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Chemical and microstructural analysis of plaster sampled from the castle Sychrov (CR) – Breton tower
Slížková, Zuzana; Frankeová, Dita; Bauerová, Pavla; Náhunková, Pavla
2022 - Czech
The analysed mortar contains 76.5% by weight quartz sand and 23.5% wt. the lime binder - it is highly hydraulic lime. The aggregate of the mortar is made up mostly of quartz. The hydraulicity of the contained lime binder is evidenced by the presence of belitic clinkers, a strongly inhomogeneous microstructure (typical alternation of dense, Ca-enriched parts and more porous decalcified areas) and the presence of silicate components in varying degrees of reaction. It is suggested that the hydraulic binder used could have been artificially prepared by mixing lime with a hydraulic silicate additive. Analyzovaná malta obsahuje 76,5 % hm. křemičitého písku a 23,5 % hm. tvoří vápenné pojivo - jedná se o silně hydraulické vápno. Kamenivo malty je tvořeno v naprosté většině křemenem. Hydraulicitu obsaženého vápenného pojiva dokazuje jednak přítomnost belitických slínků, silně nehomogenní mikrostruktura (typické střídání hutných, Ca nabohacených částí a poréznějších dekalcifikovaných oblastí) a dále přítomnost silikátových složek v různé míře zreagování. Nabízí se domněnka, že použité hydraulické pojivo mohlo být připraveno uměle smícháním vápna s hydraulickou silikátovou přísadou.
Keywords:
historic mortar; lime mortar; chemical analysis; SEM-EDS; termal analysis
Available at various institutes of the ASCR
Chemical and microstructural analysis of plaster sampled from the castle Sychrov (CR) – Breton tower
The analysed mortar contains 76.5% by weight quartz sand and 23.5% wt. the lime binder - it is highly hydraulic lime. The aggregate of the mortar is made up mostly of quartz. The hydraulicity of the ...
Survey of the terrain and structures under the floor of The Mother of God Church (The Telč Old Town)
Válek, Jan; Kotková, Kristýna; Kozlovcev, Petr
2022 - Czech
A non-destructive survey of the building structures hidden under the current level of the Church of the Mother of God in the Old Town of Telč was carried out using ground-penetrating radar. The survey revealed the occurrence of hidden constructions that are related to the current concept of the church and its construction solution. Byl realizován nedestruktivní průzkum stavebních konstrukcí skrytých pod současnou úrovní kostela Matky Boží na Starém Městě v Telči pomocí zemního radaru. Průzkum odhalil výskyt skrytých konstrukcí, které mají vztah k současnému pojetí kostela a jeho stavebního řešení.
Keywords:
ground penetrating radar (GPR); cultural heritage; non-destructive testing
Available at various institutes of the ASCR
Survey of the terrain and structures under the floor of The Mother of God Church (The Telč Old Town)
A non-destructive survey of the building structures hidden under the current level of the Church of the Mother of God in the Old Town of Telč was carried out using ground-penetrating radar. The survey ...
Aerodynamic interference forces acting on two square prisms in a model atmospheric boundary layer
Macháček, Michael; Lo, Y. L.; Máca, J.
2022 - English
The presented experimental analysis focuses on the definition of interference factors for aerodynamic forces acting on two square prisms depending on their relative position. Both prisms used had the same dimensions and a height to width ratio of 6 - this ratio is relatively common in high-rise buildings. The experiment was performed in a wind tunnel with a model atmospheric boundary layer, which represented a dense urban area. The forces acting at the base of one of the buildings were measured, and by moving the other building it was possible to measure 204 mutual configurations, i.e., 204 interference positions. In all positions, the windward facades of the small-area model were placed perpendicular to the direction of the incoming flow. This created a detailed map of the interference effect on a wind-loaded pair of buildings. The results show a significant effect of the relative position of buildings on wind loads. A significant increase in\nload occurred due to the proximity of buildings. Due to the interference effect, wind load fluctuations can increase by up to 28% and average values by up to 36%.
Keywords:
interference effect; two square prisms; wind tunnel experiments; turbulent boundary layer
Available in digital repository of the ASCR
Aerodynamic interference forces acting on two square prisms in a model atmospheric boundary layer
The presented experimental analysis focuses on the definition of interference factors for aerodynamic forces acting on two square prisms depending on their relative position. Both prisms used had the ...
