23 research outputs found
Deterioration of the black Drenov GriÄ limestone on historical monuments (Ljubljana, Slovenia)
The black limestone from Drenov GriÄ quarry (Central Slovenia) is considered one of the most beautiful Slovenian natural stones due to its typical color. The limestone was characterized from mineralogical, chemical, and petrophysical points of view. Furthermore, deterioration phenomena of the limestone from two monuments exposed to indoor and outdoor environments were studied. In situ investigation of two monuments by means of monument mapping has identified several types of deterioration phenomena, such as granular disintegration, flaking, crumbling, efflorescences, crusts, and the presence of microorganisms. Samples were characterized using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS), X-Ray Powder Diffraction Analysis (XRD), porosity accessible to water under vacuum, capillary absorption, Mercury porosimetry (MIP), and Ar-sorption. Although very low values of porosity of the fresh stone as well as slow capillary kinetics were determined, both monuments showed severe deterioration as a consequence of the transport and precipitation of soluble salts within the stone
Heritage Stone 7. Pohorje Granodiorite â One of the Most Significant Slovenian Natural Stones
Granodiorite from the Pohorje Mountains (northeastern Slovenia) is considered the highest quality natural stone in Slovenia. Pohorje granodiorite is a grey, calc-alkaline igneous rock of Miocene age (18.7 Ma) that is distinguished by thick white apliteâpegmatite veins. It mainly consists of plagioclase, quartz, and K-feldspar, subsidiary biotite and a small amount of hornblende. It is characterized by high density, low water absorption, and low porosity, so that it exhibits high frost and salt resistance, as well as a high compressive strength and a very high flexural strength. It is widely recognized throughout the country for its durability and decorative white veins, and is the most frequently used natural stone in Slovenia today. It is mainly used as paving and cladding material for residential buildings, churches, and other structures, as well as in public areas, where it adds special character to many of the larger towns and cities. Several important buildings, some of which have been declared cultural monuments of national importance, are also decorated with this stone, including the Slovenian Parliament, the Republic Square business complex, and the Faculty of Law of the University of Ljubljana, all of which are located in Ljubljana. Since 1940, Pohorje granodiorite has also been widely used by sculptors in various monuments and fountains. RĂSUMĂLe granodiorite des montagnes de Pohorje (nord de la SlovĂ©nie) est considĂ©rĂ© comme la meilleure pierre naturelle de SlovĂ©nie. Le granodiorite de Pohorje est une roche ignĂ©e grise, calco-alcaline du MiocĂšne (18,7 Ma) qui se distingue par la prĂ©sence dâĂ©pais filons de pegmatites dâaplite blanche. Il se compose principalement de plagioclase, de quartz et de feldspath potassique, de biotite accessoire et dâune petite quantitĂ© d'amphibole. Elle est caractĂ©risĂ©e par une densitĂ© Ă©levĂ©e, un faible coefficient dâimbibition, et une porositĂ© faible, de sorte qu'elle prĂ©sente une haute rĂ©sistance au gel et au sel, ainsi quâune rĂ©sistance Ă©levĂ©e Ă la compression et une rĂ©sistance trĂšs Ă©levĂ©e Ă la flexion. Elle est trĂšs connue dans tout le pays pour sa durabilitĂ© et ses filons dĂ©coratifs blancs, et câest la pierre naturelle la plus frĂ©quemment utilisĂ©e en SlovĂ©nie de nos jours. Elle est principalement utilisĂ©e comme matĂ©riau de pavage et de revĂȘtement pour les bĂątiments rĂ©sidentiels, les Ă©glises et autres constructions, ainsi que dans les espaces publics, oĂč elle donne un caractĂšre distinctif aux grands villages et aux villes. Plusieurs bĂątiments importants, dont certains ont Ă©tĂ© dĂ©clarĂ©s monuments culturels d'importance nationale, sont Ă©galement dĂ©corĂ©es avec cette pierre, y compris le Parlement slovĂšne, le complexe d'affaires Place de la RĂ©publique, et la FacultĂ© de droit de l'UniversitĂ© de Ljubljana, lesquels sont tous situĂ©s Ă Ljubljana. Depuis 1940, le granodiorite de Pohorje a aussi Ă©tĂ© beaucoup utilisĂ© par les sculpteurs dans divers monuments et fontaines.Traduit par le Traducteu
Reactivity tests for supplementary cementitious materials: RILEM TC 267-TRM phase 1
