In-situ formation of layered double hydroxides (LDHs) in sodium aluminate activated slag: The role of Al-O tetrahedra

Liu, Tao; Yu, Qingliang; Brouwers, Hjh Jos

doi:10.1016/j.cemconres.2021.106697

Cited by 33 publications

(2 citation statements)

References 49 publications

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“…Peaks observed at 716, 852, 875, 1425 and 1473 cm −1 confirm the presence of calcite phases (Ylmén & Jäblid 2013;Choudhary et al, 2015;Trezza & Lavat, 2001;Liu et al, 2022) due to the asymmetric stretching of CO 3 2− . The 1363 cm −1 peak is due to the stretching vibration of CO 3 2− and means the formation of monocarboaluminate phase (Horgnies et al, 2013).…”

Section: Ft-irmentioning

confidence: 77%

Hydration Characteristics of Slag-Ca(OH)2-Al2O3 Binder in a 60 °C Curing Environment with Brine as Mixing Water

Kang,

Kim,

Park

et al. 2024

Int J Concr Struct Mater

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Recently, research results on PC-based or alkali-activated slag cement (AASC) using seawater as mixing water have been reported. Unlike seawater, reverse osmosis brine (brine) is waste discharged into the ocean from seawater desalination plants. There is a need to develop new and effective methods of disposing or utilizing brine to reduce marine pollution, protect marine ecosystems, and increase marine plant construction. However, research on cement or concrete using brine as a mixing water is very limited. Brine has almost the same composition as seawater, and the ion concentration is 2–4 times higher. Therefore, it is believed that new methods of using brine can be investigated and developed based on existing research and experimental results on seawater. The effects of brine and aluminum oxide (AO) on activated slag with calcium hydroxide (CH) were investigated for hydration and mechanical properties. 5% and 10% of CH were used, and samples using fresh water (FC) were prepared at the same time for comparison with brine. The slag sample without CH has a low initial (1 and 3d) strength of about 10 MPa for both FC and brine, but increases rapidly from 7d. Incorporation of CH was effective in improving the mechanical performance of FC and brine samples. In addition, the brine sample exhibited higher strength than the FC sample because it formed fewer C3AH6 phases that cause volume instability than the FC sample and affected the hydration promotion of slag particles. And more calcite phases were observed in the brine samples than in the FC samples. Through this study, the possibility of using brine as a building material was confirmed. In addition, the effect of chloride ion adsorption of slag mixed with AO and CH on the physical properties and mechanical performance of the hydration reaction was confirmed.

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Section: Ft-irmentioning

confidence: 77%

Hydration Characteristics of Slag-Ca(OH)2-Al2O3 Binder in a 60 °C Curing Environment with Brine as Mixing Water

Kang,

Kim,

Park

et al. 2024

Int J Concr Struct Mater

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“…Chloride binding is generally considered to be a physical or chemical process [33][34][35]. The chemical binding of chlorides has been attributed to Friedel's salt (Ca 3 Al 2 O 6 •CaCl 2 •10H 2 O) formation [36], while physical chloride binding occurs when the chloride ions are physically adsorbed on the surface of the hydration products. Such chloride binding results in reduced chloride diffusion.…”

Section: Introductionmentioning

confidence: 99%

A Review on the Effect of Metakaolin on the Chloride Binding of Concrete, Mortar, and Paste Specimens

et al. 2022

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Chloride binding is a complex phenomenon in which the chloride ions bind with hydrated Portland cement (PC) phases via physical and chemical mechanisms. However, the current utilization of clays as (Al)-rich supplementary cementitious materials (SCMs), such as metakaolin (MK), can affect the chloride-binding capacity of these concrete materials. This state-of-the-art review discusses the effect of clay-based SCMs on physical and chemical chloride binding with an emphasis on MK as a high-reactivity clay-based SCM. Furthermore, the potential mechanisms playing a role in physical and chemical binding and the MK effect on the hydrated cement products before and after exposure to chloride ions are discussed. Recent findings have portrayed competing properties of how MK limits the physical chloride-binding capacity of MK-supplemented concrete. The use of MK has been found to increase the calcium silicate hydrates (CSH) content and its aluminum to silicon (Al/Si) ratio, but to reduce the calcium to silicon (Ca/Si) ratio, which reduces the physical chloride-binding capacity of PC-clay blended cements, such as limestone calcined clay cements (LC3). By contrast, the influence of MK on the chemical chloride capacity is significant since it increases the formation of Friedel’s salt due to an increased concentration of Al during the hydration of Portland cement grains. Recent research has found an optimum aluminum to calcium (Al/Ca) ratio range, of approximately 3 to 7, for maximizing the chemical binding of chlorides. This literature review highlights the optimal Al content for maximizing chloride binding, which reveals a theoretical limit for calcined clay addition to supplementary cementitious materials and LC3 formulations. Results show that 5–25% of replacements increase bound chloride; however, with a higher percentage of replacements, fresh and hardened state properties play a more pivotal role. Lastly, the practical application of four binding isotherms is discussed with the Freundlich isotherm found to be the most accurate in predicting the correlation between free and bound chlorides. This review discusses the effects of important cement chemistry parameters, such as cation type, sulfate presence, carbonation, chloride concentration, temperature, and applied electrical fields on the chloride binding of MK-containing concretes—important for the durable formulation of LC3.

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Future Development and Challenges of New-Generation Cement-Based Nanocomposites

Ding

Wang

Han

2023

New-Generation Cement-Based Nanocomposites

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In-situ formation of layered double hydroxides (LDHs) in sodium aluminate activated slag: The role of Al-O tetrahedra

Cited by 33 publications

References 49 publications

Hydration Characteristics of Slag-Ca(OH)2-Al2O3 Binder in a 60 °C Curing Environment with Brine as Mixing Water

Hydration Characteristics of Slag-Ca(OH)2-Al2O3 Binder in a 60 °C Curing Environment with Brine as Mixing Water

A Review on the Effect of Metakaolin on the Chloride Binding of Concrete, Mortar, and Paste Specimens

Future Development and Challenges of New-Generation Cement-Based Nanocomposites

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