301. Influence of alkalis on the phase development of belite-sulfoaluminate clinkersBarbara Čeplak, Katarina Šter, Maruša Mrak, Luka Škrlep, Mirijam Vrabec, Sabina Dolenec, 2022, original scientific article Abstract: This paper presents a study on the influence of different amounts of alkalis (K2O and Na2O) on clinker phase formation, microstructure, phase composition and reactivity of belite-sulfoaluminate cement clinker. Using X-ray powder diffraction and scanning electron microscopy with energy dispersive spectrometry, it was found that the amount of C2S and C4AF increases with the incorporation of alkalis, while the amount of C4A3Ś and CŚ decreases. In addition to the major phases, the samples with alkalis also consist of minor phases such as C3A (tricalcium aluminate), KŚ (arcanite), and KC2Ś3 (Ca-langbeinite). The major ions in the major phases were substituted by alkali cations and some other ions (Ca2+, Al3+, Fe3+, S2-, S6+, Si4+). The alkalis also affect the microstructure of the clinker, e.g., the shape of the grains. Consequently, isothermal calorimetry was used to detect differences in hydration kinetics. The clinker with 2 wt. % K2O content was the most reactive, while the sample with 0.5 wt. % Na content was the least reactive. The latter was primarily influenced by the content of the main and minor phases of the clinker.
Keywords: BCSA clinker, microstrcuture, reactivity, alkalis, open access
Published in DiRROS: 06.12.2022; Views: 534; Downloads: 268
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302. Comparison of the corrosion properties of CoCrMo dental alloys in artificial salivaTadeja Kosec, Mirjam Bajt Leban, Matej Kurnik, Igor Kopač, 2021, original scientific article Abstract: CoCrMo alloys are known for their biocompatible properties, which, together with their favorable mechanical properties, mean they can be efficiently used in dentistry. With the development of selective laser melting for the fabrication of 3D-printed ob - jects, interest in the corrosion properties of this alloy has risen in the field of prosthodontics. In the study, CoCrMoW dental al - loys were studied in artificial saliva at body temperature, i.e., 37 °C. Different forms of CoCrMoW alloy were selected: a refer - ence sample, i.e., original material as received from the supplier, a cast sample acquired from an ordinary procedure in a dental laboratory, and two 3D-printed samples made from CoCrMoW powder using the selective laser melting (SLM) method. Electro - chemical, spectroscopic and hardness measurements were conducted. It was shown that the reference and cast samples have similar microstructural and electrochemical properties, while the electrochemical properties of the 3D-printed samples differ, most probably due to the effect of the higher micro porosity and chemical composition of the alloys.
Keywords: CoCrMo dentalne zlitine, umetna slina, aditivne tehnologije, precizijsko ulivanje, korozija
Published in DiRROS: 02.12.2022; Views: 257; Downloads: 106
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303. Building of the Al-Containing secondary raw materials registry for the production of low CO2 mineral binders in South-Eastern European regionGorazd Žibret, Klemen Teran, Lea Žibret, Katarina Šter, Sabina Dolenec, 2021, original scientific article Abstract: The bottleneck in the process for increasing production of low CO2 mineral binders, based on BCSA (belite sulfoaluminate) clinkers, is the availability of Al-rich raw materials. For that purpose, a new registry of Al-containing secondary mineral residues (industrial and mine waste) has been developed and is presented in this paper. The methodology of creating the registry consists of three main steps: Gathering ideas, consolidation of ideas, and implementation. In order to achieve this, the following methodology was adopted: Analysis of similar registries by potential end-users and seeking potential solutions and tools to be used, and conducting 3 rounds of stakeholder consultations via workshops in order to determine crucial parameters and features the registry needs to contain. The key discussion points were about which data the registry needs to contain, who shall be the potential users, and what are the stakeholderʼs expectations from the registryʼs portal. Potential individual registry variables were identified as being relevant/irrelevant or available/unavailable, and potential solutions for the registrys sustainability were explored. Each Al-rich waste/residue data entry is divided into 10 slots, describing legal status, location, quantities, chemical (REE included), mineralogical, physical and radiological properties, life-cycle assessment, additional data, and data relevancy. The registry will act as a matchmaking tool between producers/holders of Al-rich secondary raw materials and potential producers of cement clinkers.
Keywords: cement, belite sulfoaluminate clinker, waste, by--product, deležniki
Published in DiRROS: 10.06.2022; Views: 540; Downloads: 324
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304. The valorisation of selected quarry and mine waste for sustainable cement production within the concept of circular economyEmilija Fidanchevski, Katarina Šter, Maruša Mrak, Ljiljana Kljajević, Gorazd Žibret, Klemen Teran, Bojan Poletanovic, Monika Fidanchevska, Sabina Dolenec, Ildikó Merta, 2022, original scientific article Abstract: The cement industry could potentially consume large amounts of solid industrial waste in order to improve its sustainability. The suitability of selected quarry and mine waste as secondary raw materials (SRM) was examined for the sustainable production of cement following the concept of a circular economy. The chemical, mineralogical, and radiological characterization of SRM was conducted in this study. Its potential use in low-carbon and low-energy belite-sulfoaluminate cement was investigated by incorporating the examined SRM into cement clinker. Various characterization methods were used to characterize the cement, including X-ray powder diffraction (XRD), thermal analysis (DTA/TG), and isothermal calorimetry. Depending on the chemical composition of the waste, lower or higher amounts were allowed to be incorporated into the raw clinker mixture for a targeted clinker phase composition. Among the samples, differences were observed in the phase composition of synthesized clinkers, which slightly influenced the reactivity of the cement but did not significantly change the compressive strength of the final product.
Keywords: mineralne surovine, rudarski odpadki, rudniki, kamnolomi, cement, klinker, krožno gospodarstvo, BCSA clinker, cement, circular economy, clinker, mine wastes, quarry waste
Published in DiRROS: 10.06.2022; Views: 607; Downloads: 320
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