New understanding of early hydration of C4AF under surface vitrification

Zhang, Gaoyin; Ren, Qiang; He, Jianyong; Jiang, Shiwei; Cheng, Xiaowei; Yang, Yu; Huang, Sheng; Zhang, Chunmei; Zhou, Ming

doi:10.1016/j.powtec.2020.08.098

Cited by 23 publications

(7 citation statements)

References 17 publications

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“…It should be noted that except for the above-mentioned phases, there are several other phases existing in cement paste, such as hydrogarnet (C 3 AH 6 ), ironic hydroxide (FH 3 ), calcium alumino–ferrite hydrate (C 4 (A,F)H 13 ), etc. [ 16 , 17 ]. However, these phases are neglected in this model because the contents of these phases in cement paste are very low.…”

Section: Multiphase Model For the Thermal Conductivity Of Cement Pastementioning

confidence: 99%

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

2021

Materials

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Thermal conductivity plays a significant role in controlling thermal cracking of cement-based materials. In this study, the thermal conductivity of cement paste at an early age was measured by the hot plate method. The test results showed that the thermal conductivity of cement paste decreased with the increase of water/cement ratio and curing age. Meanwhile, a multiphase model for the thermal conductivity of cement paste was proposed and used to study the influence of saturation and curing temperature on the thermal conductivity of cement paste. To determine the parameters involved in this model, the thermal conductivity of each phase in cement paste was calculated by the molecular dynamic simulation method, and the hydration of cement was simulated by the Virtual Cement and Concrete Testing Laboratory. The inversion results showed that the relative error between experimental and simulation results lay between 1.1% and 6.5%. The thermal conductivity of paste in the saturated condition was 14.9–32.3% higher than that in the dry state. With the curing temperature increasing from 10 °C to 60 °C, the thermal conductivity of cement paste decreased by 3.9–4.9% depending on the water/cement ratio.

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Section: Multiphase Model For the Thermal Conductivity Of Cement Pastementioning

confidence: 99%

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

2021

Materials

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“…One of the current areas of cement research is lowenergy cements activated by various dopants or combinations of dopants. [10][11][12][13][14][15] The content and reactivity of C 4 AF changes significantly due to fluxes and mineralisers. A deeper understanding of the mobility of individual ions and compounds is needed to support recent knowledge of mechanisms of C 4 AF hydration.…”

Section: Introductionmentioning

confidence: 99%

“…One of the current areas of cement research is low‐energy cements activated by various dopants or combinations of dopants 10–15 . The content and reactivity of C 4 AF changes significantly due to fluxes and mineralisers.…”

Section: Introductionmentioning

confidence: 99%

Early hydration of C₄AF with silica fume and its role on katoite composition

Boháč,

Zezulová,

Krejčí Kotlánová

et al. 2024

Journal of Microscopy

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C4AF is considered the least reactive main clinker phase, but its reactivity may be affected by adding supplementary cementitious materials (SCMs). Pure C4AF was synthesised in a laboratory furnace, and the role of silica fume without gypsum on its early hydration properties was monitored. Burning was carried out in four stages to achieve 99% purity of C4AF. Heat flow development was monitored by isothermal calorimetry over 7 days of hydration at 20°C and 40°C. The role of silica fume on hydrogarnet phase katoite (Ca3Al2(SiO4)3 – x(OH)4x x = 1.5–3) formation during early hydration was studied. Rapid dissolution of C4AF, formation of metastable C‐(A,F)‐H and its conversion to C3(A, F)H6 was evidenced by isothermal calorimetry as a large exotherm. Changes in microstructure during early hydration were documented by SE micrographs, EDS point analyses, X‐ray mapping and line scans by SEM‐EDS. The phase composition was characterised by DTA‐TGA and QXRD after 7 days of hydration. The katoite diffraction pattern is similar for the reference sample and sample with silica fume, but substitution in its structure can be revealed by X‐ray microanalyses. The composition of katoite is variable due to the various extent of substitution of 4OH− by SiO44− due to silica fume.

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“…However, a high-quality bauxite requirement, high expansibility and unstable strength growth have limited the sulfoaluminate cement production and application. Based on the characteristics of C 2 S and C 4 A 3 $ minerals, the combination of C 2 S and C 4 A 3 $ minerals in a high-belite sulfoaluminate cement (HBSC) system has been proposed to overcome the respective shortcomings of belite cement and sulfoaluminate cement [9][10][11][12][13][14]. It is well known that an appropriate amount of brownmillerite can promote the sintering reaction and reduce the calcination temperature.…”

Section: Introductionmentioning

confidence: 99%

The Role of Brownmillerite in Preparation of High-Belite Sulfoaluminate Cement Clinker

Ng³

et al. 2022

Applied Sciences

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High-belite sulfoaluminate cement (HBSC) clinker containing brownmillerite was prepared using the industrial raw materials limestone, aluminum tailings, aluminum ore waste rock, and anhydrite. The effect of brownmillerite on clinker sintering and clinker minerals and the mechanical performance of HBSC was investigated using thermal analysis, petrographic analysis, and quantitative X-ray diffraction (QXRD). Results indicated that brownmillerite promoted the formation of clinker minerals and stabilized calcium sulfoaluminate (C4A3$) through the substitution of Fe3+ for Al3+ in C4A3$, which increased the actual C4A3$ content and decreased the brownmillerite content compared to that of the designed theoretical mineral composition. However, the early compressive strength of HBSC pastes decreased with the increase in brownmillerite content due to the decrease in the total amount of early-strength clinker minerals. Brownmillerite also influenced belite (C2S) structures and increased the γ-C2S content with poor hydration activity, thus inhibiting the strength development of HBSC pastes. The proper amount of brownmillerite in HBSC clinker can ensure the early strength and strength development of HBSC pastes.

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New understanding of early hydration of C4AF under surface vitrification

Cited by 23 publications

References 17 publications

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

Early hydration of C₄AF with silica fume and its role on katoite composition

The Role of Brownmillerite in Preparation of High-Belite Sulfoaluminate Cement Clinker

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New understanding of early hydration of C4AF under surface vitrification

Cited by 23 publications

References 17 publications

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

Multiphase Model for Predicting the Thermal Conductivity of Cement Paste and Its Applications

Early hydration of C4AF with silica fume and its role on katoite composition

The Role of Brownmillerite in Preparation of High-Belite Sulfoaluminate Cement Clinker

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Product

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Early hydration of C₄AF with silica fume and its role on katoite composition