Details
Originalsprache | Englisch |
---|---|
Aufsatznummer | 107258 |
Fachzeitschrift | Cement and concrete research |
Jahrgang | 173 |
Frühes Online-Datum | 17 Juli 2023 |
Publikationsstatus | Veröffentlicht - Nov. 2023 |
Abstract
The crystallization of calcium hydroxide (Ca(OH)2, CH, portlandite) is a key process during the early stages of cement hydration. In the present work, we have revisited the formation of this mineral through nucleation and growth from supersaturated aqueous solutions, in the light of the currently emerging picture of multistage “non-classical” crystallization. To that end, we developed a titration-based assay, in which stock solutions of both relevant ions are added simultaneously into a reservoir, where supersaturation increases slowly at constant stoichiometry until nucleation occurs. This procedure allows both pre- and early post-nucleation phenomena to be analyzed quantitatively. Complementarily, the early stages of portlandite mineralization were probed by various advanced characterization techniques, including cryo-transmission electron microscopy (cryo-TEM), in-situ small-angle X-ray scattering (SAXS), pair distribution function (PDF) analysis of high-energy X-ray scattering (HEXS) data, and analytical ultracentrifugation (AUC). The experimental data show that the formation of calcium hydroxide starts with the association of ions into complexes and clusters, which subsequently coalesce to form amorphous nanoparticles – much like what has been observed in the case of calcium carbonate and other prominent minerals. Subsequently, these particles aggregate and build networks, which eventually transform into hexagonal Ca(OH)2 crystals. The presence of a soluble polycarboxylate – as a known inhibitor of portlandite crystallization – does not change the main characteristics of this multistep nucleation pathway, but it proved capable of significantly extending the lifetime of the amorphous intermediate phase and thus delaying the transition to the final crystalline phase. Our observations confirm the notion that “non-classical” crystallization is a much more common phenomenon than initially believed – and that, for minerals forming in aqueous environments, it may actually be the rule rather than the exception.
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- Ingenieurwesen (insg.)
- Bauwesen
- Werkstoffwissenschaften (insg.)
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in: Cement and concrete research, Jahrgang 173, 107258, 11.2023.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - New insights into the nucleation of portlandite and the effects of polymeric additives
AU - Madeja, Benjamin
AU - Gebauer, Denis
AU - Marsiske, Maximilian R.
AU - Ott, Andreas
AU - Rückel, Markus
AU - Rosenberg, Rose
AU - Baken, Annet
AU - Stawski, Tomasz M.
AU - Fernandez-Martinez, Alejandro
AU - Van Driessche, Alexander E.S.
AU - Cölfen, Helmut
AU - Kellermeier, Matthias
N1 - Funding Information: The authors thank Dr. Michael Laumann and the Electron Microscopy Centre at the University of Konstanz for support during SEM studies, Elisabeth Wagner (BASF SE) for conducting TOC analyses, as well as Ralf Sander and Dr. Tobias Umbach (BASF SE) for carrying out nanoindentation experiments. Access to beamlines ID02 and ID15a at ESRF for SAXS and HEXS experiments through grant numbers ES 526 and ES 608, respectively, and support by ESRF experts is highly appreciated. AESVD and AFM acknowledge funding from the Spanish Ministerio de Ciencia y Innovacion through the Grant TED2021-130860B-I00 .
PY - 2023/11
Y1 - 2023/11
N2 - The crystallization of calcium hydroxide (Ca(OH)2, CH, portlandite) is a key process during the early stages of cement hydration. In the present work, we have revisited the formation of this mineral through nucleation and growth from supersaturated aqueous solutions, in the light of the currently emerging picture of multistage “non-classical” crystallization. To that end, we developed a titration-based assay, in which stock solutions of both relevant ions are added simultaneously into a reservoir, where supersaturation increases slowly at constant stoichiometry until nucleation occurs. This procedure allows both pre- and early post-nucleation phenomena to be analyzed quantitatively. Complementarily, the early stages of portlandite mineralization were probed by various advanced characterization techniques, including cryo-transmission electron microscopy (cryo-TEM), in-situ small-angle X-ray scattering (SAXS), pair distribution function (PDF) analysis of high-energy X-ray scattering (HEXS) data, and analytical ultracentrifugation (AUC). The experimental data show that the formation of calcium hydroxide starts with the association of ions into complexes and clusters, which subsequently coalesce to form amorphous nanoparticles – much like what has been observed in the case of calcium carbonate and other prominent minerals. Subsequently, these particles aggregate and build networks, which eventually transform into hexagonal Ca(OH)2 crystals. The presence of a soluble polycarboxylate – as a known inhibitor of portlandite crystallization – does not change the main characteristics of this multistep nucleation pathway, but it proved capable of significantly extending the lifetime of the amorphous intermediate phase and thus delaying the transition to the final crystalline phase. Our observations confirm the notion that “non-classical” crystallization is a much more common phenomenon than initially believed – and that, for minerals forming in aqueous environments, it may actually be the rule rather than the exception.
AB - The crystallization of calcium hydroxide (Ca(OH)2, CH, portlandite) is a key process during the early stages of cement hydration. In the present work, we have revisited the formation of this mineral through nucleation and growth from supersaturated aqueous solutions, in the light of the currently emerging picture of multistage “non-classical” crystallization. To that end, we developed a titration-based assay, in which stock solutions of both relevant ions are added simultaneously into a reservoir, where supersaturation increases slowly at constant stoichiometry until nucleation occurs. This procedure allows both pre- and early post-nucleation phenomena to be analyzed quantitatively. Complementarily, the early stages of portlandite mineralization were probed by various advanced characterization techniques, including cryo-transmission electron microscopy (cryo-TEM), in-situ small-angle X-ray scattering (SAXS), pair distribution function (PDF) analysis of high-energy X-ray scattering (HEXS) data, and analytical ultracentrifugation (AUC). The experimental data show that the formation of calcium hydroxide starts with the association of ions into complexes and clusters, which subsequently coalesce to form amorphous nanoparticles – much like what has been observed in the case of calcium carbonate and other prominent minerals. Subsequently, these particles aggregate and build networks, which eventually transform into hexagonal Ca(OH)2 crystals. The presence of a soluble polycarboxylate – as a known inhibitor of portlandite crystallization – does not change the main characteristics of this multistep nucleation pathway, but it proved capable of significantly extending the lifetime of the amorphous intermediate phase and thus delaying the transition to the final crystalline phase. Our observations confirm the notion that “non-classical” crystallization is a much more common phenomenon than initially believed – and that, for minerals forming in aqueous environments, it may actually be the rule rather than the exception.
KW - Amorphous precursors
KW - Analytical ultracentrifugation
KW - Calcium hydroxide
KW - Cryo-TEM
KW - Mineralization
KW - Non-classical crystallization
KW - Nucleation
KW - Pair distribution function analysis
KW - Polymer-controlled crystallization
KW - Potentiometric titration
KW - Pre-nucleation clusters
KW - SAXS
UR - http://www.scopus.com/inward/record.url?scp=85165032108&partnerID=8YFLogxK
U2 - 10.1016/j.cemconres.2023.107258
DO - 10.1016/j.cemconres.2023.107258
M3 - Article
AN - SCOPUS:85165032108
VL - 173
JO - Cement and concrete research
JF - Cement and concrete research
SN - 0008-8846
M1 - 107258
ER -