Influence of foreign ions on calcium silicate hydrate under hydrothermal conditions: A review

Tian, Hongwei; Stephan, Dietmar; Lothenbach, Barbara; Lehmann, Christian

doi:10.1016/j.conbuildmat.2021.124071

Cited by 25 publications

(5 citation statements)

References 144 publications

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“…The first option is to further investigate the performance of BOFS slag based autoclaved building material products with the addition of a Si source and variable autoclave conditions. As many authors proposed before that Ca/Si ratio and the autoclave conditions are the most controlling factors on the mechanical properties [25,35,38]. The second option to produce a product based on BOF slag would be by increasing the reactivity to the BOF slag binder by chemical [26] or mechanochemical [59] activation in order to reduce the free water and increase the amount of reaction product during the autoclave process.…”

Section: Discussionmentioning

confidence: 99%

“…The phase diagrams are not applicable to our results because the system has not reached equilibrium as can be inferred from the large amounts of initial unreacted phases that still persist, as identified by QXRD. Moreover, the system at hand is not a pure CaO-SiO 2 -H 2 O system plays, which would play a significant role as well [31,32,35,38,39]. At the end, the large amount of reaction products (i.e.…”

Section: Phase Composition Before and After Autoclavingmentioning

confidence: 99%

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Reactivity of Bof Slag Under Autoclaving Conditions

et al. 2022

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Section: Discussionmentioning

confidence: 99%

Section: Phase Composition Before and After Autoclavingmentioning

confidence: 99%

Reactivity of Bof Slag Under Autoclaving Conditions

et al. 2022

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“…Nevertheless, when using waste glass powder as an additive in autoclaved building materials manufacturing, the presence of sodium ions originating from the dissolving cullet should, at least to some extent, hinder the formation of tobermorite and promote the formation of semi-crystalline or amorphous C-S-H phase. As mentioned by Tian et al [31], such an effect could positively affect the mechanical strength of the material. Therefore, a study was conducted to determine the influence of waste glass powder addition on the microstructure, phase composition, and compressive strength of autoclaved mixtures containing quicklime and ground quartz sand.…”

Section: Introductionmentioning

confidence: 88%

“…The introduction of mineral additives into the hydrating system results in the presence of the so-called "foreign ions", which affect the microstructure and phase composition of the hydrothermal reaction products [31]. In the case of waste glass powder, these ions include Na + and Al 3+ .…”

Section: Introductionmentioning

confidence: 99%

Influence of Waste Glass Powder Addition on the Microstructure and Mechanical Properties of Autoclaved Building Materials

et al. 2022

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Lime quartz samples in which ground quartz sand was gradually substituted with waste glass powder (GP) were obtained under hydrothermal conditions to determine the influence of GP addition on the microstructure (observed by SEM), phase composition (analyzed by XRD), and compressive strength of autoclaved building materials. An additional series containing analytical grade NaOH and no GP was formed to evaluate the effect of sodium ions on tobermorite formation and its impact on the mechanical properties of the samples. GP addition hindered the formation of tobermorite during autoclaving. Instead, a higher amount of an amorphous and semi-crystalline C–S–H phase formed, leading to the densification of the composite matrix. Nevertheless, tobermorite-like structures were found during both XRD and SEM analyses, proving that the presence of small amounts of Al3+ ions allowed, to an extent, for the stabilization of the phase despite the high sodium content. The compressive strength values indicate that the presence of alkali in the system and the resulting formation of additional portions of C–S–H have a beneficial influence on the mechanical properties of autoclaved composites. However, the effect fades with increasing glass powder content which, together with a slight expansion of the samples, suggests that at high sand substitution levels, an alkali–silica reaction takes place.

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“…Compositional variations can be obtained during hydrothermal synthesis by the partial isomorphic replacement of SiO 4 4− for other tetrahedral oxyanions (e.g., AlO 4 5− , FeO 4 5− , PO 4 3− , SO 4 2− ), by the limited substitution of structural Ca 2+ for other divalent cations (e.g., Mg 2+ ), and by the complete replacement of structural Ca 2+ with trivalent lanthanides (e.g., Eu 3+ , Ce 3+ , Sm 3+ , Tb 3+ ) [43][44][45][46][47][48][49]. Extensive ion-exchange of the labile inter-layer cations for a wide range of mono-, di-, and trivalent species (e.g., Na + , K + , Cs + , Ag + , Sr 2+ , Zn 2+ , Cr 3+ inter alia) can be achieved within a few hours and is generally accompanied by a change in basal spacing [9,27,32,35,36,50].…”

Section: Introductionmentioning

confidence: 99%

Calcium Silicate Hydrate Cation-Exchanger from Paper Recycling Ash and Waste Container Glass

Hurt

Coleman

et al. 2022

Ceramics

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Synthetic 11 Å tobermorite (Ca5Si6O16(OH)2.4H2O) and its Al-substituted analogue are layer-lattice ion-exchangers with potential applications in nuclear and hazardous wastewater treatment. The present study reports the facile one-pot hydrothermal synthesis of an Al-tobermorite-rich cation-exchanger from a combination of paper recycling ash, post-consumer container glass, and lime, with compositional ratios of [Ca]/[Si + Al] = 0.81 and [Al]/[Si + Al] = 0.18. The reaction products were characterized by powder X-ray diffraction analysis, 29Si magic angle spinning nuclear magnetic resonance spectroscopy, and scanning electron microscopy. Hydrothermal processing in 4 M NaOH(aq) at 100 °C for 7 days yielded an Al-tobermorite-rich product that also contained katoite (Ca3Al2SiO12H8), portlandite (Ca(OH)2), calcite (CaCO3), and amorphous silicate gel. The hydrothermal product was found to have a Cs+ cation exchange capacity of 59 ± 4 meq 100 g−1 and selective Cs+ distribution coefficients (Kd) of 574 ± 13 and 658 ± 34 cm3 g−1 from solutions with molar ratios [Cs+]:[Na+] and [Cs+]:[Ca2+] of 1:100. In a batch sorption study at 20 °C, the uptakes of Pb2+, Cd2+, and Cs+ were determined to be 1.78 ± 0.04, 0.65 ± 0.06, and 0.36 ± 0.03 mmol g−1, respectively. The kinetics of Pb2+, Cd2+, and Cs+ removal were described by the pseudo-second-order rate model, which gave respective rate constants (k2) of 0.010, 0.027, and 1.635 g mmol−1 min−1, and corresponding correlation coefficients (R2) of 0.997, 0.996, and 0.999. The metal ion sorption properties of the tobermorite-rich product compared favorably with those of other waste-derived tobermorites reported in the literature. Potential strategies to improve the yield, crystallinity, and sorption characteristics of the product are discussed.

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Influence of foreign ions on calcium silicate hydrate under hydrothermal conditions: A review

Cited by 25 publications

References 144 publications

Reactivity of Bof Slag Under Autoclaving Conditions

Reactivity of Bof Slag Under Autoclaving Conditions

Influence of Waste Glass Powder Addition on the Microstructure and Mechanical Properties of Autoclaved Building Materials

Calcium Silicate Hydrate Cation-Exchanger from Paper Recycling Ash and Waste Container Glass

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