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Iskalni niz: "ključne besede" (hydrated cement) .

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1.
Under-calcination thermal reactivation of hydrated cement pastes and construction and demolition waste : a comparison of different commercial products
S. Castellini, Alessandro Neri, Petra Šajna, Sabina Dolenec, Andrea Balbo, Giuseppe Cruciani, 2026, izvirni znanstveni članek

Povzetek: This study explores the properties of supplementary cementitious materials (SCMs) obtained from the under-calcining thermal reactivation of construction and demolition waste fines (CDW) and of pure hydrated cement pastes (HCPs) derived from different commercial cements (CEM I, CEM II, CEM III, and CEM IV, classified according to EN 197–1). Samples were thermally treated at 350 ◦C (low-energy activation) and 600 ◦C (high-reactivity optimization) to increase pozzolanic and/or hydraulic behavior without inducing CO₂ release from calcination. Phase transformations were analyzed by X-ray Powder Diffraction with Rietveld refinement, thermal behavior by TGA/DTA, and morphological evolution by SEM, while reactivity and hydration kinetics were assessed using isothermal calorimetry. Results indicate pronounced differences in thermal response among the HCPs and CDW, governed by their specific phase assemblages and initial SCM content (limestone, slag, and pozzolans). At the selected under-calcining high-reactivity temperature (600 ◦C), γ-C₂S formation is favored. Thermal reactivation of slag-rich cement (CEM III) yielded the most reactive circular SCM, combining both high hydraulic (260 J/g - EN 196–11) and pozzolanic (329 J/g - ASTM C1897–20) performances with reduced carbon impacts.
Ključne besede: secondary scms, thermal reactivation, hydrated cement, clinker minerals
Objavljeno v DiRROS: 09.04.2026; Ogledov: 52; Prenosov: 41
.pdf Celotno besedilo (12,83 MB)
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2.
Hydration of belite–ye’elimite–ferrite cement with addition of red mud and waste concrete
Maruša Mrak, Nina Daneu, Sabina Dolenec, 2025, izvirni znanstveni članek

Povzetek: The hydration kinetics, phase assemblage, microstructure and mechanical properties of belite–ye’elimite–ferrite (BYF) cement containing different secondary raw materials (red mud and waste concrete) and cured at 5, 20 or 608C were examined. Different secondary raw materials were found to lead to changes in cement hydration. The influence of these materials on the hydration processes of belite and ferrite became more noticeable at a curing temperature of 58C, but diminished with an increase in curing temperature. The BYF cement made with red mud exhibited accelerated hydration, particularly at 58C, due to higher contents of mayenite and alkali sulfate compared with cement with natural materials and waste concrete. Red mud inhibited early ettringite formation due to the presence of aphthitalite but promoted monosulfate through accelerated ye’elimite hydration. Ferrite hydration was delayed by red mud, as alkali sulfates promote belite reactivity and calcium silicate hydrate (C-S-H) formation over stra¨tlingite. Periclase increased siliceous hydrogarnet formation at higher temperatures, supporting delayed yet stable strength development. The curing temperature impacted the morphology of the C-S-H (transitioning from a fine fibrillar-like structure to a foil-like structure) and affected the chemical composition of hydrates, resulting in a lower incorporation of iron in hydrogarnet and C-S-H at higher temperatures. Increased curing temperatures promoted aluminium uptake in calcium aluminium silicate hydrate.
Ključne besede: belite–ye'elimite–ferrite (BYF) cement, cement, cement paste, cementitious materials, hydrated cement, secondary raw materials, temperature
Objavljeno v DiRROS: 28.01.2026; Ogledov: 277; Prenosov: 266
.pdf Celotno besedilo (1,78 MB)
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