Structure, bonding and morphology of hydrothermally synthesised xonotlite

Black, L.; Garbev, Krassimir; Stumm, A.

doi:10.1179/10.1179/174367608x353638

Cited by 5 publications

(5 citation statements)

References 13 publications

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“…Many analytical methods are used to investigate the structural features of crystalline or nanocrystalline C(-A)-S-H phases, such as X-ray diffraction (XRD) [ 23 , 24 ], Fourier transform infrared spectroscopy (FTIR) [ 25 ], 29 Si magic angle spinning nuclear magnetic resonance spectroscopy ( 29 Si MAS NMR) [ 26 , 27 , 28 ], or X-ray photoelectron spectroscopy (XPS) [ 24 , 29 ]. However, numbers of the corresponding studies are performed on the C-S-H phases synthesized from stoichiometric starting compositions or crystalline phases formed in nature.…”

Section: Introductionmentioning

confidence: 99%

Phase Composition of Silica Fume—Portland Cement Systems Formed under Hydrothermal Curing Evaluated by FTIR, XRD, and TGA

et al. 2021

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Two substitution levels of Portland cement by silica fume (SF; 30 and 50 mass%) and three hydrothermal treatment regimes (0.5, 1.2, and 2 MPa and 165, 195, and 220 °C for 7 days, respectively) were selected for the investigation of high-temperature phase formation. A combination of thermogravimetric, X-ray diffraction, and Fourier transform infrared analyses in the mid-IR region was used to overcome the shortcomings of individual techniques for the identification of these complex systems. Changes in molecular water amounts, the polymerization degree of silicate chains, or their decomposition due to transformations and crystallization of phases at hydrothermal conditions were observed and discussed concerning composition. Contrary to the calciochondrite, hydrogrossular phases, α-C2SH, and jaffeite detected in the systems without SF, a decrease in CaO/SiO2 ratio resulted in the formation of stable tobermorite in the case of 30 mass% SF, whilst calcium hydrogen silicate, gyrolite, and cowlesite were identified as more thermally stable phases in the samples with 50 mass% SF.

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Section: Introductionmentioning

confidence: 99%

Phase Composition of Silica Fume—Portland Cement Systems Formed under Hydrothermal Curing Evaluated by FTIR, XRD, and TGA

et al. 2021

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“…What concerns the morphology of crystals, there was an increase in crystal size with increasing temperature, but this led to some crystal damage. Longer hydrothermal treatment, however, leads to more perfect crystal morphologies [12]. The synthesis of xonotlite also depends on state of used lime component.…”

Section: Introduction *mentioning

confidence: 99%

Influence of Hydrothermal Synthesis Condition on Xonotlite Crystal Morphology

Spudulis

Šavareika

Špokauskas

2013

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This investigation was made to examine how the conditions of hydrothermal synthesis influence the crystal structure of xonotlite and its morphology. For synthesis we used amorphous silica fume and SiO₂/CaO molar ratio equal to 1.0, water-solids ratio W/S = 10 and W/S = 15. The samples were cured hydrothermally in the rotation autoclave with mixing rod for 2 and 4 hours at 200°C. The products were characterized by X-ray diffraction, differential thermal analysis, thermogravimetry, SEM, atomic force microscopy and mercury intrusion porosimetry. The low W/S ratio and mixing intensity had a decisive effect on processes of formation of xonotlite. During the 4-hour synthesis at W/S = 15, well formed xonotlite fiber of 0.2 mm diameter was obtained. Under the same conditions, but at W/S = 10, the obtained xonotlite was poorly formed, with fiber of 0.07 mm diameter. The mercury intrusion porosimetry method was used to examine and compare the surface of synthesized xonotlite. In the case of well formed xonotlite, the surface equals to 8.027 m²/g and that of poorly formed xonotlite 22.328 m²/g. The investigation of pressed xonotlite powder by XRD shows the rise in diffraction peak intensity (0.700; 0.324) nm and the drop in diffraction peak intensity (0.308; 0.184) nm. With tobermorite, there is a rise in diffraction peak intensity (1.13; 0.542) nm.

DOI: http://dx.doi.org/10.5755/j01.ms.19.2.4437

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“…A significant increase of curing temperature can result in the phase breakdown followed by recrystallisation of other phases with weaker properties at microscopic scale (or at crystal scale). In the work reported by Black et al [15]. concerning xonotlite and was not general to hydrothermally formed phases, an increasing synthesis temperature led to larger crystals, but the crystals also appeared to have split along their length.…”

Section: Resultsmentioning

confidence: 92%

Untitled

2019

CERJ

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The mechanical properties of sand-lime bricks produced by autoclaving under different conditions and incorporation of granulated slag have been investigated previously. In this study, the relationship is established between the structure, the phases formed and the strength. Based lime and granulated slag a new binder is developed. This is cured at saturated vapour pressures of 1.0 and 1.8MPa. The results showed a decrease in compressive strength due to the substitution. The microstructure analysis showed that reaction products consist mainly of 11Å tobermorite and xonotlite. Also, when increasing the autoclave temperature, it results in an increase in xonotlite relative to tobermorite. The X-ray diffractions of these phases are very low hardly visible, they are masked by the presence of quartz. Their intensities increase with the presence of slag.

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Structure, bonding and morphology of hydrothermally synthesised xonotlite

Cited by 5 publications

References 13 publications

Phase Composition of Silica Fume—Portland Cement Systems Formed under Hydrothermal Curing Evaluated by FTIR, XRD, and TGA

Phase Composition of Silica Fume—Portland Cement Systems Formed under Hydrothermal Curing Evaluated by FTIR, XRD, and TGA

Influence of Hydrothermal Synthesis Condition on Xonotlite Crystal Morphology

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