Vesna Zalar | University of Ljubljana (original) (raw)

Papers by Vesna Zalar

Acta Biologica Slovenica, Nov 30, 2019

Sustainability, Jun 14, 2024

Materials

This paper deals with the characterisation of cementitious materials from selected cultural herit... more This paper deals with the characterisation of cementitious materials from selected cultural heritage structures in Slovenia. The mineralogical–petrographic compositions of an aggregate, a type of binder and secondary minerals were studied via electron microscopy and X-ray powder diffraction. The porosity and pore network were determined using a mercury porosimeter. The results show that the aggregate of the samples was highly diverse, ranging from limestone, dolomite, quartz, feldspar and mica. The binder of the investigated samples was cementitious; either ordinary Portland cement was used, or ordinary Portland cement blended with ground granulated blast furnace slag was used. Some samples consisted of cement–lime binders. The investigated examples entailing cement materials for their construction contribute to a better understanding of the technology used to prepare historical cementitious and cement–lime mixtures.

Materials Characterization, Nov 1, 2011

This study deals with the characterization of mortars collected from bath complex of the Roman vi... more This study deals with the characterization of mortars collected from bath complex of the Roman villa rustica from an archeological site near Mošnje (Slovenia). The mortar layers of the mosaics, wall paintings and mortar floors were investigated. A special aggregate consisting of brick fragments was present in the mortars studied. The mineralogical and petrographic compositions of the mortars were determined by means of optical microscopy, X-ray powder diffraction and FTIR spectroscopy. Analysis of aggregate-binder interfaces using SEM-EDS revealed various types of reactivity rims. In order to assess the hydraulic characteristics of the mortars, the acid-soluble fractions were determined by ICP-OES. Furthermore, the results of Hg-porosimetry and gas sorption isotherms showed that mortars with a higher content of brick fragments particles exhibited a higher porosity and a greater BET surface area but a lower average pore diameter compared to mortars lacking this special aggregate.

International Journal of Environmental Research and Public Health

The environmental properties of three geotechnical composites made by recycling wastes were inves... more The environmental properties of three geotechnical composites made by recycling wastes were investigated on a laboratory scale and in the field with the use of lysimeters designated for the revitalization of degraded mining sites. Composites were prepared by combining the mine waste with paper-mill sludge and foundry sand (Composite 1), with digestate from municipal waste and paper ash (Composite 2), and with coal ash, foundry slag and waste incineration bottom ash (Composite 3). The results of laboratory leaching tests proved that Composites 1 and 3 are environmentally acceptable, according to the legislative limits, as the potentially hazardous substances were immobilized, while in Composite 2, the legislative limits were exceeded. In the field lysimeters, the lowest rate of leaching was determined for optimally compacted Composites 1 and 3, while for Composite 2 the leaching of Cu was high. This study proved that optimally installed Composites 1 and 3 are environmentally acceptab...

EGU General Assembly Conference Abstracts, Apr 1, 2017

Construction and Building Materials, 2016

h i g h l i g h t s Characterization of slag derived from stainless steelmaking refining processe... more h i g h l i g h t s Characterization of slag derived from stainless steelmaking refining processes. Secondary stainless steel slag contain hydraulic phases, predominantly calcium aluminates. Study of cement composites in which cement is replaced by secondary stainless steel slag. Investigation of strength development, hydration products, and porosity. Secondary stainless steel slag is a promising supplementary cementitious material.

Materiali in Tehnologije

ABSTRACT

Applied Sciences

Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation effi... more Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation efficiency after longer periods has not been reported. To gain insights into the mechanisms of immobilization of cadmium (Cd), lead (Pb), and znic (Zn), a study was performed in the laboratory experiment in uncontaminated, artificially contaminated, and remediated soils, and these soils treated with sulfate, to mimic conditions in contaminated soil from zinc smelter site. Remediation was performed by mixing contaminated soil with paper-ash to immobilize Cd, Pb, and Zn in the geotechnical composite. Partitioning of Cd, Pb, and Zn was studied over one year in seven-time intervals applying the sequential extraction procedure and complementary X-ray diffraction analyses. This methodological approach enabled us to follow the redistribution of Cd, Pb, and Zn over time, thus, to studying immobilization mechanisms and assessing the remediation efficiency and stability of newly formed mineral phases....

The holistic approach to environment, 2021

The treated sewage sludge under consideration is a hygienized biodegradable waste in the form of ... more The treated sewage sludge under consideration is a hygienized biodegradable waste in the form of pellets. It can be used as a fertilizer, but only for spreading on non-agricultural land. Regarding “waste to energy” philosophy, the specification of pellets as an alternative solid fuel according to EN 15359 resulted in “NCV4; Cl1; Hg3-4” class. The major problem regarding the final pellets utilization is the lack of facilities for energy and material recovery from this type of waste in Slovenia. According to the newest legislation regarding the waste management, a product status for residues generated in combustion and pyrolysis of pellets on a laboratory and semi-pilot scale was not achieved. The holistic approach to final pellets utilization was studied and regarding the full-scale level of self-sufficient sewage sludge management in Slovenia, some legislative provisions become significant obstacles.

