Phase assemblage in ettringite-forming cement pastes: A X-ray diffraction and thermal analysis characterization

Qoku, Elsa; Bier, Thomas; Westphal, Torsten

doi:10.1016/j.jobe.2017.05.005

Cited by 61 publications

(26 citation statements)

References 43 publications

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“…e rst major dehydration peaks in the DTG curves (Figure 8(b)) were for the C-S-H gel and ettringite. Based on a previous report [32], the peak section from 50°C to 200°C was not only for the C-S-H gels but also for the ettringite phase. erefore, it was di cult to nd an obvious distinction between the dehydration temperatures for the C-S-H gels and ettringite phase.…”

Section: Tg-dtg Analysismentioning

confidence: 93%

Preparation of Portland Cement with Gold Ore Tailings

Wang

Yao

Zhu

et al. 2019

Advances in Materials Science and Engineering

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e disposal of gold ore tailings (GTs) has been a very difficult problem for a long time. us, this study explored a new approach to the management of GTs by preparing Portland cement. Physical properties, reaction mechanisms, and hydration product types of cement prepared with GTs (C-GTs) and ordinary Portland cement (C-SS) were compared. X-ray diffraction (XRD), thermogravimetric (TG), and scanning electron microscope energy-dispersive spectroscopy (SEM-EDS) analysis techniques were used to study the mineralogical phases of the clinker and raw materials, hydration product types, and microtopography. e consistency, setting time, flexural strength and compressive strength values of the cement samples (C-GTs and C-SS), and burnability of the raw materials were also studied. e burnability analysis indicated that GTs provided a higher reactivity. e XRD results showed that the clinker phases of the C-GTs were C 3 S, C 2 S, C 3 A, and C 4 AF. e XRD, TG, and SEM-EDS results showed that the hydration products were flaky calcium hydroxide, rod-shaped ettringite, and granular C-S-H gels. Its compressive strength and flexural strength were, respectively, 30.4 MPa and 6.1 MPa at the curing age of 3 days and 59.1 MPa and 9.8 MPa at the curing age of 28 days, which were slightly higher than those of the C-SS. Furthermore, the results showed that the consistency, initial setting time, and final setting time for the two kinds of cement were similar, which further suggested that GTs could be used to prepare Portland cement.

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Section: Tg-dtg Analysismentioning

confidence: 93%

Preparation of Portland Cement with Gold Ore Tailings

Wang

Yao

Zhu

et al. 2019

Advances in Materials Science and Engineering

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“…In terms of phase types of crystalline hydration products, the hydration products of the unmodified straw fiber DX1 In terms of phase content of crystalline hydrates, according to the phase identification and analysis by Jade software and combined with the relevant literature [54][55][56][57][58][59], the diffraction peak area of each phase and the relative content of total amount of hydration products of SFCC are shown in Table 6. It can be seen from Table 6 that from the relative content of total hydration products, the relative content of total hydration products mixed with the unmodified fiber DX1 is the lowest and the relative content of total hydration products mixed with modified straw fiber DX2-DX6 is higher than that of DX1.…”

Section: Effect Of Modification Methods On Hydrates Of Sfccmentioning

confidence: 99%

Effect of Straw Fiber Modification Methods on Compatibility between Straw Fibers and Cement‐Based Materials

Jiang

Cui

et al. 2020

Advances in Civil Engineering

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To improve the utilization of crop straws as a resource and the compatibility between straw fibers and cement-based materials, the hydration of modified straw fiber cement-based composite (SFCC) was studied. e structural characteristic of SFCC was investigated by FTIR, SEM, and XRD. e results show that the setting time of several modified straw fiber SFCC pastes was shorter than that of the unmodified straw fiber SFCC paste, and the best method of fiber modification to improve the setting time of the SFCC paste is Na 2 O·nSiO 2 treatment. e recommended fiber modification method for improving the compatibility between straw fibers and cement-based materials is alkali modification, followed by pure acrylic emulsion modification and Na 2 O·nSiO 2 modification. To improve the strength of SFCC, the straw fiber should be modified by alkali, followed by pure acrylic emulsion and Na 2 O·nSiO 2 modification and the method of water modification is also recommended. e phase types and relative contents of crystalline hydration products mixed with the modified straw fiber SFCC are significantly higher than those of the unmodified fiber SFCC. e fiber treatment method that was most helpful to increase the structural density of hydrates of SFCC was alkali treatment and pure acrylic emulsion treatment, followed by Na 2 O·nSiO 2 treatment.

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“…, and portlandite (Ca(OH) 2 ), respectively. During heating from 80 to 120 • C, 26 mol of water will be removed from AFt [18]. The amount of AFt in the specimen can be calculated by Equation (2).…”

Section: Mineral Composition Examinationmentioning

confidence: 99%

Deterioration Process of Concrete Exposed to Internal Sulfate Attack

et al. 2020

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Damage to concrete structures with gypsum-contaminated aggregate occurs frequently. Aggregates in much of the southern part of China are contaminated with gypsum. Therefore, in this study, the effects of using different quantities of gypsum-contaminated aggregate on the expansion and compressive strength of concrete were investigated over a period of one year. Two groups of concrete were designed with the gypsum-contaminated aggregate containing different parts of fine and coarse aggregate, respectively. The SO3 contents were 0%, 0.5%, 1%, 1.5%, 3%, 5%, and 7% by weight of aggregate. X-ray diffraction (XRD), thermogravimetry (TG), and differential scanning calorimetry (DSC) were used to analyze the change in mineral composition over time. The microstructure was also studied by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that significant expansion and great loss in compressive strength did not occur in concrete if the content of SO3 lay below 1.5% and 3% in fine and coarse aggregates, respectively. The concentration of sulfate ions in concrete was not enough to form new a phase of gypsum. During the process of internal sulfate attack, the content of gypsum decreased and the content of ettringite increased. Ettringite was the main reason for the expansion damage of concrete. Additionally, the fracture mode of internal sulfate attack on concrete was the crack extension from gypsum to paste; finally, the aggregate separated from the paste.

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Phase assemblage in ettringite-forming cement pastes: A X-ray diffraction and thermal analysis characterization

Cited by 61 publications

References 43 publications

Preparation of Portland Cement with Gold Ore Tailings

Preparation of Portland Cement with Gold Ore Tailings

Effect of Straw Fiber Modification Methods on Compatibility between Straw Fibers and Cement‐Based Materials

Deterioration Process of Concrete Exposed to Internal Sulfate Attack

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