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Criteria for selecting, preparation and processing of a replacement stone for ashlar masonry restoration – sedimentary rocks
Bláha, Jiří; Kovářová, K.; Buzek, Jaroslav; Panáček, M.; Cihla, M.; Rafl, T.; Hejný, L.; Rybařík, V.; Chamra, S.; Schröfel, J.
2016 - Czech
Geologists, structural engineers, construction historians, conservationists and restorers formulated their views on the relevant intensity of interventions, the replacement stone quality and also the parameters of processing by craftsmen. Methodical guidelines define the necessary level of adequate historical, technological and structural surveys and, subsequently, propose an optimal procedure for laboratory tests and for the following repair processes of a particular structure. Geologové, stavební inženýři, stavební historici, památkáři a restaurátoři v metodice shrnuli své požadavky na přiměřenou intenzitu zásahů, kvalitu náhradního kamene a parametry řemeslného opracování. Metodika současně stanovuje nezbytnou úroveň historických, technických a technologických průzkumů a navrhuje optimální skladbu laboratorních zkoušek souvisejících s přípravou opravy konkrétní stavby.
Keywords:
conservation and restoration; sedimentary rocks; ashlar masonry; stone dressing
Available in a digital repository NRGL
Criteria for selecting, preparation and processing of a replacement stone for ashlar masonry restoration – sedimentary rocks
Geologists, structural engineers, construction historians, conservationists and restorers formulated their views on the relevant intensity of interventions, the replacement stone quality and also the ...
Influence of ice accretion at bridge rope on Strouhal number
Pospíšil, Stanislav; Gorski, P.; Kuznetsov, Sergeii
2015 - English
The paper is concerned with the method and results of wind tunnel investigations of the/nStrouhal number (St) of a stationary iced cable model of cable-supported bridges with/nrespect to different angles of wind attack. The methodology leading to the experimental/nicing of the inclined cable model was prepared in a climatic section of the laboratory./nThe St values were determined within the range of the Reynolds number (Re) between/n2.4·104 and 16.5·104, based on the dominant vortex shedding frequencies measured in/nthe wake of the model.
Keywords:
bridge cable; ice accretion; Strouhal number; angle of attack; vortex shedding frequency
Fulltext is available at external website.
Influence of ice accretion at bridge rope on Strouhal number
The paper is concerned with the method and results of wind tunnel investigations of the/nStrouhal number (St) of a stationary iced cable model of cable-supported bridges with/nrespect to different ...
The numerical assessment of a full-scale truss reconstructed employing a traditional all-wooden joints
Milch, J.; Tippner, J.; Sebera, V.; Kunecký, Jiří; Kloiber, Michal; Navrátil, M.
2015 - English
The assessment of mechanical behaviour of all-wooden joints used in historical timber structures such as churches, castles etc. is currently paid a big attention in the Czech Republic, and Central Europe as a whole. The reasons are (a) a high number of such structures; (b) their significance to the national cultural heritage and maintenance for preserving their cultural value; and (c) missing information about global mechanical behaviour of joints and whole truss structures when loaded. Generally, valuable historical monuments need to be evaluated as regards the structure and safety of all timber elements in the structure for their future preservation [1]. The present paper shows a novel methodology for virtual assessment of mechanical behaviour used in a historically valuable gothic truss structure of St. James's Church in Brno, which is very valuable from both structural and architectural points of view. The church was constructed between1220 and 1724, the used styles including the Romanesque, the Gothic and the Neogothic. Also carpentry master Anton Ebenberger participated [2]. The aim of this paper was to describe the real loading of a joint that corresponds to the real function of a joint in the truss structure during the loading owing to new positions of replacement joints in the truss. Currently, the truss of St. James’s church shows large defects including decayed members; therefore, renovation is needed. The restoration of the truss should be carefully implemented in the structure and analyzed beforehand. Therefore, the numerical approaches based on FEM were used to evaluate the mechanical behaviour of the beam truss with a detailed 3D solid joint.
Keywords:
timber structures; all-wooden joints; mechanical behaviour
Fulltext is available at external website.
