The role of sulfate ions in tricalcium aluminate hydration: New insights

Liu, Xin; Pan, Feng; Lyu, Chen; Ye, Shaoxiong

doi:10.1016/j.cemconres.2020.105973

Cited by 57 publications

(21 citation statements)

References 38 publications

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“…Myers et al [35] proposed that an Al-rich leached layer is formed at the partially dissolved C 3 A surface, and Ca-S ion-pair complexes are adsorbed onto this layer, decreasing the active dissolution sites and the undersaturation of calcium ions, delaying the C 3 A hydration. Recent experimental data reported in the literature [27,32,36,37] agrees with the theory that the adsorption of S and/ or Ca-S ion-pair complexes is the correct mechanism that accurately describes the retardation on C 3 A hydration.…”

Section: Effect Of Calcium Sulfate On C 3 a Hydrationsupporting

confidence: 79%

“…The authors suggest that the retardation is governed by a dissolution-controlled mechanism instead of a diffusion-controlled mechanism of the ettringite barrier hypothesis [24]. As recently showed by Liu et al [27], however, the extraction of the sulfate of the solution (by adding Ba(NO 3 ) 2 ) leads to an abrupt end of the induction period (stage II), although ettringite is still present. Also, ettringite is more abundant in C 3 A-gypsum systems, but the C 3 A-MgSO 4 systems show the highest induction period [27]; thus the ettringite formation cannot explain the delay in C 3 A hydration.…”

Section: Effect Of Calcium Sulfate On C 3 a Hydrationmentioning

confidence: 90%

“…The duration of this period of low heat release depends on the amount of calcium sulfate in the system. The higher the calcium sulfate content, the longer the duration of this period [25][26][27]. Finally, when all the added calcium sulfate is consumed, a new exothermic peak is observed due to the renewed C 3 A dissolution and the formation of monosulfate (stage III) [24,26,28].…”

Section: Effect Of Calcium Sulfate On C 3 a Hydrationmentioning

confidence: 99%

See 2 more Smart Citations

Effects of sulfates on the hydration of Portland cement – A review

Neto

Torre

Kirchheim

2021

Construction and Building Materials

120

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Section: Effect Of Calcium Sulfate On C 3 a Hydrationsupporting

confidence: 79%

Section: Effect Of Calcium Sulfate On C 3 a Hydrationmentioning

confidence: 90%

Section: Effect Of Calcium Sulfate On C 3 a Hydrationmentioning

confidence: 99%

See 1 more Smart Citation

Effects of sulfates on the hydration of Portland cement – A review

Neto

Torre

Kirchheim

2021

Construction and Building Materials

120

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“…19 Nevertheless, even small amounts of Na 2 SO 4 retards C 3 A dissolution compared to neat C 3 A-water systems. 20,21 Although ettringite is not precipitated, the formation of monosulfate has been identified in C 3 A-Na 2 SO 4 systems. 19,22…”

Section: A Hydrationmentioning

confidence: 99%

“…The addition of Na 2 SO 4 to pure C 3 A systems is considerably less effective on the retardation of hydration reactions compared to the addition of gypsum 19 . Nevertheless, even small amounts of Na 2 SO 4 retards C 3 A dissolution compared to neat C 3 A‐water systems 20,21 . Although ettringite is not precipitated, the formation of monosulfate has been identified in C 3 A‐Na 2 SO 4 systems 19,22 …”

Section: Introductionmentioning

confidence: 99%

Hydration of polyphase Ca₃SiO₅‐Ca₃Al₂O₆ in the presence of gypsum and Na₂SO₄

Joseph

Çizer

2020

J Am Ceram Soc

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Alite (Ca3SiO5: C3S*) and calcium aluminate (Ca3Al2O6: C3A) are the major phases in Portland cement, which have an essential role in the development of early age properties. The effects of gypsum content, fineness, and Na2SO4 addition on the early‐stage hydration kinetics are investigated for polyphase (co‐sintered) Ca3SiO5‐Ca3Al2O6 model systems using calorimetry, X‐ ray diffraction, thermal analysis, and solid‐state 27Al and 29Si nuclear magnetic resonance (NMR) spectroscopy. The results demonstrate that the hydration of C3A significantly affects the hydration of C3S. The C3S and C3A hydration is hindered considerably in severely over‐sulfated systems (where C3A hydration is suppressed due to a very high gypsum content) and systems with additional Na2SO4. Although there is a considerable amount of Al incorporation in the C‐S‐H phase, no clear trends with respect to gypsum content, hydration age or Na2SO4 addition are observed for the AlIV/Si ratios of the C‐S‐H phase determined from 29Si NMR. With the addition of Na2SO4, recrystallization of ettringite from the AFm phases is postponed from 1 day to 7 days. *Cement chemistry notation: C‐CaO, S‐SiO2, A‐Al2O3, trueS¯‐SO3, N‐Na2O.

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Sulfate consumption during the hydration of Alite and its influence by SCMs

Maier,

Scherb,

Thienel

2023

ce papers

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SCMs with a large specific surface area, such as calcined clays or fine limestone powder, can significantly accelerate the occurrence of the aluminate heat flow peak during the early hydration of blended cements. These systems therefore require a higher amount of sulfate. While this effect has been drawn back to the sulfate incorporation into C‐S‐H, which is formed more rapidly due to the filler effect, it has been recently shown that in systems with high amounts of metakaolin, the sulfate balance is influenced by further mechanisms. This study provides new results on the influence of aluminum‐rich and aluminum‐free SCMs on the early hydration of alite in presence of calcium sulfate. A synthesized alite was blended with 5 wt% of anhydrite and its hydration was investigated by isothermal calorimetry and in‐situ XRD at a w/b ratio of 0.5. It was shown that the formed C‐S‐H is able to take up the calcium and sulfate ions, indicated by a depletion of the solid anhydrite after approximately 20 hours. This process is significantly accelerated by incorporating 30 wt% of a fine limestone filler. The addition of metakaolin leads to an acceleration of the alite hydration compared to the reference as well, but to a significantly lower extend compared to the limestone. However, this system requires a lower degree of alite reaction to reach sulfate depletion. This indicates that in metakaolin‐rich systems, the sulfate demand is influenced by further effects. The results from in‐situ‐XRD reveal that significant ettringite formation is taking place in the metakaolin‐blended system already during the first hours of hydration. Correlations between the degree of alite hydration and the rate of sulfate depletion provide new insights into the mechanisms affecting the sulfate balance and early hydration of blended cements.

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The role of sulfate ions in tricalcium aluminate hydration: New insights

Cited by 57 publications

References 38 publications

Effects of sulfates on the hydration of Portland cement – A review

Effects of sulfates on the hydration of Portland cement – A review

Hydration of polyphase Ca₃SiO₅‐Ca₃Al₂O₆ in the presence of gypsum and Na₂SO₄

Sulfate consumption during the hydration of Alite and its influence by SCMs

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The role of sulfate ions in tricalcium aluminate hydration: New insights

Cited by 57 publications

References 38 publications

Effects of sulfates on the hydration of Portland cement – A review

Effects of sulfates on the hydration of Portland cement – A review

Hydration of polyphase Ca3SiO5‐Ca3Al2O6 in the presence of gypsum and Na2SO4

Sulfate consumption during the hydration of Alite and its influence by SCMs

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Product

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Hydration of polyphase Ca₃SiO₅‐Ca₃Al₂O₆ in the presence of gypsum and Na₂SO₄