Hydrophobic Properties of Calcium-Silicate Hydrates Doped with Rare-Earth Elements

Burek, Katja; Krause, Felix; Schwotzer, Matthias; Nefedov, Alexei; Süssmuth, Julia; Haubitz, Toni; Kumke, Michael U.; Thissen, Peter

doi:10.1021/acssuschemeng.8b03244

Cited by 15 publications

(18 citation statements)

References 24 publications

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“…This is in good agreement with the observations by Burek et al. . The luminescence of the other two Eu(III) species is characterized by their long luminescence decay times (τ 2 and τ 3 ) indicating a significantly decreased quenching rate due to a reduced number of OH‐oscillators in the coordination sphere.…”

Section: Discussionsupporting

confidence: 92%

“…Here, complementary analytical techniques are needed to characterize the influence of admixtures. Recently, europium‐doped C−S−H phases were investigated using Eu(III) luminescence to probe structural properties . Using time‐resolved laser fluorescence spectroscopy (TRLFS), structural information on the C−S−H phases can be obtained regardless of their crystallinity.…”

Section: Introductionmentioning

confidence: 99%

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Lanthanide Luminescence Revealing the Phase Composition in Hydrating Cementitious Systems

Burek

Dengler²,

Emmerling

et al. 2019

ChemistryOpen

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The hydration process of Portland cement in a cementitious system is crucial for development of the high‐quality cement‐based construction material. Complementary experiments of X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM) and time‐resolved laser fluorescence spectroscopy (TRLFS) using europium (Eu(III)) as an optical probe are used to analyse the hydration process of two cement systems in the absence and presence of different organic admixtures. We show that different analysed admixtures and the used sulphate carriers in each cement system have a significant influence on the hydration process, namely on the time‐dependence in the formation of different hydrate phases of cement. Moreover, the effect of a particular admixture is related to the type of sulphate carrier used. The quantitative information on the amounts of the crystalline cement paste components is accessible via XRD analysis. Distinctly different morphologies of ettringite and calcium−silicate−hydrates (C−S−H) determined by SEM allow visual conclusions about formation of these phases at particular ageing times. The TRLFS data provides information about the admixture influence on the course of the silicate reaction. The dip in the dependence of the luminescence decay times on the hydration time indicates the change in the structure of C−S−H in the early hydration period. Complementary information from XRD, SEM and TRLFS provides detailed information on distinct periods of the cement hydration process.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Lanthanide Luminescence Revealing the Phase Composition in Hydrating Cementitious Systems

Burek

Dengler²,

Emmerling

et al. 2019

ChemistryOpen

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“…ESEM images of ultrathin CSH phases grown on silicon wafers at different temperatures. Note that similar images have been published in ref .…”

Section: Resultssupporting

confidence: 58%

“…Sorbents in dynamic systems are amine-based (NH 4 + ), and they capture CO 2 from ambient air when dry and release it when wet (the so-called moisture swing) . In this context, a key result for mineral science has been recently published: contrary to metal-oxide systems, exchange of metals without degrading the silicate structure was demonstrated, the so-called metal–metal exchange reaction . This finding opens the door to future design of silicates with incorporated ions for specific applications.…”

Section: Introductionmentioning

confidence: 99%

Chemical Properties of Metal-Silicates Rendered by Metal Exchange Reaction

Longo

Königer

Nefedov

et al. 2019

ACS Sustainable Chem. Eng.

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Calcium-silicates and calcium-silicate-hydrates (CS and CSH) are well-known as the most important building material, cement. Both CS and CSH phases react fast with CO2 from the atmosphere. Due to the porosity of cement and concrete, such reaction goes deep into the material, producing phase transformations, crack formation and propagation. The aim of this work is 2-fold. In the first part, we compare the reaction of CO2 with CSH phases and with magnesium-silicate-hydrates (MSH). Surprisingly, MSH did not show any contamination of carbonates in the infrared spectra. While the reaction of CO2 with CSH has been well studied and explained, there is currently no explanation about the resilience of MSH to the interaction with CO2. For the first time, the atomistic details of the reaction of CO2 with MgSiO3 are shown, and the chemical resistance of MgSiO3 against CO2 and other relevant chemicals for corrosion of cement and concrete is explained. Second, we demonstrate that Mg and other metals can undergo an exchange in situ process in CS and CSH phases. Depending on the type of metal exchanged, a completely new platform for rendering the properties of cement and concrete surfaces against corrosion is developed.

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“…Some previous studies focused on the sorption behavior of trivalent actinides and lanthanides on C-S-H gel 6,20,22,23 . Häußler et al .…”

Section: Resultsmentioning

confidence: 99%

Cm(III) retention by calcium silicate hydrate (C-S-H) gel and secondary alteration phases in carbonate solutions with high ionic strength: A site-selective TRLFS study

Wolter

Schmeide

Huittinen

et al. 2019

Sci Rep

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We studied the Cm(III) retention by calcium silicate hydrate (C-S-H), portlandite (Ca(OH)2) and their alteration products calcite, vaterite, and aragonite in high ionic strength carbonate-containing solutions representing specific formation waters. For this, we synthesized C-S-H gels with calcium to silicon (C/S) ratios of 1.0 and 2.0 in the absence and presence of Cm(III), resulting in Cm(III)-free and Cm(III) doped C-S-H gel, respectively. For phase identification purposes we applied X-ray diffraction (XRD) while for the identification of the Cm(III)/C-S-H binding mode we applied site-selective time-resolved laser-induced luminescence spectroscopy (TRLFS). The stability of Cm(III) doped phases under repository-relevant conditions was evaluated by studying the time-dependent release of Cm(III) from the Cm(III) doped C-S-H gel into leaching solutions containing 0.02 M NaHCO3 or 2.5 M NaCl/0.02 M NaHCO3 over 60 d. Speciation changes of Cm(III) due to leaching were followed with TRLFS while C-S-H structure alterations and secondary phase formation were monitored with XRD. From the results it could be concluded that Cm(III) is not mobilized by aqueous carbonate but either remains incorporated in the C-S-H structure and portlandite or becomes partially re-immobilized into secondary CaCO3 phases. The presence of NaCl led to an accelerated conversion of metastable secondary CaCO3 phases into calcite.

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Hydrophobic Properties of Calcium-Silicate Hydrates Doped with Rare-Earth Elements

Cited by 15 publications

References 24 publications

Lanthanide Luminescence Revealing the Phase Composition in Hydrating Cementitious Systems

Lanthanide Luminescence Revealing the Phase Composition in Hydrating Cementitious Systems

Chemical Properties of Metal-Silicates Rendered by Metal Exchange Reaction

Cm(III) retention by calcium silicate hydrate (C-S-H) gel and secondary alteration phases in carbonate solutions with high ionic strength: A site-selective TRLFS study

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