11. Using recycled material from the paper industry as a backfill material for retaining walls near railway linesKarmen Fifer Bizjak, Barbara Likar, Stanislav Lenart, 2021, izvirni znanstveni članek Povzetek: The construction industry uses a large amount of natural virgin material for different geotechnical structures. In Europe alone, 11 million tonnes of solid waste is generated per year as a result of the production of almost 100 million tonnes of paper. The objective of this research is to develop a new geotechnical composite from residues of the deinking paper industry and to present its practical application, e.g., as a backfill material behind a retaining structure. After different mixtures were tested in a laboratory, the technology was validated by building a pilot retaining wall structure in a landslide region near a railway line. It was confirmed that a composite with 30% deinking sludge and 70% deinking sludge ash had a high enough strength but experienced some deformations before failure. Special attention was paid to the impact of transport, which, due to the time lag between the mixing and installation of the composite, significantly reduced its strength. The pilot retaining wall structure promotes the use of recycled materials with a sustainable design, while adhering to government-mandated measures.
Ključne besede: paper sludge ash, deinking sludge, paper industry, backfill material, retaining wall
Objavljeno v DiRROS: 04.07.2023; Ogledov: 250; Prenosov: 154
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12. Valorized deinking paper residue as fill material for geotechnical structuresKarmen Fifer Bizjak, Barbara Likar, Ana Mladenovič, Vesna Zalar Serjun, 2021, izvirni znanstveni članek Povzetek: 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 on the construction site 4 h and even 24 h after mixing. In 2018, a retaining wall structure with 70% DPSA and 30% DPS was successfully implemented near a railway line using conventional technology as followed-up research to the herein presented study. Results have been derived from work performed in the scope of the H2020 Paperchain project in which novel circular economy models centered on the valorization of the waste streams generated by the pulp and paper industry as secondary raw material for several resource-intensive sectors, including the construction sector, have been developed. Environmental benefits are savings in natural raw materials, reduction of landfill disposal as well as CO2 emission reduction.
Ključne besede: deinking paper sludge ash, deinking paper sludge, secondary resources, fill material, geotechnical structure, landslide, open access
Objavljeno v DiRROS: 04.07.2023; Ogledov: 255; Prenosov: 206
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13. Environmental impacts and immobilization mechanisms of cadmium, lead and zinc in geotechnical composites made from contaminated soil and paper-ashMarija Đurić, Primož Oprčkal, Vesna Zalar Serjun, Alenka Mauko Pranjić, Janez Ščančar, Radmila Milačič, Ana Mladenovič, 2021, izvirni znanstveni članek Povzetek: 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. Cd, Pb, and Zn were effectively immobilized by precipitation of insoluble hydroxides after the addition of paper-ash and by the carbonization process in insoluble carbonate minerals. After remediation, Cd, Pb, and Zn concentrations in the water-soluble fraction were well below the limiting values for inertness: Cd by 100 times, Pb by 125 times, and Zn by 10 times. Sulfate treatment did not influence the remediation efficiency. Experimental data confirmed the high remediation efficiency and stability of insoluble Cd, Pb, and Zn mineral phases in geotechnical composites.
Ključne besede: cadmium, lead, zinc, contaminated soil, paper ash, immobilization mechanisms
Objavljeno v DiRROS: 04.07.2023; Ogledov: 331; Prenosov: 220
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14. Characterizing the interfacial zones of fly ash based alkali activated adhesives to various substratesWolfgang Wisniewski, Vilma Ducman, 2022, izvirni znanstveni članek Povzetek: Alkali Activated Materials (AAMs) are important potential substitutes for cement in many materials. The AAMs presented here are based on industrial ground granulated blast furnace slag (GGBFS) and fly ash (FA). They are tested for their suitability as adhesives for joining concrete, ceramic tiles, a wood-based geopolymer (WGP) and a high density geopolymer (HDGP). After mixing multiple batches and performing preliminary tests of the resulting shrinkage, bending-, compressive- and pull-of-strengths to standard ceramic tiles, selected mixtures are tested for their open time and applied to bond intended substrates. The interfacial zones (ITZ) of an AAM containing additional KOH and the most comparable KOH-free AAM to concrete, ceramic tiles, WPG and HDGP are subsequently characterized in detail using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). Both mechanical interlocking and areas of probable chemical bonding are identified.
