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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: 164; Prenosov: 145
Celotno besedilo (1,78 MB)
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Povzetek: This study focuses on the kinetics of hydration, phase assemblage, microstructure and mechanical properties after various hydration times of two different BCSA cements at 5, 20, 40 and 60 ◦C and compares experimental data with thermodynamic modelling. Different curing temperatures change the type of hydrates and their amounts. Ye’elimite and gypsum in belite-ye’elimite-ferrite cements are almost fully reacted after 24 h of hydration at 20, 40 and 60 ◦C, while not at 5 ◦C. The hydration of belite is slower than the one of ye’elimite, but reaches a high degree of hydration after 150 days which is increasing with temperature. Less ettringite is present at elevated temperatures due to its increasing solubility, while more monosulfate is observed. Furthermore, with increasing temperature siliceous hydrogarnet forms at the expenses of strätlingite as well as more C S H is found as more belite reacts resulting in higher compressive strength. Dense and homogenous microstructure is observed at 5 ◦C, while it is more heterogeneous at higher temperatures. The presence of more ye’elimite resulted in higher ettringite and str¨atlingite formation and a higher compressive strength, while more belite yields more C S H in the hydrates and lower compressive strength.
Ključne besede: belite-ye’elimite-ferrite cement, temperature, hydration, thermodynamic modelling
Objavljeno v DiRROS: 11.12.2023; Ogledov: 1364; Prenosov: 1121
Celotno besedilo (9,96 MB)
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