The application of DTA and TG methods to investigate the non-crystalline hydration products of CaAl2O4 and Ca7ZrAl6O18 compounds

Szczerba, Jacek; Madej, Dominika; Śnieżek, E; Prorok, Ryszard

doi:10.1016/j.tca.2013.01.031

Cited by 20 publications

(9 citation statements)

References 19 publications

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“…It is interesting to note that major bands of Ca 7 ZrAl 6 O 18 , appearing in the 580 to 840 cm -1 region [16], have disappeared completely after hydration. The Ca 7 ZrAl 6 O 18 hydration with water gives up to the development of calcium aluminate hydrates [15][16][17][18][19]. At 50°C or above; the formation of C 3 AH 6 and gibbsite is virtually immediate [13] and it was also reported in our previous work [18].…”

Section: Resultssupporting

confidence: 73%

“…calcium zirconium aluminate, Ca 7 ZrAl 6 O 18 , that shows incongruent melting point at 1550°C, has been found by Berezhnoi and Kordyuk [14]. Ca 7 ZrAl 6 O 18 is a hydratable compound [15][16][17][18][19] that reacts with water to yield calcium aluminate hydrates (C-A-H), aluminium hydroxide and calcium zirconate, CaZrO 3 . The degree of hydration of Ca 7 ZrAl 6 O 18 is determined by water addition, temperature and time [18].…”

Section: Introductionmentioning

confidence: 92%

“…The hydrogarnet phase (C 3 AH 6 ), a crystalline form of aluminium hydroxide (Al(OH) 3 ) and CaZrO 3 , was the product from the hydration of Ca 7 ZrAl 6 O 18 at 60°C [18]. The hydrates CAH 10 , C 2 AH 8 and C 4 AH 19 , obtained at lower temperatures [16][17], are metastable phases that transform with time to more stable and denser cubic hydrogarnet C 3 AH 6 . The hydration products of Ca 7 ZrAl 6 O 18 were similar to those formed in the hydration reaction of CACs.…”

Section: Introductionmentioning

confidence: 99%

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PREPARATION OF Al₂O₃-CaAl₁₂O₁₉-ZrO₂ COMPOSITE CERAMIC MATERIAL BY THE HYDRATION AND SINTERING OF Ca₇ZrAl₆O₁₈-REACTIVE ALUMINA MIXTURE

Madej¹

2016

Ceramics - Silikaty

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Section: Resultssupporting

confidence: 73%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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PREPARATION OF Al₂O₃-CaAl₁₂O₁₉-ZrO₂ COMPOSITE CERAMIC MATERIAL BY THE HYDRATION AND SINTERING OF Ca₇ZrAl₆O₁₈-REACTIVE ALUMINA MIXTURE

Madej¹

2016

Ceramics - Silikaty

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“…In view of this state of affairs, the major thrust in development of superior cementitious systems is based on the combination of very fine particles of refractory oxides, e.g., reactive alumina micropowder, with other components tailored specifically for this purpose. In our previous works [14][15][16][17], we have investigated a hydratable compound, i.e., calcium zirconium aluminate with chemical formula of Ca 7 ZrAl 6 O 18 . It has a distinctly similar mechanism of hydration when compared to CAC, especially in terms of the C-A-H phases formed in hydrated cement paste.…”

Section: Introductionmentioning

confidence: 99%

Study of the hydration of calcium zirconium aluminate (Ca7ZrAl6O18) blended with reactive alumina by calorimetry, thermogravimetry and other methods

