Study on the preparation and sulfate resistance of Portland cement clinker with the high Fe/Al ratio of ferrite phase

Shao, Yulin; Lu, Xiaolei; Li, Qiang; Dong, Yiran; Zhang, Lina; Jiang, Congcong; Du, Peijun; Cheng, Xin

doi:10.1016/j.cemconcomp.2022.104699

Cited by 18 publications

(8 citation statements)

References 53 publications

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“…The Fe-rich ettringite in the hardened cement paste, formed from the high Fe/Al ferrite phase, exhibited no transformation to AFm after 7 and 28 days, demonstrating high stability of Fe-rich ettringite under sulfate attacks. 20 The interplay between Fe content, the less expansive feature of iron-containing ettringite, and its influence on ettringite stability emerges as a complex and critical aspect in understanding the sulfate resistance of cementitious materials. Wan et al explored the impact of Fe content on AFt formation at various temperatures using chemical synthesis.…”

Section: Introductionmentioning

confidence: 99%

Microscopic effect of iron dosage on the stability of Fe‐doped ettringite

Bouibes,

Laanaiya,

Lacarrière

2024

J Am Ceram Soc.

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One significant aspect that affects the performance of high‐ferrite cement is the incorporation of iron (Fe) atoms and its stabilization into the cement phases. However, the influence of Fe doping on the stability of key phases, particularly on the ettringite, remains largely unexplored requiring deeper insights into the fundamental mechanisms. The present study explored the stability of Fe‐doped AFt structure based on density functional theory calculations at different Fe dosage. The obtained results showed that the stability of AFt structure decreases by increasing Fe dosage, which is in good agreement with the previous experimental observations. The incorporation of Fe into ettringite induced a series of changes in AFt structural and electronic properties. Bond order analysis underscored stronger covalent Fe–O bonds compared to Al–O, further emphasizing changes in the material's bonding network. Notably, density of states (DOS) analysis highlights the emergence of new occupied states near the Fermi level, primarily contributed by Fe and O atoms. This increased DOS, coupled with higher electron mobility, correlates with a reduction in material stability, as observed through shifts in bonding interactions and alterations in the bonding network. These findings point toward a complex interplay of factors, including altered bonding characteristics, increased electron mobility, and changes in the electronic structure, contributing to the observed instability of Fe‐doped ettringite.

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Section: Introductionmentioning

confidence: 99%

Microscopic effect of iron dosage on the stability of Fe‐doped ettringite

Bouibes,

Laanaiya,

Lacarrière

2024

J Am Ceram Soc.

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“…Recent work reported that the formation of an Al-rich leached surface and the adsorption of the Ca 2+ -SO 4 2− ion complex on this leach surface could explain the critical C 3 A dissolution rate limiting effect. 21 The adsorption of sulfate on a Ca-rich surface was proposed for the retardation mechanism, and a higher pH value decreased the SO 4 2− adsorption rate 16 where pH affected the enrichment of Ca and Al on the mineral surfaces. 24 New evidence showed that Na 2 SO 4 did not retard C 3 A hydration, and it was believed that Ca 2+ played a vital role in retardation where the chemical adsorption of Ca 2+ facilitated the negatively charged SO 4 2− adsorption on the surface, reducing the available reactive sites by a block effect.…”

Section: Introductionmentioning

confidence: 99%

“…Fe-rich Portland cement has been applied to reduce carbon emission and enhance sulfate resistance, which was composed of less C 3 A (0-2 wt.%) and higher C 4 AF (18-22 wt.%) than ordinary Portland cement (4-10 wt.% and 8-15 wt.% respectively), and it has attracted much attention in cleaner cement production. [2][3][4][5][6][7][8][9] C 4 AF and C 3 A determine the setting, workability, early and late strength, and durability of cement, and calcium sulfate (CaSO 4 ) is added to retard the hydration of C 4 AF and C 3 A, which avoids flash set and optimizes the strength development by avoiding a superimposed reaction between C 3 S and C 4 AF/C 3 A. 10 CaSO 4 also accelerated C 3 S hydration and enhanced the strength development.…”

Section: Introductionmentioning

confidence: 99%

“…Decreasing the consumption of CaCO 3 in cement can effectively reduce carbon emissions, for example, manufacturing cement with higher dicalcium silicate (C 2 S) and tetracalcium aluminoferrite (C 4 AF) contents as well as lower tricalcium silicate (C 3 S) and tricalcium aluminate (C 3 A) contents. Fe‐rich Portland cement has been applied to reduce carbon emission and enhance sulfate resistance, which was composed of less C 3 A (0–2 wt.%) and higher C 4 AF (18–22 wt.%) than ordinary Portland cement (4–10 wt.% and 8–15 wt.% respectively), and it has attracted much attention in cleaner cement production 2–9 . C 4 AF and C 3 A determine the setting, workability, early and late strength, and durability of cement, and calcium sulfate (CaSO 4 ) is added to retard the hydration of C 4 AF and C 3 A, which avoids flash set and optimizes the strength development by avoiding a superimposed reaction between C 3 S and C 4 AF/C 3 A 10 .…”

Section: Introductionmentioning

confidence: 99%

“…22 Ye et al 23 confirmed that sulfate inhibited the evolution of etch pits and the dissolution of C 3 A by in situ observation. Recent work reported that the formation of an Al-rich leached surface and the adsorption of the Ca 2+ -SO 4 2− ion complex on this leach surface could explain the critical C 3 A dissolution rate limiting effect. 21 The adsorption of sulfate on a Ca-rich surface was proposed for the retardation mechanism, and a higher pH value decreased the SO 4 2− adsorption rate 16 where pH affected the enrichment of Ca and Al on the mineral surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the adsorption of calcium sulfate on tetracalcium aluminoferrite and tricalcium aluminate surfaces

2023

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Calcium sulfate (CaSO4), an essential retarder in cement, retards the hydration of tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF) phases. However, its retarding mechanism remains unclear. This paper focused on the adsorption of CaSO4f on C4AF and C3A surfaces based on isothermal calorimetry, the measurement of the ionic concentrations in a diluted system, and density functional theory to enhance the understanding of the retardation mechanism. The results showed that the retarding effect of CaSO4 on C4AF was stronger than that on C3A due to the slower CaSO4 consumption rate, lower driving force for CaSO4 adsorption, and surface coverage of Fe(OH)3 gel. The adsorption of CaSO4 hindered Ca dissolution more markedly on C4AF than C3A, which was pronounced on Fe‐free C4AF surfaces. The adsorption of CaSO4 weakened the affinity of water on C4AF and C3A surfaces, lowering the driving force for H2O adsorption. The adsorption of H2O and CaSO4 promoted the dissolution of Al on the [AlO6] octahedral surface of C4AF, which may be responsible for the maintenance of a higher Al concentration in the solution. Based on the above results, the adsorption of CaSO4 on initial C4AF and C3A hydration was explained.

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