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Abstract: Belite-sulfoaluminate (BCSA) cements are low-carbon mineral binders, which require low energy consumption and allow the incorporation of various secondary raw materials in the clinker raw meal. In this study two types of unprocessed steel slags, coming from stainless steel production, were incorporated in the BCSA clinkers. The clinker phase composition, clinker reactivity, and the compressive strength of the cement were studied to evaluate the possible use of the slag in BCSA clinkers. The cement clinkers were synthesized by using natural raw materials, white titanogypsum, mill scale, as well as two different steel slags: (i) EAF S slag, which is a by-product of melting the recycled steel scrap in an electric arc furnace, and (ii) la dle slag as a by-product of the processes of secondary metallurgy, in various quantities. Raw mixtures with two different targeted phase compositions varying in belite, calcium sulfoaluminate and ferrite phases were sintered at 1250 °C. Clinker phases were determined by Rietveld quantitative phase analysis, while their distribution, morphology and incorporation of foreign ions in the phases were studied by SEM/EDS analysis. The clinker reactivity was determined by isothermal calorimetry. BCSA cements were prepared by adding titanogypsum. The compressive strength of the cement pastes was determined after 7 days of hydration. The presence of a predicted major clinker phases was confirmed by Rietveld analysis, however periclase was also detected. Microscopy revealed subhedral grains of belite and euhedral grains of calcium sulfoaluminate phases, while ferrite occurred as an interstitial phase. The results showed differences in the microstructure and reactivity of the clinker and cement, which can be attributed to varying amounts of ettringite due to different slag types
Keywords: belite-sulfoaluminate cement, cement clinker, steel slags, clinker microstructure, cement reactivity
Published in DiRROS: 19.01.2024; Views: 161; Downloads: 74
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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: 516; Downloads: 315
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