The numerical assessment of a full-scale truss reconstructed employing a traditional all-wooden joints
The assessment of mechanical behaviour of all-wooden joints used in historical timber structures such as churches, castles etc. is currently paid a big attention in the Czech Republic, and Central ...
High-performance and compatible lime mortars for extreme application in restoration, repair and preventive maintenance of architectural heritage: final report
Kabele, P.; Slížková, Zuzana
2015 - Czech
The final report describes progress and achieved results of the project, which was focused on development of new high-performance and compatible mortars for extreme application in restoration, repair and preventive maintenance of architectural heritage, development of numerical tools for their optimization and simulation and verification of their application on model historical objects. The materials were developed so as to achieve higher effectiveness and prolonged durability compared to classical lime mortars. Závěrečná zpráva projektu popisuje průběh řešení a dosažené výsledky projektu, zaměřeného na vývoj nových vysokohodnotných a kompatibilních vápenných malt pro extrémní použití při restaurování, opravách a preventivní údržbě architektonického dědictví, vytvoření nástrojů pro jejich optimalizaci a numerickou simulaci a ověření jejich aplikace na vybraných modelových historických objektech. Nově vyvinuté materiály dosahují zvýšené účinnosti a prodloužení životnosti ve srovnání s klasickými vápennými maltami.
Keywords:
lime mortars; pseudo-ductility; salt resistance; frost resistance; internal hydrophobicity; fiber reinforcement; cocciopesto; metakaolin; linseed oil; micromechanics-based material design
Available in digital repository of the ASCR
High-performance and compatible lime mortars for extreme application in restoration, repair and preventive maintenance of architectural heritage: final report
The final report describes progress and achieved results of the project, which was focused on development of new high-performance and compatible mortars for extreme application in restoration, repair ...
Strengtheninig of whitish degraded porous limestone by suspension of nanoparticles of calcium hydroxide in alcohol
Slížková, Zuzana; Frankeová, Dita
2015 - Czech
Limestone, which is damaged (degraded) in its surface layer, and having a suitable pore size, ie. that contain cracks or pores with a diameter greater than one micron, it is possible to consolidate by calcium hydroxide in the form of particles of a size of hundreds of nanometers. Suspension (also called dispersion, a colloidal sol) of nano-particles of calcium hydroxide in ethanol, may have different concentrations and can be applied to damaged limestone one or more times in various amounts, depending on its concentration and properties of the stone. The procedure specifies the limestone material tests carried out before the intervention and the possibility of minimizing whitish haze on the surface of the treated stone. Vápence, které jsou poškozeny (degradovány) ve své povrchové vrstvě, a které mají vhodnou velikost pórů, tzn. že obsahují póry nebo praskliny s průměrem větším než jeden mikrometr, je možné zpevnit konsolidačním prostředkem, který obsahuje hydroxid vápenatý ve formě částic o velikosti stovek nanometrů. Suspenze (nebo též disperze, koloidní roztok, sol) nano-částic hydroxidu vápenatého v ethanolu může mít různou koncentraci a může se aplikovat do poškozeného vápence jednou nebo vícekrát v různém množství, podle koncentrace prostředku a podle vlastností kamene. Uvedený postup specifikuje materiálové zkoušky vápence prováděné před zásahem i možnosti minimalizace vzniku bělavého zákalu na povrchu ošetřeného kamene.
Keywords:
limestone; strengthening; nanolime; calcium hydroxide dispersion
Available in a digital repository NRGL
Strengtheninig of whitish degraded porous limestone by suspension of nanoparticles of calcium hydroxide in alcohol
Limestone, which is damaged (degraded) in its surface layer, and having a suitable pore size, ie. that contain cracks or pores with a diameter greater than one micron, it is possible to consolidate by ...
