Title

The Influence of Slightly and Highly Soluble Carbonate Salts on Phase Relations in Hydrated Calcium Aluminate Cements

Abstract

The addition of slightly (CaCO3) and highly soluble (Na2CO3) carbonate salts is expected to favor the formation of carboaluminate phases in hydrated calcium aluminate cements (CACs). A multi-method approach including X-ray diffraction, thermogravimetric analysis, and thermodynamic calculations is applied to highlight that the "conversion phenomena" in CACs cannot be mitigated by the formation of carboaluminate phases (monocarboaluminate: Mc and hemicarboaluminate: Hc) which are anticipated to form following the addition of carbonate salts. Here, carboaluminate phase formation is shown to depend on three factors: (1) water availability, (2) carbonate content of the salts, and their ability to mobilize CO32- species in solution, and (3) lime content associated with the carbonate salt. The latter two factors are linked to the composition and solubility of the carbonate agent. It is concluded that limestone (CaCO3), despite being a source of calcium and carbonate species, contributes only slightly to carboaluminate phase formation due to its low solubility and slow dissolution rate. Soluble carbonate salts (Na2CO3) fail to boost carboaluminate phase formation as the availability of Ca2+ ions and water are limiting. Detailed thermodynamic calculations are used to elucidate conditions that affect the formation of carboaluminate phases.

Department(s)

Materials Science and Engineering

Comments

The authors acknowledge the financial support for this research provisioned by the University of California, Los Angeles (UCLA), and National Science Foundation (CMMI: 1066583).

Keywords and Phrases

Calcite; Calcium carbonate; Cements; Hydration; Lime; Salts; Sodium Aluminate; Sodium Carbonate; Sodium compounds; Solubility; Thermogravimetric analysis; X ray diffraction, Calcium aluminate cement; Carbonate content; Carbonate species; Dissolution rates; Multi-method approach; Phase formations; Thermodynamic calculations; Water availability, Carbonation

International Standard Serial Number (ISSN)

0022-2461; 1573-4803

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2016 Springer New York LLC, All rights reserved.

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