Tomographic investigation of the sandstone fracture toughness
Vavřík, Daniel; Beneš, Pavel; Fíla, Tomáš; Koudelka_ml., Petr; Kumpová, Ivana; Vavro, Martin
2022 - English
It is well known that the measured values of the fracture toughness of quasi brittle materials are influenced by material heterogeneity, dimensions, boundary conditions, and unequal tension and compression properties. Standard testing methods supposing isotropic material, in contrary the quasi-brittle materials differ from this theoretical expectation, therefore this approach may fail. The authors present Local Fracture Toughness Testing (LFTT) method to overcome this obstacle. LFFT based on a complex methodology using a series of tomographic reconstructions recorded during specimen loading is calculated independently of the outside boundary conditions.
Keywords:
fracture process zone; crack path; quasi-brittle material; X-Ray computed tomography; four-point bending test
Available in digital repository of the ASCR
Tomographic investigation of the sandstone fracture toughness
It is well known that the measured values of the fracture toughness of quasi brittle materials are influenced by material heterogeneity, dimensions, boundary conditions, and unequal tension and ...
Selection of mortars samples for radiocarbon dating
Válek, Jan; Kozlovcev, Petr; Fialová, Anna; Kotková, Kristýna; Frankeová, Dita; Skružná, Olga; Maříková-Kubková, Jana; Tomanová, Pavla; Herichová, Iva; Světlík, Ivo; Pachnerová Brabcová, Kateřina; Šimek, Pavel
2022 - Czech
Radiocarbon dating of organic residues may not always correctly determine the age of analysed historic mortars. Therefore, it seems advantageous to use of carbon dating of the carbon contained in the structure of the lime mortar, which will provide representative data of the age of the investigated structure. The methodology presents basic instructions and rules for sample selection, processing, and evaluation. The aim of this methodology is the identification of cases where the radiocarbon dating of a binder is appropriate and to define the reasons why some binder systems fail to provide relevant results. Radiokarbonové datování organických zbytků nemusí vždy správně vypovídat o stáří analyzované historické malty. Proto se zdá výhodné využití možnosti datace uhlíku obsaženého ve struktuře vápenné malty, který při správném zpracování poskytne reprezentativní údaje o době vzniku studované konstrukce. Metodika představuje základní návod pro výběr vzorků, jejich zpracování a vyhodnocení. Cílem metodiky je identifikace případů, kdy je radiouhlíková datace pojiva vhodná a vymezení důvodů proč se u některých pojivových systémů nedaří získat relevantní výsledky.
Keywords:
historic binders; mortars; radiocarbon
Available in a digital repository NRGL
Selection of mortars samples for radiocarbon dating
Radiocarbon dating of organic residues may not always correctly determine the age of analysed historic mortars. Therefore, it seems advantageous to use of carbon dating of the carbon contained in the ...
Preparation of mortars samples for radiocarbon dating by mechanical separation
Válek, Jan; Kotková, Kristýna; Fialová, Anna; Kozlovcev, Petr; Králová, Karolína; Světlík, Ivo; Pachnerová Brabcová, Kateřina
2022 - Czech
The methodology establishes the procedure for mechanical separation of the binder from the mortars to determine their age using the radiocarbon method. Along with the procedure, there is also a method of verifying the quality of purification using optical microscopy supplemented with cathode luminescence. The methodology is developed on the basis of the current state of knowledge and presents the basic sample preparation procedure in the form of a detailed description of the proven method of mechanical separation of the binder from lime mortar samples together with possible problems and an evaluation of the separation quality. Metodika stanovuje postup mechanické separace pojiva z malt pro stanovení jejich stáři radiouhlíkovou metodou. Spolu s postupem souvisí i způsob ověřování kvality přečištění pomocí optické mikroskopie doplněné o katodovou luminiscenci. Metodika je vypracovaná na základě současného stavu poznání a předkládá základní postup přípravy vzorků v podobě podrobného popisu ověřeného způsobu mechanické separace pojiva ze vzorků vápenných malt spolu s možnými problémy i hodnocením kvality separace.
Keywords:
mortars; lime binder; radiocarbon; AMS dating
Available in a digital repository NRGL
Preparation of mortars samples for radiocarbon dating by mechanical separation
The methodology establishes the procedure for mechanical separation of the binder from the mortars to determine their age using the radiocarbon method. Along with the procedure, there is also a method ...
Stone surface topography of Prague historic monuments over the centuries
Kovářová, K.; Cihla, Michal; Malát, R.; Semerád, M.; Tryml, M.