Strengthening of historic lime plaster by dispersion of nanoparticles of calcium hydroxide in alcohol
Slížková, Zuzana; Frankeová, Dita
2015 - Czech
Preservation procedure suggests the technology of strengthening of the historic lime plasters, which is based on a liquid lime reinforcing agent impregnation - dispersions of nanoparticles of calcium hydroxide. The principle is in the use of new lime consolidant which thanks to the optimal concentration of lime (10 to 25 g / l), the lime particle size from 50 to 250 nm and the absence of water allows effective, compatible and economical reinforcing treatment during a relatively short time (1-3 weeks) . Preservation procedure is suitable for strengthening of plasters that contain pores or cracks larger than 1 micron. Památkový postup navrhuje technologii zpevnění historické vápenné omítky na stavebním objektu kulturního dědictví, jejíž podstatou je impregnace kapalným vápenným zpevňujícím prostředkem – disperzí nanočástic hydroxidu vápenatého. Podstata řešení je ve využití nového vápenného prostředku, který díky optimální koncentraci vápna (10-25g/l), velikosti vápenných částic 50-250 nm a absenci vody umožňuje efektivní, kompatibilní a šetrný zpevňující zásah během relativně krátké doby (1 až 3 týdny). Památkový postup je vhodný pro zpevňování omítek, které obsahují póry nebo praskliny větší než 1 μm.
Keywords:
lime plaster; consolidation; nanolime; calcium hydroxide dispersion
Available in a digital repository NRGL
Strengthening of historic lime plaster by dispersion of nanoparticles of calcium hydroxide in alcohol
Preservation procedure suggests the technology of strengthening of the historic lime plasters, which is based on a liquid lime reinforcing agent impregnation - dispersions of nanoparticles of calcium ...
Preparation of plaster with increased frost resistance for repair of historic buildings
Slížková, Zuzana; Frankeová, Dita; Nunes, Cristiana Lara; Janotová, Dana; Hauková, Petra
2015 - Czech
The methodology provides basic information on the preparation and use of lime-metakaolin mortar modified with linseed oil in order to increase the resistance of the mortar to freeze-thaw cycles and durability of mortar (plaster). The mortar will be used in the field of conservation of historic constructions. Metodika uvádí základní informace pro použití vápeno-metakaolinových omítek, vyznačujících se zvýšenou odolností vůči mrazovým cyklům. Je určena restaurátorům, projektantům, technologům a pracovníkům památkové péče pro využití při návrhu a provádění obnovy omítek na historických konstrukcích v nepříznivých klimatických podmínkách. Metodika předkládá informace o specifických vlastnostech vápenometakaolinových omítek, které jsou modifikovány hydrofobní přísadou (lněným olejem) za účelem prodloužení životnosti omítky.
Keywords:
lime plaster; lime-metakaolin mortar; mortar resistance; conservation; oil
Available in a digital repository NRGL
Preparation of plaster with increased frost resistance for repair of historic buildings
The methodology provides basic information on the preparation and use of lime-metakaolin mortar modified with linseed oil in order to increase the resistance of the mortar to freeze-thaw cycles and ...
Desing and production of specialized lime binders for restoration of monuments using historical technologies
Válek, Jan; Matas, Tomáš; Jiroušek, Josef; van Halem, Eveline; Hauková, Petra; Frankeová, Dita; Frankl, Jiří; Tomanová, Olga; Panáček, Michal
2015 - Czech
The methodological guideline supports the use of traditional lime materials for repair of historical buildings. It describes the main steps to be carried out when it is required to use a traditional lime mortar. The guideline provides an overview of the circumstances for using traditional technologies which are applied in the design and selection of lime binder and its treatment. It specifies essential procedures and principles that determine traditional production and processing of lime and recommends specific procedures for the lime processing and mortar production. The guideline is intended for architects, building engineers, cultural heritage conservators, conservation scientists, technologists, restorers and practitioners. Cílem metodiky je podpora využívání a opětovného zavedení tradičních vápenných materiálů při opravách historických staveb. Popisuje hlavní kroky, které je třeba uskutečnit v případě, že pro opravu historického objektu je vyžadována malta vyrobená za použití tradičních technologií. Metodika obsahuje přehled o okolnostech využití tradičních technologií, které se uplatní při návrhu a výběru vápenného pojiva a jeho zpracování. Upřesňuje zásadní postupy a principy, jež určují vybrané tradiční technologie výroby a zpracování vápna, a doporučuje konkrétní postupy při výrobě vápna, hašení za mokra, hašení na prach a hašení s pískem. Vychází ze známých postupů a znalostí publikovaných v odborné literatuře, které byly během projektu Calcarius teoreticky i prakticky ověřeny a zpřesněny. Metodika je určena zejména architektům, stavebním projektantům, památkovým pracovníkům, technologům a restaurátorům.
