wt% and 1.40 wt% for Si and Al, respectively), obtained by measurements of pure FA with routine XRF standard calibrations for silicatic rocks (Franzini et al. 1975). More measurements are needed to evaluate the accuracy of the method, however, the results presented here are promising, and hint that XRF may be used efficiently to measure FA major element chemistry, by applying the modified standard addition calibration.

References:

Bodénan, F. and Deniard P. (2003). Chemosphere, 51; 335-347

De Boom A. and Degrez  M. (2012). Waste Management, 32; 1163-1170

Franzini M., Leoni L. and Saitta M. (1975). Rend. S.I.M.P., 31: 365-378.

How to cite: Tassinari, R., Guida, R., Caviglia, C., Destefanis, E., Bonadiman, C., Brombin, V., Bernasconi, D., and Pavese, A.: Fly ashes bulk chemistry: a new approach for XRF measurements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17865, https://doi.org/10.5194/egusphere-egu2020-17865, 2020.

In Canton Ticino, Switzerland, the exploitation of natural stone, mostly gneisses, is an important activity of valley’s economies but in the last decades the local quarries are facing severe economic difficulties. The current rules on the disposal of quarry wastes and the territorial planning that regulates the structure of quarries and inert landfills, is putting pressure on the economy and profitability of quarries, as the wastes represent up to 40% of the extracted material and disposal costs are huge given the important volumes. Therefore, the sustainable development of the quarry sector needs new and effective strategies, in particular in the management of quarry waste to reduce its disposal costs and possibly to re-enhance this material. Here, we propose an example of an environmentally friendly circular economy based on crushed aggregates of quarry waste for the building of high added value constructional elements.

In this applied study, we characterized the waste materials (different types of gneisses) and evaluated the crushed aggregates for their use in traditional concretes and in innovative geopolymers to use in 3D printing systems. The results showed that the concretes produced with 100% quarry waste (crushed aggregate) have good mechanical properties but moderate durability. However, it has been observed that even by simply mixing these crushed aggregates with a part of fluvial sand (allochthonous) it is possible to improve the performance of the concrete in all respects. Hence, this environmentally friendly material is suitable for many applications in the concrete industry. The aggregates were also tested for powder bed 3D printing that uses geopolymers as a binder. The first tests with this printed geopolymer suggest that this innovative constructional material may be used in non-structural architectural elements, however, further investigation is needed.

In this project it has been mapped, within the construction industry, how the economic supply chain could be configured for the reuse of this material. In particular, the usability in the production of concretes, geopolymers and mortars was highlighted, both in traditional applications and with innovative applications such as 3D printing. The analysis was carried out with particular attention to the concepts of circular economy and sustainability, identifying the main actors and their potential interests within the supply chain.

How to cite: Antonietti, S., Schenker, F. L., Blazquez, V., Voney, V., Odaglia, P., Zerbi, S., Coppola, L., Bernardi, C., Corboud, F., Ferrari, D., Ambrosi, C., and Pozzoni, M.: Quarry waste for the production of sustainable and innovative constructional materials , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18787, https://doi.org/10.5194/egusphere-egu2020-18787, 2020.

Cavitation erosion, widely existing in many flood discharge structures of concrete dams, has a direct impact on the performance of concrete. Understanding the cavitation erosion properties of concrete with different damage degrees is vital to the long-term operation safety of concrete dams. In this study, the cavitation erosion properties of concrete with different damage degrees under ultrasonic cavitation are systematically investigated in the laboratory, including three damage degrees and three ultrasonic cavitation intensities. Based on the stress-strain curve of concrete under uniaxial compression, the damage variable is defined and the corresponding concrete specimens are pre-treated. The experimental results reveal the influence of the damage degrees on the cavitation erosion properties of concrete, regarding the mass erosion characteristics, the predominant failure behaviour, and the coupling effect mechanism. Image analysis of the specimens shows some level of deterioration at the surface and inside the specimens. Under higher damage degree or cavitation intensity, the concrete is characterized by higher mass erosion rate, higher cumulative cavitation damage and worse surface smoothness. Furthermore, the micro-cracks caused by concrete damage aggravate the aggregate liberation of concrete under ultrasonic cavitation, and the crack propagation under coupling effect of damage and cavitation is most likely driven by the combination of fatigue-like crack growth and deformation, thereby reducing the service life of concrete.

How to cite: Lu, X., Chen, J., Pei, L., and Wu, Z.: Experimental Investigation on the cavitation erosion properties of concrete with different damage degrees under ultrasonic cavitation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1917, https://doi.org/10.5194/egusphere-egu2020-1917, 2020.