Tobermorite Synthesis Under Hydrothermal Conditions

Galvánková, Lucie; Másilko, Jiří; Solný, Tomáš; Štěpánková, Eva

doi:10.1016/j.proeng.2016.07.394

Cited by 77 publications

(47 citation statements)

References 28 publications

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“…In order to obtain one single phase, some researchers used the responding oxides to prepare tobermorite and hydrogarnet. For example, tobermorite was synthesized from lime and quartz or lime and fumed silica powder under the hydrothermal condition with the designed Ca/Si molar ratio (0.83) according to the ideal composition of tobermorite (Ca 5 Si 6 O 16 (OH) 2 •4H 2 O) [13,33,44,50]. Hydrogarnet was synthesized through silica gel, calcium hydroxide, and γ-alumina [51].…”

Section: Crystalmentioning

confidence: 99%

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

2019

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To elucidate the physicochemical properties of the artificial silicate composite material, K-feldspar and lime were reacted in mild hydrothermal conditions (different reaction temperatures and various K-feldspar/lime ratios). Formed phases were investigated using various techniques, such as X-ray powder diffraction, the Rietveld method, scanning electron microscopy (SEM), and inductively coupled plasma-optical emission spectrometry. The analysis revealed that tobermorite, grossular (hydrogarnet), alpha-dicalcium silicate hydrate (α-C2SH), amorphous calcium silicate hydrate, potassium carbonate, bütschliite, calcite, and calcium hydroxide formed with various conditions. Both the temperature and the Ca/Si molar ratio in the starting material greatly affected the formation of phases, especially the generation of tobermorite and α-C2SH. The substitution of H4O4 ↔ SiO4 proceeded with the increase of the Ca/Si molar ratio rather than the reaction temperature and the reaction time. More hydrogen was incorporated in hydrogarnet through the substitution of H4O4 ↔ SiO4 with the increase of the Ca/Si molar ratio in the starting material. Due to the properties of tobermorite as a cation exchanger and its potential applications in hazardous waste disposal, experimental parameters should be optimized to obtain better performance of the artificial silicate composite material from K-feldspar and lime hydrothermal reaction. The dissolution mechanism of K-feldspar was also discussed.

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Section: Crystalmentioning

confidence: 99%

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

2019

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“…Therefore, α-C2SH is likely to form in calcium-rich environments, at incipient reaction, whereas tobermorite would form later, as a phase evolving from metastable calcium-silicate-hydrates 51,52 . Tobermorite has been observed for initial bulk molar composition at Ca/Si=0.8-1.0 and processing times in the order of days [53][54][55] 24,55 . This latter type was confirmed in this study (Figure 3b, Figure 3e).…”

Section: Hydrothermal Chemistry Considerationsmentioning

confidence: 99%

“…Furthermore, Al-substituted tobermorites show a higher selectivity for Cs, and possibly other heavy metals, which may be particularly useful to remediate contaminated soils 54,57,58 . The charge of such mineral phases is envisaged to further benefit soils.…”

Section: Soil Science Considerationsmentioning

confidence: 99%

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Potassium fertilizer via hydrothermal alteration of K-feldspar ore

2017

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“…A tobermorite crystal growing in natural conditions is highly crystalline and forms in an alkaline environment under hydrothermal condition as fibers or plates . Three tobermorite phases have been distinguished on the basis of their basal spacing: 14 Å tobermorite (Ca 5 Si 6 O 16 (OH) 2 ·7H 2 O), which is the most hydrous one; 11 Å tobermorite (Ca 5 Si 6 O 16 (OH) 2 ·5H 2 O); and water‐free 9 Å tobermorite (Ca 5 Si 6 O 16 (OH) 2 ) . But the most important type of tobermorite is 11 Å, major phase of AAC.…”

Section: Introductionmentioning

confidence: 99%

Innovations in the crystalline structure forming and its effects on the mechanical performance of AAC

Kavas

Tan

Tiriç³

et al. 2018

ce papers

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This study is mainly focused on the crystalline structure and mechanical properties of autoclaved aerated concrete (AAC) without losing any other specific performances such as low bulk density and good thermal insulation capacity. For this purpose, colemanite (C) was added in a proportion of 0.3, 1, 3, 10, 15, 20, and 30% by weight to standard G2/350 receipt during raw material mixing process. After mixing, mud prepared with the suitable amount of starting materials with water was slipping into the laboratory scale metal moulds. Moulded samples were cured under the condition of 55% humidity and 50-55 • C for 4 h and sent to autoclave line. Cut-sized samples were left under the 12 bars pressure for 5 h. Density (Kg/m 3 ), lambda values (W/mK), and compressive strength (MPa) of the samples have been measured. Selected samples that have the highest mechanical strength were examined mineralogically (XRD) and microstructurally by scanning electron mircoscope (SEM). The results show that boron atoms from calcined colemanite (CC) diffused into the tobermorite crystalline structure and remained as an interstitial atom in this structure. Thus, mechanical performance of samples with CC increased more than double time according to the standard G2/350 recipe. K E Y W O R D S AAC, colemanite, crystalline structure, diffusion, mechanic performance

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Tobermorite Synthesis Under Hydrothermal Conditions

Cited by 77 publications

References 28 publications

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

Study of K-Feldspar and Lime Hydrothermal Reaction: Phase and Mechanism with Reaction Temperature and Increasing Ca/Si Ratio

Potassium fertilizer via hydrothermal alteration of K-feldspar ore

Innovations in the crystalline structure forming and its effects on the mechanical performance of AAC

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