Keywords:
traditional lime production; lime technologies; lime slaking; lime putty; hot lime
Available in a digital repository NRGL
Desing and production of specialized lime binders for restoration of monuments using historical technologies
The methodological guideline supports the use of traditional lime materials for repair of historical buildings. It describes the main steps to be carried out when it is required to use a traditional ...
Strengthening of weak historic renders with traditional and innovated consolidation treatment
Slížková, Zuzana; Frankeová, Dita
2015 - English
The presented study was aimed to proof consolidation effects of different families of consolidants: inorganic agents (lime -based or silica-based solutions or sols), organic agents (silicic acid ester based consolidant) and their combination on the characteristics of weak mortars prepared in laboratory with different types of aggregates. Besides exploring consolidant-substrate interaction also the pozzolanic activity of the aggregate and the binder mortar component after reaction with lime (calcium hydroxide solution) was investigated in order to understand and describe the strengthening mechanism into consolidated mortars. As the study was based on experimental research, the production of mortar test specimens represented an important preliminary work. Different mortar components (various types of sand in terms of phase composition, clay, lime) and the same ratio of the aggregate and the binder were used in various mortar mixtures. Various mineralogical types of aggregate were used with the same grain size distribution (600 pieces of tubes of 40 mm in outer diameter, of the height of 40 mm and depth of 4 mm were prepared for testing the compressive strength, for the tension tests 550 thin plates of dimensions 40 mm x 100 mm x 4 mm were cast and 600 beams 20 x 20 x100mm were made for testing the flexural strength and other characteristics of reference and consolidated mortars). The sand used for mortar specimens was characterized by microscopic examination of thin section and also by X-ray diffraction, X-ray fluorescence spectroscopy and thermal analysis. The pozzolanic activity of the sands (reactivity with calcium hydroxide) was determined by means of the thermal analysis and supplemented by wet silicate analysis. The amount of the effective matter in the consolidant was the same for all agents per the square unit for all mortar types and specimen shape. One set of specimens was prepared as the reference set the second set was used for the evaluation.
Keywords:
lime mortar; lime render; consolidating products; lime water; nanolime; consolidation; strengthening
Available in a digital repository NRGL
Strengthening of weak historic renders with traditional and innovated consolidation treatment
The presented study was aimed to proof consolidation effects of different families of consolidants: inorganic agents (lime -based or silica-based solutions or sols), organic agents (silicic acid ester ...
High-performance and compatible lime mortars for extreme application in restoration, repair and preventive maintenance of architectural heritage: final report redacted
Kabele, P.; Slížková, Zuzana
2015 - Czech
The final report describes progress and achieved results of the project, which was focused on development of new high-performance and compatible mortars for extreme application in restoration, repair and preventive maintenance of architectural heritage, development of numerical tools for their optimization and simulation and verification of their application on model historical objects. The materials were developed so as to achieve higher effectiveness and prolonged durability compared to classical lime mortars. Závěrečná zpráva projektu popisuje průběh řešení a dosažené výsledky projektu, zaměřeného na vývoj nových vysokohodnotných a kompatibilních vápenných malt pro extrémní použití při restaurování, opravách a preventivní údržbě architektonického dědictví, vytvoření nástrojů pro jejich optimalizaci a numerickou simulaci a ověření jejich aplikace na vybraných modelových historických objektech. Nově vyvinuté materiály dosahují zvýšené účinnosti a prodloužení životnosti ve srovnání s klasickými vápennými maltami.
Keywords:
lime mortars; pseudo-ductility; salt resistance; frost resistance; internal hydrophobicity; fiber reinforcement; cocciopesto; metakaolin; linseed oil; micromechanics-based material design
Available in digital repository of the ASCR
High-performance and compatible lime mortars for extreme application in restoration, repair and preventive maintenance of architectural heritage: final report redacted
The final report describes progress and achieved results of the project, which was focused on development of new high-performance and compatible mortars for extreme application in restoration, repair ...
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