Madej

Szczerba

2015

J Therm Anal Calorim

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The reactivities of hydratable alumina, calcium zirconium aluminate and their binary mixtures were investigated by calorimetric method, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), differential thermal/thermogravimetric analysis (DTA-TG) and scanning electron microscope observations. The rate of heat evolution illustrates only one distinct exothermic peak in the mixtures containing calcium zirconium aluminate which corresponds the subsequent precipitation of hydrated material mainly in the form of amorphous CaO-Al 2 O 3 -H 2 O phases and crystalline C 4 AH 19 occurs simultaneously after wetting of Ca 7 ZrAl 6 O 18 grains. Nevertheless, coexistence of both unstable calcium aluminate hydrates (CAH 10 , C 2 AH 8 , C 4 AH 19 ) and thermodynamically more stable C 3 AH 6 detected by FT-IR and DTA-TG in the paste cured at 20°C may have originated in the thermally induced partial conversion reaction due to the considerable amount of heat generated by the Ca 7 ZrAl 6 O 18 hydration. It is also found that curing temperature affected the hydration products formed in the hydration products of both Ca 7-ZrAl 6 O 18 and Ca 7 ZrAl 6 O 18 /Al 2 O 3 blends. Reactive alumina influences the hydration behavior of Ca 7 ZrAl 6 O 18 facilitating the nucleation and growth of hydration products, causes characteristic changes in the microstructure of hardened blended pastes and favors recrystallization of dehydrated calcium aluminates.

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“…It is also well known that the hydraulic reactivity of these phases increases with the calcium content of the phase (CaO/Al 2 O 3 molar ratio), and therefore, C 7 A 3 Z shows higher reactivity than mineral phases of CACs. The formation and dehydration of a number of C-A-H-like phases of hydrated Ca 7 ZrAl 6 O 18 were investigated in previous works [6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Hydration, carbonation and thermal stability of hydrates in Ca7−xSrxZrAl6O18 cement

Madej

2017

J Therm Anal Calorim

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This paper studies hydration stages and phase transformation mechanism of the Sr 2? -doped calcium zirconium aluminate cement at room temperature. Features of different hydration stages of this cement paste are identified by X-ray diffraction, scanning electron microscopy, differential thermal analysis, thermogravimetric analysis, evolved gas analysis and heat evolution test. It was found that the partial isovalent substitution of Ca 2? for Sr 2? such as Ca 7-x Sr x ZrAl 6 O 18 , with x = 0.3, 0.6, 1.0, reduced the hydraulic reactivity of Ca 7 ZrAl 6 O 18 phase. The course of hydration of mixed oxides of the type 6CaOÁSrOÁ3Al 2 O 3 Á ZrO 2 documented using microcalorimetry was supported by investigations of the solid hydration products. Research showed that the hexagonal hydrates were stable at early and middle curing ages, an indication that including Sr in solid solution could effectively inhibit the conversion from both C 4 AH 13-19 and C 2 AH 8 to C 3 AH 6 and AH 3 . Calcium monocarboaluminate C 4 A CH 11 phases were also found in this system due to the carbonation process of C 4 AH 13 phase. Substitution of Ca 2? ions by Sr 2? ions in hexagonal calcium aluminate hydrates causes structural disorder and then contributes to the broadening of lines in the powder X-ray diffraction patterns of layered structures of metastable hydrates. At later curing ages, the formation of two hydrogarnet phases, one Sr-rich (C,Sr) 3 AH 6 and the other Ca-rich (C,Sr) 3 AH 6 , was proved.

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The application of DTA and TG methods to investigate the non-crystalline hydration products of CaAl2O4 and Ca7ZrAl6O18 compounds

Cited by 20 publications

References 19 publications

PREPARATION OF Al₂O₃-CaAl₁₂O₁₉-ZrO₂ COMPOSITE CERAMIC MATERIAL BY THE HYDRATION AND SINTERING OF Ca₇ZrAl₆O₁₈-REACTIVE ALUMINA MIXTURE

PREPARATION OF Al₂O₃-CaAl₁₂O₁₉-ZrO₂ COMPOSITE CERAMIC MATERIAL BY THE HYDRATION AND SINTERING OF Ca₇ZrAl₆O₁₈-REACTIVE ALUMINA MIXTURE

Study of the hydration of calcium zirconium aluminate (Ca7ZrAl6O18) blended with reactive alumina by calorimetry, thermogravimetry and other methods

Hydration, carbonation and thermal stability of hydrates in Ca7−xSrxZrAl6O18 cement

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