Title:
On the Formation of Al/Fe-AFm Solid Solutions During Hydration of Fe-Rich Binders
Author(s):
Aurore Lechevallier, Mohend Chaouche, Jérôme Soudier and Guillaume Renaudin
Publication:
Symposium Paper
Volume:
362
Issue:
Appears on pages(s):
547-557
Keywords:
AFm layered hydrate; Fe-rich binder; Low-CO2 binder; Rietveld refinement; solid solutions; Vegard law.
DOI:
10.14359/51741010
Date:
6/14/2024
Abstract:
New hydraulic binders have been extensively studied as potential substitutes for Ordinary Portland Cement worldwide. Very often these binders contain a significant amount of iron and aluminum oxides, as a Ca4Al2-xFe2+xO10 like phase and generate AFm phases as a hydration product. To properly characterize the hydration process (anhydrous phases consumption versus hydrates precipitation), investigating the existence of (Fe/Al)-AFm solid solutions becomes important.
Consequently, layered AFm samples intercalated with various anions (nitrate, chloride, and carbonate) and with varying Fe/Al molar ratios were synthesized. Rietveld refinements were conducted to control the existence of the solid solutions between the two trivalent metallic end-members.
This study presents definitive evidence establishing continuous solid solutions within the three investigated systems of layered AFm phases containing nitrates, chlorides, or carbonates. These solid solutions conform to the Vegard’s law, and reflect the distances between trivalent cations, notably expanding with the iron substitution rate (in accordance with ionic radius RAl3+ = 0.53 Å and RFe3+ = 0.64 Å). A similar evolution was observed for the three series of AFm compounds.