The crystal structure of a new calcium aluminate phase containing formate

Journal Article · Sun Aug 15 04:00:00 EDT 2021 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2021.106490· OSTI ID:23206256

Artioli, Gilberto ^[1]; Masciocchi, Norberto ^[2]; Giacobbe, Carlotta ^[3]; Castiglioni, Fabio; Ferrari, Giorgio ^[4]

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1. Department of Geosciences and Circe Center, University of Padua, via G. Gradenigo 6, 35129 Padua (Italy)
2. Department of Science and High Technology and To.Sca.Lab., University of Insubria, Via Valleggio 11, 22100 Como (Italy)
3. European Synchrotron Radiation Facility, 71 Avenue Des Martyrs, Grenoble 38040 (France)
4. Mapei S.p.A., via Cafiero 22, 20158 Milan (Italy)

A new calcium aluminate phase containing formate ions was synthesized and its crystal structure determined. This new phase is indicated as M-phase and was firstly observed in Portland cement pastes hydrated in presence of Ca-formate and in excess of water. The crystal structure of the M-phase was successfully solved in the R-3 space group of the trigonal system on the basis of synchrotron X-ray single crystal diffraction data. The structural model was confirmed by Rietveld refinement of the powder diffraction data acquired on the synthesized pure sample. The crystal structure of the M-phase is similar to that of ettringite, being characterized by columns of AlO{sub 6} octahedra alternating with groups of three edge-sharing CaO{sub 7} polyhedra. The formate ions (HCOO){sup −} share two oxygens with Ca polyhedra and are located in the interspace between the columns. The crystal structure of the M-phase testifies the strong interaction occurring between small organic molecules as formate and the calcium aluminate components of Portland cement.

• OSTI ID: 23206256
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Vol. 146; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINATES
CALCIUM
CRYSTAL STRUCTURE
FORMATES
HYDRATION
MONOCRYSTALS
OXYGEN
PORTLAND CEMENT
POWDERS
SPACE GROUPS
STRONG INTERACTIONS
STRUCTURAL MODELS
X-RAY DIFFRACTION