A primary aim of RILEM TC 267-TRM: âTests for Reactivity of Supplementary Cementitious Materials (SCMs)â is to compare and evaluate the performance of conventional and novel SCM reactivity test methods across a wide range of SCMs. To this purpose, a round robin campaign was organized to investigate 10 different tests for reactivity and 11 SCMs covering the main classes of materials in use, such as granulated blast furnace slag, fly ash, natural pozzolan and calcined clays. The methods were evaluated based on the correlation to the 28 days relative compressive strength of standard mortar bars containing 30% of SCM as cement replacement and the interlaboratory reproducibility of the test results. It was found that only a few test methods showed acceptable correlation to the 28 days relative strength over the whole range of SCMs. The methods that showed the best reproducibility and gave good correlations used the R3 model system of the SCM and Ca(OH)2, supplemented with alkali sulfate/carbonate. The use of this simplified model system isolates the reaction of the SCM and the reactivity can be easily quantified from the heat release or bound water content. Later age (90 days) strength results also correlated well with the results of the IS 1727 (Indian standard) reactivity test, an accelerated strength test using an SCM/Ca(OH)2-based model system. The current standardized tests did not show acceptable correlations across all SCMs, although they performed better when latently hydraulic materials (blast furnace slag) were excluded. However, the Frattini test, Chapelle and modified Chapelle test showed poor interlaboratory reproducibility, demonstrating experimental difficulties. The TC 267-TRM will pursue the development of test protocols based on the R3 model systems. Acceleration and improvement of the reproducibility of the IS 1727 test will be attempted as well
Estimation of measurement uncertainty for determination of sulphate content in cement by an alternative approach
The precise and accurate determination of sulphate levels in cement is of utmost importance due to the potential occurrence of internal sulphate attack in concrete, which affects the latterâs durability, and thus, also the safety of concrete constructions. The estimated measurement uncertainty provides a level of confidence in the experimental results, and enables the comparison of data, both between different laboratories and between different methods. This paper presents an alternative approach to the estimation of measurement uncertainty in the determination of sulphate in cement, based on the use of proficiency testing data. The calculations used in this procedure refer to the estimation of reproducibility within-laboratory component of the analysis of control samples, as well as of the bias component of sulphate content data for different types of Portland cement derived from several proficiency testing trials
Mechanical and microstructural characterization of geopolymer synthesized from low calcium fly ash
This study deals with the mechanical and microstructural characterization of
geopolymers synthesized from locally available fly ash. A low calcium fly ash
was activated using a sodium silicate solution. Samples were characterized by
means of flexural and compressive tests, Fourier Transform Infrared (FTIR)
spectroscopy, X-ray powder diffraction (XRD), and scanning electron
microscopy (SEM). Porosity and pore size distributions were identified using
mercury intrusion porosimetry and gas sorption. The compressive strength of
the produced geopolymers, which is in the range of 1.6 to 53.3 N/mm2, is
strongly related to the water content as well as SiO2/Na2O mass ratio of an
alkali activator. The compressive strength significantly increased with
decreases in the water content and increased silicon concentration used for
the synthesis of geopolymers
Evaluation of Ash Pozzolanic Activity by Means of the Strength Activity Index Test, Frattini Test and DTA/TG Analysis
The pozzolanic activity of five different types of ash was studied using various direct and indirect methods. In addition to strength activity index (SAI) determination and the Frattini test, ash pozzolanicity was assessed via differential thermal and thermogravimetric analyses (DTA/TG) after curing for 7, 28 and 90 days. The results showed that, due to their respective mineralogical, chemical and physical characteristics, the ashes exhibited different levels of pozzolanic activity in terms of the amount of lime with which they could chemically bind, as well as reaction kinetics. Although SAI and Frattini test results were not in agreement in the case of some of the ashes, DTA/TG analysis revealed that a certain amount of portlandite was consumed, thus confirming the occurrence of a pozzolanic reaction. The results also showed that ashes with higher amounts of reactive SiO2 were more reactive, while those with higher BET surface areas displayed a faster pozzolanic reaction rate