Ključne besede: adhisive, fly ash, ITZ, pull of test, open ccess
Objavljeno v DiRROS: 21.06.2023; Ogledov: 311; Prenosov: 220
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15. Technical and radiological characterisation of fly ash and bottom ash from thermal power plantEmilija Fidanchevski, Biljana Angjusheva, Vojo Jovanov, Pece Murtanovski, Ljubica Vladiceska, Nikolina Stamatovska Aluloska, Jelena Krneta Nikolić, Andrej Ipavec, Katarina Šter, Maruša Mrak, Sabina Dolenec, 2021, izvirni znanstveni članek Povzetek: Huge quantities of fly ash and bottom ash are generated from thermal power plants and it presents great concern for country, mainly due to the environmental effects. In this study, fly ashes and bottom ash were characterized from technical and radiological aspects. Health effect due to the activity of radionuclides 226Ra, 232Th and 40K was estimated via radium equivalent activity (Raeq), external hazards index (Hex), the external absorbed dose rate (D) and annual effective dose rate (EDR). The specific surface area (40.25 m2 g−1), particle density (1.88 g cm−3) and LOI (23.49%) were typical for bottom ash. Siliceous fly ash contained 32% reactive silica. The annual effective dose rate for all ashes is ≤ 0.2 mSv y−1. Both, fly ash and bottom ash present potential secondary raw materials to be used for building purposes as result of their technological and radiological assessment.
Ključne besede: fly ash, bottom ash, gamma spectrometry, building materials
Objavljeno v DiRROS: 22.05.2023; Ogledov: 285; Prenosov: 137
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16. Potential usage of hybrid polymers binders based on fly ash with the addition of PVA with satisfying mechanical and radiological propertiesMiljana Mirković, Ljiljana Kljajević, Sabina Dolenec, Miloš Nenadović, Vladimir Pavlović, Milica Rajačić, Snežana B. Nenadović, 2021, izvirni znanstveni članek Povzetek: Since recycled technologies usage is mandatory for environmental safety, and in this regard, it is important to examine new materials that can be used in construction and are primarily produced from fly ash. In addition to characteristics such as hardness and compressive strength, the given materials must also be radiologically and environmentally safe. The main concept of engineered geopolymer gel composites based on fly ash residues is focused on developing binder materials via gel formation processes that can replace ordinary cement materials. This study is unique in researching the potential use of fly ash from the Nikola Tesla thermal power plant in Serbia, where the hybrid geopolymeric materials synthesized from fly ash are experimentally examined with the addition 1 wt% and 2 wt% of polyvinyl alcohol (PVA). This paper aims to investigate the structural, morphological, mechanical, and radiological properties of hybrid materials with the addition of PVA and without additive in the period of ageing for 28 days at room temperature. The phase composition was investigated using X-ray powder diffraction (XRPD) analysis, while morphological characteristics of these materials were examined using scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDS). Vibrational spectra of obtained samples are investigated using diffuse reflectance infrared Fourier transform (DRIFT) and Fourier transform infrared (FTIR) techniques. The hardness and compressive strength are also examined, indicating that the 1 wt% addition in geopolymeric matrix results in the best mechanical properties. Radiological measurements of investigated all geopolymer samples show decreasing activity concentrations of radionuclides for 50% compared to fly ash.
Ključne besede: geopolymer gel, inorganic binders, hybrid materials, fly ash, radiological properties, strength, open access
Objavljeno v DiRROS: 12.05.2023; Ogledov: 292; Prenosov: 135
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17. Production and characterization of lightweight aggregates from municipal solid waste incineration fly-ash through single- and double-step pelletization processAlberto Ferraro, Vilma Ducman, Francesco Colangelo, Lidija Korat, Danilo Spasiano, Ilenia Farina, 2023, izvirni znanstveni članek Povzetek: The performance of a cold-bonding pelletization process was investigated for lightweight aggregates (LWAs) production from municipal solid waste incineration (MSWI) fly-ash (FA), by including multiple waste materials in the aggregate mixture. Before pelletization, FA was pre-treated by washing with water, which led to a reduction of chloride (66.79%) and sulphate (25.30%) content. This was further confirmed by XRF and XRD analyses, which showed a reduction of chloride elements and the content of chlorine crystalline phases. The pelletization process was carried out using both single- and double-step methods. For single-step pelletization, all the mixtures contained 80% FA, combined with various compositions of cement (5, 10, and 15%) and granulated blast furnace slag (GBFS) (5, 10, and 15%). For the double-step pelletization 30% of cement and 70% of marble sludge (MS) were added to each of the previous mixtures. The apparent density of all the aggregates varied between 1.60 and 1.87 g cm 3, suggesting their suitability to be classified as LWAs. Aggregates produced from double-step pelletization showed improved characteristics, with water absorption capacity and open porosity generally lower compared to the corresponding aggregates from the single-step pelletization. The best values of compressive (crushing) strength (almost 11 MPa) were observed for double-step pelletization aggregates with initial cement: GBFS mixture of 15%:5%. Results from leaching tests showed an overall significant release of chloride and sulphate. Nevertheless, leaching from double-step pelletization aggregates was reduced by 1.73- 4.02 times for chloride and 1.58-5.67 times for sulphate, further suggesting that better performances are achievable through the addition of an aggregate second layer.
Ključne besede: MSWI fly ash, lightweight aggregate, microtomography, open access
Objavljeno v DiRROS: 03.05.2023; Ogledov: 343; Prenosov: 294
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