1. Temperature performance and rutting prediction of steel slag asphalt mixturesHongwen Du, Qinghao Han, Yunhao Wu, Linhua Ma, Minda Ren, 2025, original scientific article Keywords: road engineering, performance prediction, steel slag–rubber powder-modified asphalt mixture, optimization algorithms
Published in DiRROS: 03.10.2025; Views: 419; Downloads: 183
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2. Fast transformation of PbTe using a multiphase mixture of precursors : first insightsHugo Rojas-Chávez, Nina Daneu, J. Manuel Juárez-García, 2025, original scientific article Abstract: For the first time, a mixture of PbTe and Pb- and Te-oxides coated with carbon, under electron beam irradiation (EBI), was transformed into quantum dots, nanocrystals, nanoparticles and grains of PbTe with a sintered appearance. A small portion of non-stoichiometric phases was also obtained. By selecting conditions that favor the instantaneous transformation, the Gibbs free energy barrier is lowered for obtaining different PbTe structures. The driving force associated with the high-energy milling requires 4 h of processing time to reach a complete transformation, while a high-energy source kinetically affects precursor surfaces to cause an abrupt global chemical transformation instantly. Importantly, the size of the PbTe structures increases as they approach the irradiation point, implying a growth process that is affected by the local temperature reached during the EBI. Imaging after the EBI process revealed morphological variations in PbTe, which can be attractive for use in thermoelectric materials. The results of this study provide the first insights into electron-beam-induced reactions using a multiphase mixture of precursors. Therefore, it is believed that this proposal can also be applied to obtain other binary semiconductor structures, even ternary ones.
Keywords: semiconductor, multiphase mixture of precursors, rate of transformation
Published in DiRROS: 15.07.2025; Views: 458; Downloads: 311
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3. Experimental and numerical study of Taylor bubble in counter-current turbulent flowIztok Tiselj, Jan Kren, Blaž Mikuž, Raksmy Nop, Alan Burlot, Grégoire Hamrit, 2025, original scientific article Abstract: The stagnant Taylor bubble in vertical isothermal turbulent counter-current flow was analyzed using 2D shadowgraphy experiments and two distinct high-fidelity numerical simulations. One simulation employed the geometrical VOF interface tracking method within the OpenFOAM code, while the other utilized the explicit front tracking method of the TrioCFD code. Interface recognition algorithms were applied to the photographs and compared with the results of 3D simulations performed with LES and pseudo-DNS accuracy in OpenFOAM and TrioCFD, respectively. The measured Taylor bubbles exhibited an asymmetric bullet-train shape and a specific speed, which were compared with the predictions of both numerical approaches. Reproducing the experiment proved challenging for both otherwise well-established methods frequently used in interface tracking simulations of two-phase flows. Grid resolution and subgrid turbulent models, known for their success in single-phase turbulence, were less accurate near the water–air interface. Additional experimental parameters compared with simulations were related to the dynamics of tiny disturbance waves with amplitudes ranging from 10 to 100 µm along the interface of the Taylor bubbles. The speed and spectra of the surface disturbance waves were reproduced numerically with moderate success despite detailed grid refinement in the relevant region of the computational domain.
Keywords: gas–liquid mixture flows, slug flow, Taylor bubble, shadowgraphy, front tracking
Published in DiRROS: 10.04.2025; Views: 1069; Downloads: 362
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4. Evaluation of the performance of clay-based bricks with the addition of co-combustion ashLea Žibret, Ivana Carević, Nina Štirmer, Ivan Koloda, Mojca Vrčon, Miha Kragelj, Vilma Ducman, 2025, published scientific conference contribution Abstract: The gradual replacement of coal by local renewable resources leads to an increased production of co-combustion ashes (CC). Their disposal can be limited by their use in the construction sector, where they can partially replace primary raw materials. This study evaluates the incorporation of selected Slovenian CC ash into clay-based fired bricks within the EU AshCycle project. The tests included the measurement of water absorption, porosity, density, weight loss, shrinkage, flexural and compressive strength, and freeze-thaw resistance. Two types of clay were used to compare the influence of the selected ash on the performance of the fired samples. Replacing clay mixtures with 10 wt% CC ash reduced the compressive strength of the fired bricks but it still reached the required 10 MPa as specified in EN 772-1 (2015). The addition of CC ash to fired bricks requires careful planning of the raw mixes, taking into account various parameters that may affect the properties of the products.
Keywords: fired clay bricks, waste ashes, raw mixture, ceramic-technological tests, freeze-thaw resistance
Published in DiRROS: 07.04.2025; Views: 848; Downloads: 510
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5. Dataset for the conference paper Evaluation of the performance of clay-based bricks with the addition of co-combustion ashLea Žibret, Ivana Carević, Nina Štirmer, Ivan Koloda, Mojca Vrčon, Miha Kragelj, Vilma Ducman, 2025, complete scientific database of research data Abstract: The dataset supports the data in the tables and figures in the conference article Evaluation of the performance of clay-based bricks with the addition of co-combustion ash (doi: https://doi.org/10.18690/um.fkkt.1.2025.15). It contains the particle size distribution (PSD) measurements, the original data of the XRD analyses, the original results of the XRF measurements, the original results of the water absorption and shrinkage of the samples, fired in gradient kiln as well as the original results of the ceramic-technological tests of bricks after drying and firing at 950 °C.
Keywords: fired clay bricks, waste ashes, raw mixture, ceramic-technological tests, freeze-thaw resistance
Published in DiRROS: 03.12.2024; Views: 936; Downloads: 485
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7. Volumetric view on asphalt mixtureMarjan Tušar, Mojca Ravnikar Turk, Lidija Ržek, 2023, published scientific conference contribution Abstract: An asphalt layer consists of stone aggregates, binder and air voids. The content of air voids (Vmin and Vmax), the voids filled with bitumen (VFBmin and VFBmax), the content of air voids in stone aggregates (VMAmin and VMAmax) and volume content of bitumen (VBmin) should be determined for each type of asphalt mixture. The volumetric properties of asphalt layer listed above are important parameters for assessing the properties of asphalt and are usually first presented in the requirements for produced asphalt mixtures and built in asphalt layers. Visualization of volumetric properties is important for understanding the composition of the produced asphalt mixture. The most appropriate is a triangular representation of the volumetric requirements for three main components of asphalt layer (stone, bitumen and air).
Keywords: volumetric representation, asphalt mixture, void content, voids in aggregate
Published in DiRROS: 22.02.2024; Views: 1356; Downloads: 649
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8. A triangular representation of the volumetric properties of asphalt mixturesMarjan Tušar, Mojca Ravnikar Turk, Lidija Ržek, 2022, original scientific article Keywords: triangular representation, asphalt mixture, volumetric properties, void content, bitumen content, voids in aggregate
Published in DiRROS: 10.03.2022; Views: 1740; Downloads: 1078
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