2022 - English
Stonemasons tool traces on stone surface are undoubtably a significant part of monument historic value. As any other profession, stonemasons craft develops over time and has its own specifics in every period. Each work has its own unique pattern and bears traces of individual stonemason workshops, tradition, etc. The study of building stone cutting is based on evolving methods of mechanoscopy and analytical traceology. Stone traceology deals with traces in material and the subsequent reconstruction of tools and the processes of stoneworking. The interpretation of data in terms of determining the actual trace is called a mechanoscopy. When studying a stone surface, the latest 3D modelling technology is used with subsequent analyses by means of Global Mapper software. The use of these methods enables reconstruction of the craftsman’s tools. The presented article is an extract of a study that systematically maps the stone cutting work in the territory of Prague from the oldest buildings to the present day. For example, stonework in 9th century Prague was gradually evolving from simple stone block modelling to sophisticated cutting of blocks in the 12th century. This information can be very useful in the process of monument care.
Keywords:
stone topography; Prague; craftmanship; stonemason tool; tool traces
Available at various institutes of the ASCR
Stone surface topography of Prague historic monuments over the centuries
Stonemasons tool traces on stone surface are undoubtably a significant part of monument historic value. As any other profession, stonemasons craft develops over time and has its own specifics in every ...
Creep of oak dowel: various loading and environmental conditions
Hasníková, Hana; Kunecký, Jiří; Hataj, M.
2022 - English
For research of timber joints, the crucial role in force distribution inside the joint is played by distribution and variability of stiffness of the dowels. Not only the instant stiffness, but the one that we can encounter after some longer period. Also, this value and its statistical distribution is influenced by many other factors, however, humidity and temperature are in timber (oak) dowels of utmost importance. In the work results of a creep experiment made using a special testing rig is presented. It has been found, that biggest changes in creep behavior are in case if very humid conditions are present, and, also, that cycling the temperature in high humidity conditions can produce about 104% of the original instantaneous displacement. The result is not surprising, however, new insights are made thanks to relatively high number of samples and ability to produce some statistics. Another outcome is relation of dowel stiffness in time to the level of applied stress, which is quantified in the article.
Keywords:
oak dowel; creep; humidity
Available at various institutes of the ASCR
Creep of oak dowel: various loading and environmental conditions
For research of timber joints, the crucial role in force distribution inside the joint is played by distribution and variability of stiffness of the dowels. Not only the instant stiffness, but the one ...
Chemical and microstructural analysis of plaster samples from the Mayrau mine, Kladno – Vinařice
Slížková, Zuzana; Frankeová, Dita; Vondráčková, Michaela; Bauerová, Pavla; Náhunková, Pavla
2022 - Czech
An analysis of historical plasters was carried out using thermal analysis and SEM-EDS analysis. The binders and aggregates of mortars and their surface treatments were characterized. The survey results were used for the design of the repair mortars. V rámci stavebně-technického průzkumu byl proveden rozbor vzorků historických omítek s využitím termické analýzy a SEM‐EDS analýzy. Byla provedena charakterizace plniva a složek pojiva malt a jejich povrchových úprav. Výsledky průzkumných prací byly použity jako podklad pro návrh rekonstrukce objektu.
Keywords:
TGA; SEM/EDS; binder characterization
Available at various institutes of the ASCR
Chemical and microstructural analysis of plaster samples from the Mayrau mine, Kladno – Vinařice
An analysis of historical plasters was carried out using thermal analysis and SEM-EDS analysis. The binders and aggregates of mortars and their surface treatments were characterized. The survey ...
Proceedings of the SHATIS 2022 – 6th International conference on structural health assessment of timber structures
Kunecký, Jiří; Hasníková, Hana
2022 - English
Structural health assessment of timber structures associates various procedures in order to evaluate the safety and serviceability of structures. Also, it helps to assure or extend the predicted service life of structures. Service life sustainability can be promoted by the incorporation of monitoring systems or by providing tools and methods that deliver accurate reports about the structural condition. Conservation and assessment of timber structures is based on a multidisciplinary approach. The conference topics cover the wide spectrum, from wood properties, through performance of joints and timber design, to modern monitoring and digital technologies. As the topics include both existing and historical timber structures, the need for reliable non destructive testing methods is part of the approach as well.
Keywords:
timber structures; monitoring and survey; design
Available at various institutes of the ASCR
Proceedings of the SHATIS 2022 – 6th International conference on structural health assessment of timber structures
Structural health assessment of timber structures associates various procedures in order to evaluate the safety and serviceability of structures. Also, it helps to assure or extend the predicted ...
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