Authors:	Maslyk, Marcel Gäb, Tobias Matveeva, Galina Opitz, Phil Mondeshki, Mihail Krysiak, Yasar Kolb, Ute Tremel, Wolfgang
Title:	Multistep crystallization pathways in the ambient-temperature synthesis of a new alkali-activated binder
Online publication date:	25-Oct-2022
Year of first publication:	2022
Language:	english
Abstract:	Concrete is the most prevalent manufactured material that has shaped the built environment, but the high-temperature production of cement, the main component of concrete, has a massive carbon footprint. It is shown that CO2 emissions during clinker production of cement can be circumvented by a metathesis reaction at room temperature in ball-mills, where the cement clinker is replaced by non-calcined limestone and alkali-activated binders/geopolymers. An amorphous intermediate (aNaSiCC) containing a random mixture of the ionic constituents in “molecular” dispersion is formed by mechanochemical activation of CaCO3 and Na2SiO3. This allows molecular transport during crystallization and low activated reactions, as precipitation of solids from liquids (nucleation limited and kinetically controlled) and solid-state transformations (diffusion-limited and thermodynamically controlled) have equal weight. Several steps of the hydration reaction could be resolved. Activating the amorphous aNaSiCC precursor with NaOH leads to a CSH-like phase with a C/S ratio of ≈1 containing some sodium. The carbonate components pass through a multistep crystallization from aNaSiCC via pirssonite and gaylussite to monohydrocalcite. The findings help unravel the interplay between thermodynamics and kinetics in complex reactions of alkali-activated binders and for CaCO3 crystallization in industrial and geochemical settings, where dissolved silicate is always involved.
DDC:	540 Chemie 540 Chemistry and allied sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-8029
Version:	Published version
Publication type:	Zeitschriftenaufsatz
License:	CC BY-NC-ND
Information on rights of use:	https://creativecommons.org/licenses/by-nc-nd/4.0/
Journal:	Advanced functional materials 32 7
Pages or article number:	2108126
Publisher:	Wiley-VCH
Publisher place:	Weinheim
Issue date:	2022
ISSN:	1616-3028
Publisher DOI:	10.1002/adfm.202108126
Appears in collections:	JGU-Publikationen