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State of the art on low-clinker cements and future roadmap
No full textThe expansion of infrastructural and construction work raises the demand for cement-based binders. The two factors that have the biggest effects on sustainability are cement usage and concrete production. This review study's goal is to provide a pathway for the sustainability assessment of binders' production in terms of cost, carbon emissions, and energy demand. The performances of geopolymer concrete (GC) and traditional cement-based concrete (NC) are juxtaposed with those of limestone calcined clay cement (LC3) concrete. The significance of LC3 in lowering CO2 emissions in the cement sector is evaluated, along with the raw materials utilized in its production and the material's end characteristics including hydration routes and mineralogy. The economic viability and social acceptability of LC3 in the building sector, as well as any possible effects on local communities, are also evaluated in the study. According to the assessment, the energy demand and CO2 emission of NC, GC, and LC3 concrete can be significantly impacted by the materials chosen for the concrete mix, especially if the alternative raw materials or waste streams are utilized. The primary source of energy consumption and carbon emission in GPC is the alkaline medium, while in NC is OPC production. The LC3 system is a more economical, energy-efficient, and carbon-efficient material than GC and NC concrete. A discussion of future prospects and research needs, including suggestions for further production innovation and LC3 production scaling is conducted. According to the review paper's conclusions, LC3 offers a sustainable and economically feasible substitute for conventional cement materials, with the potential to significantly lower the cement industry's carbon footprint
Correlation between Microstructure and Hardness of a Flash Butt-Welded Rail Joint
No full textIn this paper, the results analysis of microstructure and hardness examination of pearlite rail steel type 260 and its welded joint are presented. The relationship
between the microstructure and the local hardness in different zones of the Flash Butt Welding (FBW) weld was examined, and the correlation was interpreted in terms of
the quality of the examined microstructure. The main microstructural variations in the FBW weld occur within the Heat Affected Zone (HAZ). The local decrease in hardness
in the zone of intercritical HAZ is caused by spheroidization of cementite. For this reason, the measured hardness values changed when advancing from the centreline of
the weld towards the base metal. When moving slightly from the centreline of the weld to the maximum value across the weld in the area 1-2 mm away from the centre of
the weld, the hardness value increased sharply. At the visible extent of HAZ, where the pearlite is partially spheroidized, the hardness decreased to a minimum value. Moving
away from the visible part of the ZUT, the hardness gradually increased, returning to the value of the hardness of the base metal. The purpose of this paper is to present the
relationship between microstructure and hardness on the longitudinal section of a flash butt-welded rail joint and to indicate their inter relationship. It has been confirmed that
the altered microstructure in the welded joint of the rail leads to a change in hardness in areas of reduced hardness
Experimental analysis of thermal conductivity of fly ash from “Kostolac” thermal power plant
No full textFly ash, a by-product of coal combustion, represents both an environmental challenge and a potential resource for sustainable construction. This paper presents the results of laboratory investigations of the thermal conductivity of fly ash and an assessment of its possible application in geotechnical systems. The results show that moisture content has a dominant influence on thermal properties, while the effects of bulk density and curing are less significant. The measured values indicate that fly ash exhibits stable and consistent thermal behavior, suitable for engineered fills or soil-ash mixtures
Selection of the optimal underground mining method using the PROMETHEE method: A case study of "Okrugli Brijeg", Tomislavgrad, Bosnia and Herzegovina
No full textSelection of the optimal mining method is a critical engineering decision that must account for a
variety of factors such as safety, ore exploitation potential, depletion rates, production costs, and profitability.
