31. Report of RILEM TC 267-TRM phase 3 : validation of the R3 reactivity test across a wide range of materialsDiana Londono-Zuluaga, Sabina Dolenec, Maruša Mrak, 2022, izvirni znanstveni članek Povzetek: RILEM TC 267 TRM– “Tests for Reactivity of Supplementary Cementitious Materials” recommends the Rapid Reliable Relevant (R3) test as a method for determining the chemical reactivity of supplementary cementitious materials (SCMs) in Portland cement blends. In this paper, the R3 test was applied to 52 materials from a wide range of conventional and alternative SCMs with the aim to validate such test. An excellent correlation was found between the cumulative heat release and the bound water determined following the R3 test method. Comparison of the R3 test results to mortar compressive strength development showed that all conventional SCMs (e.g. blast furnace slag and fly ashes) followed the same trend, with the notable exception of very reactive calcined kaolinitic clays. It is discussed, through an in-depth statistical regression analysis of the R3 reactivity test results and the 28 days relative compressive strengths, how reactivity threshold values for classification of the chemical reactivity of SCMs could be proposed based on the R3 test results.
Ključne besede: supplementary cementitious materials, reactivity test, heat release, bound water, compressive strength
Objavljeno v DiRROS: 26.04.2023; Ogledov: 254; Prenosov: 146
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32. Report of RILEM TC 267-TRM phase 2 : optimization and testing of the robustness of the R3 reactivity tests for supplementary cementitious materialsFrançois Avet, Sabina Dolenec, Maruša Mrak, 2022, izvirni znanstveni članek Povzetek: The results of phase 1 of an interlaboratory test, coordinated by the RILEM TC 267-TRM “Tests for Reactivity of Supplementary Cementitious Materials” showed that the R3 (rapid, relevant, reliable) test method, by measurement of heat release or bound water, provided the most reliable and relevant determination of the chemical reactivity of supplementary cementitious materials (SCMs), compared to other test methods. The phase 2 work, described in this paper aimed to improve the robustness of the test procedure and to develop precision statements for the consolidated test procedure. The effect of the pre-mixing and mixing conditions, and the impact of the mix design on the test method robustness were assessed and fixed for optimal conditions to carry out the R3 heat release test. The effect of the drying step was evaluated to define the R3 bound water test procedure in more detail. Finally, the robustness of the consolidated final test methods was determined by an interlaboratory study to define the precision statements.
Ključne besede: supplementary cementitious materials, reactivity test, bound water
Objavljeno v DiRROS: 26.04.2023; Ogledov: 317; Prenosov: 128
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33. Influence of alkalis on the phase development of belite-sulfoaluminate clinkersBarbara Čeplak, Katarina Šter, Maruša Mrak, Luka Škrlep, Mirijam Vrabec, Sabina Dolenec, 2022, izvirni znanstveni članek Povzetek: 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.
Ključne besede: BCSA clinker, microstrcuture, reactivity, alkalis, open access
Objavljeno v DiRROS: 06.12.2022; Ogledov: 541; Prenosov: 272
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34. 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, izvirni znanstveni članek Povzetek: 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.
Ključne besede: cement, belite sulfoaluminate clinker, waste, by--product, deležniki
Objavljeno v DiRROS: 10.06.2022; Ogledov: 552; Prenosov: 327
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35. 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, izvirni znanstveni članek Povzetek: 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.
Ključne besede: mineralne surovine, rudarski odpadki, rudniki, kamnolomi, cement, klinker, krožno gospodarstvo, BCSA clinker, cement, circular economy, clinker, mine wastes, quarry waste
Objavljeno v DiRROS: 10.06.2022; Ogledov: 621; Prenosov: 325
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