Toxics

Old metallurgical dumps across Europe represent a loss of valuable land and a potential threat to... more Old metallurgical dumps across Europe represent a loss of valuable land and a potential threat to the environment, especially to groundwater (GW). The Javornik electric arc furnace (EAF) and ladle slag heap, situated in Slovenia, was investigated in this study. The environmental impact of the slag heap was evaluated by combining leaching characterization tests of landfill samples and geochemical modelling. It was shown that throughout the landfill the same minerals and sorptive phases control the leaching of elements of potential concern, despite variations in chemical composition. Although carbonation of the disposed steel slags occurred (molar ratio CO3/(Ca+Mg) = 0.53) relative to fresh slag, it had a limited effect on the leaching behaviour of elements of potential concern. The leaching from the slag heaps had also a limited effect on the quality of the GW. A site-specific case, however, was that leachates from the slag heap were strongly diluted, since a rapid flow of GW fed fro...

The fundamental objective of this study was to define such a cement composite with the addition o... more The fundamental objective of this study was to define such a cement composite with the addition of white (ladle) slag, which will provide functionality for selected purposes and furthermore, prevent the leaching of toxic elements into the environment. The recovery (recycling) of secondary metallurgical slags from stainless steel production has an important synergistic impact on the environment. In this study, detailed characterization of slag derived from two different ladle refining processes of stainless steel production has been performed. In order to assess its potential for use as a supplementary cementitious material, slag cement composites as well as slag itself were investigated. A comparative study of reference cement composites and cement composites to which a conventional supplementary cementitious material (limestone filler) had been added, was also performed. The results showed that the slag contains hydraulic phases to a total amount of about 50 %. Calcium aluminates a...

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An important step in secondary metallurgy of stainless steel is ladle metallurgy. Ladle slag is a... more An important step in secondary metallurgy of stainless steel is ladle metallurgy. Ladle slag is a by-product of ladle refining, typically specific for each steelmaking plant. Industrial secondary materials can be used for different applications, including construction and civil engineering. The use of industrial by-products requires the knowledge of the characteristics of the materials. Using metallurgical by-products that fulfil the relevant requirements can save natural resources, as well as helping to avoid impairment of the landscape through their excavation and, thus, minimizing the adverse landfilling of such materials. This paper provides an overview of possible uses of ladle slag (the slag from a ladle furnace and vacuum-oxygen-decarburization processes). As a preliminary research, ladle slag has been investigated using SEM/EDS. The commonly known hydraulic minerals, such as tricalcium aluminate, mayenite, tricalcium silicate and dicalcium silicate, were detected in this ana...

Forensic examinations can be performed on well-preserved objects to detect material traces. A lar... more Forensic examinations can be performed on well-preserved objects to detect material traces. A large number of objects were discovered in the cave Brezno v Debliških livadah, which were dumped in the cave in May and June 1945. Among the discovered material there were also military canteens (drinking bottles). Some canteens still contained liquids, and some even a semi-hard, gel precipitate. The liquid and precipitate from the analyzed canteens contained metals that were most likely leached from the metal containers. The corrosion of the canteens is indicated by the presence of a hematite mineral. The content of canteens contained some dissolved organic matter (Total Organic Carbon, TOC, in the liquid = 9.22 mg/l, in the liquid ACTA BIOLOGICA SLOVENICA LJUBLJANA 2019 Vol. 62, Št. 2: 67–77 68 Acta Biologica Slovenica, 62 (2), 2019 from extracted precipitate = 34.1 mg/l), some microbial biomass and relatively high nitrate concentrations (240 mg/l in liquid, 55 mg/l in extracted precipit...

Journal of Cleaner Production

Abstract Remediation of contaminated soil can be performed by using various techniques, which mus... more Abstract Remediation of contaminated soil can be performed by using various techniques, which must be adequately tailored for each specific case. The aim of this research is to critically evaluate the potential use of red mud and paper ash and a combination of the two as immobilization additives for the remediation of contaminated soil from one of the most polluted sites in Slovenia. The proposed procedure involves the preparation of geotechnical composites made from contaminated soil and mixed with 25 wt% of immobilization additives and an optimal quantity of water to achieve consistency, at which maximum compaction according to the Proctor Compaction Test procedure can be achieved. The results reveal a positive, time-dependent trend for the immobilization of potentially toxic elements in the composite with paper ash, because of the formation of the new hydration products with potentially toxic elements. In a composite containing only red mud, potentially toxic elements were immobilized by sorption mechanisms with no general time-dependent trends. The composite with a combination of additives demonstrates the remediation characteristics of both red mud and paper ash. Using this approach excavated contaminated soil, red mud and paper ash can be successfully recycled in the proposed composites, which can be beneficially used in situ for rehabilitation of contaminated sites. Nevertheless, mobilization of some potentially toxic elements at high pHs may represent a limiting factor and has to be taken into the consideration when a combination of red mud and paper ash is used as immobilization additive.

Scientific Reports

This study introduces a novel geotechnical composite material comprising two types of fill materi... more This study introduces a novel geotechnical composite material comprising two types of fill material sourced from the paper industry—deinking paper sludge ash (DPSA) and deinking paper sludge (DPS). Five composites with different DPSA and DPS contents were investigated. Two composites were selected for further analyses. The technology and procedure for composite installation were implemented in field tests. The composites with 80% and 70% DPSA exhibited the elasticity required to withstand minor landslide slip deformations, in addition to achieving sufficiently high values of uniaxial compressive strength. The composites had a low maximum dry density value, which led to fewer settlements in the entire support structure. The enhanced shear characteristics can enable the construction of a thinner retaining wall. The delay between preparation and installation of the composites was further investigated. The field tests confirmed that the composites with 80% and 70% DPSA can be installed ...