This study focuses on finding the optimal mining method for the bauxite mine "Okrugli Brijeg"Tomislavgrad,
considering the specific working conditions. A comparative analysis of four different potential methods that
could be used in mentioned mine was carried out. In evaluating these methods, the PROMETHEE technique
was applied, which allowed for a multi-criteria decision-making approach. This method facilitated the ranking
of the excavation alternatives, helping to identify the best selection based on the set of key factors. The analysis
also involved reviewing the justification for continuing with the current excavation method and whether
switching to another approach could potentially offer improvements in one or more of the critical areas
mentioned
Nutritional and contaminant profiles of refined table salt and its alternatives
No full textGrowing health concerns regarding excessive sodium intake and the processing of refined table salt have sparked increased interest in alternative salt products. While these are often perceived as healthier, their elemental and contaminant profiles are not fully understood. This study analyzed four types of commercially available salts: refined table salt, Himalayan salt, sea salt, and potassium-enriched salt. Each group included several samples from different suppliers, encompassing all major brands currently available on the market. Concentrations of macroelements, trace elements, radionuclides, and microplastic particles were assessed. Elemental composition was determined using ICP-OES, radionuclides were analyzed by gamma spectrometry, and microplastics were quantified by visual microscopy following hydrogen peroxide digestion. Refined table salt exhibited minimal contamination but offered limited nutritional value. Himalayan salt had slightly elevated levels of certain trace elements and naturally occurring radionuclides compared to refined salts, but all remained within the safety thresholds. Potassium-enriched salts provide health benefits, but showed increased levels of 40K contributing to a higher radiological risk. Sea salts were highly contaminated with microplastics and contained lower levels of both beneficial and toxic elements. Ultimately, Himalayan salt emerged as the most favorable option, offering a balanced mineral profile with minimal contaminant risk
Metalurška šljaka kao mogući aditiv u alitnim cementima
No full textSmanjenje troškova deponovanja otpadnih proizvoda iz industrijskih procesa kroz njihovu ponovnu upotrebu je predmet mnogih istraživanja. Ovakav pristup je veoma važan jer odlaganje otpadnih proizvoda ima negativan uticaj na životnu sredinu, čak i ako se radi o neopasnom otpadu. Osnovna ideja ovog istraživanja je bila da se pripremi nova vrsta maltera sa dodatkom bakarne šljake koja je dobijena kao nusproizvod Topionice bakra u Boru. Izvršena je detaljna karakterizacija uzorka bakarne šljake koja je podrazumevala određivanje sadržaja vlage i gustine uzorka, granulometrijskog sastava polaznog uzorka, meljivost, granulometrijski i mineraloški sastav mikroniziranog uzorka. Nakon mikronizacije uzorka bakarne šljake izvršena je priprema novih vrsta maltera sa zamenskim masenim udelima od 10, 20, 36 i 55 mas % u alitnim cementima. Rezultati geomehaničkih ispitivanja su pokazali da sistem sa masenim udelom bakarne šljake od 10 mas% ostvaruje čvrstoće na pritisak od 39,2 MPa nakon 7 dana hidratacije dok čist alitni cement u istom periodu hidratacije ima čvrstoću na pritisak od 38,6 MPa. Prisustvo minerala etringita je potvrdilo da je u procesu hidratacije došlo do formiranja stabilne strukture usled postepenog očvršćavanja cementne paste
Numerical assessment of shear force redistribution in beam-slab systems due to incompatible kinematic assumptions
No full textIn finite element analysis, shear force in a Timoshenko beam can be grossly underestimated if the beam is coupled with a thin (Kirchhoff) plate in the finite element mesh. Although common knowledge in the field of structural mechanics, this error is rarely warned about and frequently overlooked in practice, since most of the commercial software packages do not prevent the user from combining finite elements with incompatible kinematic assumptions. Moreover, thin plates are commonly offered as the default option, so the mistake needs to be actively avoided. This article demonstrates and investigates the issue through numerical and analytical parametric studies. Theoretical background is provided to explain the observed behavior. The error is confirmed to be strongly dependent on model geometry and mesh refinement. As a solution, it is recommended to always combine beam and plate theories with mutually compatible kinematic assumptions: Euler-Bernoulli with Kirchhoff and Timoshenko with Mindlin
Investigation of the impact of the magnetic separation technique on the recovery of non-ferrous metals from Pb-Zn smelter slag
No full textThis study offers new approach to the non-ferrous metals’ concentration from Pb-Zn slag using a magnetic separation. This technology is more ecological than conventional processes, therefore it may have a substantial influence on the progress of metallurgical slag beneficiation techniques. Physicochemical and mineralogical investigations indicated that Pb-Zn slag is an inhomogeneous with considerable Pb, Zn, Cu, and Ag amounts. Experiments showed that the separated magnetic fraction includes unequal quantities of arsenic, preventing the output from being commercial. Arsenic content was 0.3-32%. Optical and scanning electron microscopy with EDS determined if arsenic can be liberated or easily leached from the resulting material. It was discovered that arsenic is mainly fused with iron-bearing minerals, which are predominantly trapped within amorphous alumino-silicates or intergrowths of alloy grains and glassy phases. This indicates that the produced iron concentrate is viable as a commercial product and in compliance with circularity principles and Green Agenda
Discover Sustainability Journal
No full textUređivanje međunarodnog naučnog časopisa; Uređivanje tematskih monografija - na godišnjem nivou
https://link.springer.com/journal/43621/editors
https://portal.issn.org/resource/ISSN-L/2662-998