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Iskalni niz: "avtor" (Mojca Božič) .

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1.
Stabilization of river dredged sediments by means of alkali activation technology
Karmen Fifer Bizjak, Lea Žibret, Mojca Božič, Boštjan Gregorc, Vilma Ducman, 2024, izvirni znanstveni članek

Povzetek: Purpose Alkali activation process has been applied to fresh river clay-rich sediments in order to increase their mechanical properties and make them suitable for soil stabilization. Materials and methods Dredged sediments were mixed with up to 30 mass percent (ma%) of fly ash (FA) or ladle slag (LS) and after curing for 3 days at 60 °C, the bending and compressive strength have been determined. The mixtures which exhibited the highest strengths were further optimized for being used in soil stabilization. For this purpose, the sediment was stabilized with 4 ma% of quicklime (QL) and after 1 h 30 ma% of FA with alkali activator was added and cured for 1, 7 and 28 days. Results The stabilized sediment has a significantely better geomechanical performance in comparison with the sediment alone. Stabilizing the dredged sediment using alkali activation technology provides high enough strengths to eventually make it suitable for anti-flood embankments. Conclusions The results confirmed the suitability of the investigated technology for soil stabilization.
Ključne besede: river sediment, alkali activated materials, ladle slag, fly ash, mechanical strength, soil stabilization
Objavljeno v DiRROS: 09.09.2024; Ogledov: 318; Prenosov: 4723
.pdf Celotno besedilo (1,41 MB)
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Evaluation of sediments from the river Drava and their potential for further use in the building sector
Vilma Ducman, Karmen Fifer Bizjak, Barbara Likar, Mitja Kolar, Ana Robba, Jernej Imperl, Mojca Božič, Boštjan Gregorc, 2022, izvirni znanstveni članek

Povzetek: Sedimentation is a naturally occurring process of allowing particles in water bodies to settle out of the suspension under a gravity effect. In this study, the sediments of the Drava River were fully investigated to determine the heavy metal concentrations along the river and their potential reuse in the construction sector. Naturally dehydrated sediments from the Drava River were tested as an additive for the production of fired bricks. The dredged sediments were used as a substitute for natural brick clay in amounts up to 50% by weight, and it was confirmed that up to 20% by weight of the added sediment could be used directly in the process without critically affecting performance. Finally, the naturally dehydrated sediments were also evaluated for their use as a filling material in the construction of levees. The natural moisture content of the dehydrated sediment was too high for it to be used without additives, so quicklime was added as an inorganic binder. The test results showed an improvement in the geotechnical properties of the material to such an extent that it is suitable as a filling material for levees.
Ključne besede: sediment, pollution, clay industry, soil stabilization, open access
Objavljeno v DiRROS: 31.05.2023; Ogledov: 734; Prenosov: 364
.pdf Celotno besedilo (3,20 MB)
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4.
Drava river sediment in clay brick production : characterization, properties, and environmental performance
Mojca Božič, Lea Žibret, Davor Kvočka, Alenka Mauko Pranjić, Boštjan Gregorc, Vilma Ducman, 2023, izvirni znanstveni članek

Povzetek: The ever-growing worldwide demand for fired clay brick has resulted in the shortage of clay in many parts of the world. Therefore, there is a need to look for more sustainable alternative materials for the brick manufacturing. This study has investigated the potential use of the untreated Drava River sediment as a substitute material for clay in the production of fired bricks, with the research being conducted at both laboratory and industrial level. At the laboratory level, brick specimens were prepared by mixing clay with different river sediment proportions (ranging from 10 to 50 wt%) and were fired at 950 °C, with microstructural and various physical–mechanical properties being analyzed. Elevated carbonate content in Drava river sediment results in higher weight loss during firing at temperatures up to 950 °C, comparing to firing pure brick-making clay. Consequently, the addition of sediment increases porosity of fired bricks, which results in lowering of their mechanical properties. Results reveal that the compressive strength of the pure clay sample was 79.5 MPa, while the compressive strength of the sample with the addition of river sediment from 10 wt% to 50 wt% decreased from 73.9 MPa to 26.2 MPa, respectively. Despite the lower compressive strength, the 26.2 MPa is still above the limit value of 10 MPa specified in the standard EN 772–1 [1]. At the industrial level, hollow clay bricks were prepared with 20 wt% of the river sediment and fired in a tunnel kiln. Inclusion of the river sediment also decreased compressive strength from 38 MPa for pure mixture to 26 MPa for 20 wt% of the sediment addition, confirming usability of Drava sediment in brick production. In addition, LCA study has been conducted to evaluate the environmental impacts associated with the industrial production of classic bricks and bricks with the addition of the river sediment. The obtained results have shown that the bricks made with the addition of the Drava River sediment are sustainable and environmentally friendly and meet all the requirements specified in the relevant regulatory standard.
Ključne besede: sediments, clay masonry units, LCA, properties
Objavljeno v DiRROS: 30.05.2023; Ogledov: 704; Prenosov: 506
.pdf Celotno besedilo (4,76 MB)
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5.
Clay rich river sediments calcined into precursors for alkali activated materials
Lea Žibret, Wolfgang Wisniewski, Barbara Horvat, Mojca Božič, Boštjan Gregorc, Vilma Ducman, 2023, izvirni znanstveni članek

Povzetek: Alkali activated materials (AAMs), a potential alternative to cement-based products or ceramics, can incorporate large amounts of currently landfilled aluminosilicate rich materials such as calcined clay-rich river sediments collected at hydropower plant dams. Untreated fresh sediment and untreated aged sediment intended to serve as AAM precursors were calcined to increase their amorphous content, then activated by Na or K-based silicate or hydroxide solutions and cured at 60 ◦C for three days. Up to 30 mass % (ma%) of fly ash (FA) or ladle slag (LS) increased the mechanical performance. The phase composition and microstructure are analyzed using X-ray diffraction, fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and mercury intrusion porosimetry to gain further insight into how the additives influence the final properties of the resulting AAMs. The main crystalline components of the prepared AAMs are quartz, illite/muscovite and feldspar. The amorphous content reaches up to 52.5 ma% in the Na-activated AAMs and up to 48.8 ma% in K-activated AAMs. The acquired results confirm the suitability of the investigated sediments as sole precursors for AAMs. The mechanical properties of the AAMs can be improved by adding FA and/or LS.
Ključne besede: sediments, alkali activated materials, properties
Objavljeno v DiRROS: 30.05.2023; Ogledov: 686; Prenosov: 571
.pdf Celotno besedilo (4,71 MB)
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6.
Laboratorijske preiskave pri protitrombotičnem zdravljenju
Mojca Božič, 2020, samostojni strokovni sestavek ali poglavje v monografski publikaciji

Ključne besede: protitrombotično zdravljenje, dabigatran, onkologija
Objavljeno v DiRROS: 06.04.2021; Ogledov: 1644; Prenosov: 401
.pdf Celotno besedilo (67,55 KB)

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