Building of the Al-Containing secondary raw materials registry for the production of low CO2 mineral binders in South-Eastern European region
The bottleneck in the process for increasing production of low CO2 mineral binders, based on BCSA (belite sulfoaluminate) clinkers, is the availability of Al-rich raw materials. For that purpose, a new registry of Al-containing secondary mineral residues (industrial and mine waste) has been developed and is presented in this paper. The methodology of creating the registry consists of three main steps: Gathering ideas, consolidation of ideas, and implementation. In order to achieve this, the following methodology was adopted: Analysis of similar registries by potential end-users and seeking potential solutions and tools to be used, and conducting 3 rounds of stakeholder consultations via workshops in order to determine crucial parameters and features the registry needs to contain. The key discussion points were about which data the registry needs to contain, who shall be the potential users, and what are the stakeholderÊŒs expectations from the registryÊŒs portal. Potential individual registry variables were identified as being relevant/irrelevant or available/unavailable, and potential solutions for the registrys sustainability were explored. Each Al-rich waste/residue data entry is divided into 10 slots, describing legal status, location, quantities, chemical (REE included), mineralogical, physical and radiological properties, life-cycle assessment, additional data, and data relevancy. The registry will act as a matchmaking tool between producers/holders of Al-rich secondary raw materials and potential producers of cement clinkers
Morphological characteristic and causes of color for the crystals of calcite from Liboje
The crystals of calcite from the quarry Liboje were investigated and compared with calcite crystals from
other quarries in the surrounding area of Celje. In calcite crystals from the Liboje quarry, the crystal form of
flat rhombohedron faces were predominant (012). At a later stage of crystallization, the crystal form of steep
rhombohedrons prevailed. They crystallised from hot aqueous solution in the fissures within carbonate rocks. It was
ascertained that the crystal growth of calcite from Liboje was related to at least two events in geological history. The
colour of calcite crystals is associated with both the solid phase inclusions, such as manganese oxide and goethite,
and by liquid inclusions - water. Mineral composition of inclusions was determined by Raman microspectroscopy
A raman microspectroscopy-based comparison of pigments applied in two gothic wall paintings in Slovenia
The present study deals with the characterisation of pigments used in two overlaid gothic
wall paintings from the former 13th century Minorite church of St. Francis of Assisi
(Koper, Slovenia), in order to define differences in the technologies used. Paint layer
samples were analysed via Raman microspectroscopy, supported by SEM/EDS and FTIR analysis, when necessary. The results revealed that the 14th century mural was painted
mainly a fresco with final elements a secco, a technique typical of Italian mediaeval
wall painting. In contrast, the 15th century painting was executed mostly a secco, a
technique often applied in Northern Europe and the Alpine region. The differences
between the two paintings are especially obvious in the pigments applied. While the
earlier painting is characterised by azurite, carbon black, red and yellow ochres, lime
white and green earth, the palette used for the younger painting is much broader. In
addition to red and yellow ochres, carbon black and lime white, lead pigments such
as lead white, red lead and lead-tin yellow type I were also determined, as well as a
number of expensive pigments including cinnabar, azurite and malachite. Also found
in the younger painting was the rare orange yellow pigment vanadinite. In both layers,
azurite was applied a secco for the background area. Gilding was confirmed in both
layers, carried out as application of gold leaves on red bole (in the earlier mural) and
on mordant (on a younger, superimposed (overlaid painting), which is quite exclusive
and rare for Slovene mediaeval painting. In the younger layer also a use of tin foil for
secondary elements was discoveredThis work was financially supported by the Municipality of Koper within the framework of the conservation restoration project âMinorite church of St. Francis of Assisiâ and Slovenian Research Agency Programme Group P2-0237.Peer reviewe