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A simple thermodynamic model on the cracking of concrete due to rust formed after casting

Agustín Sánchez-Deza (Department of Surface Engineering, Corrosion and Durability, National Centre for Metallurgical Research (CENIM-CSIC), Madrid, Spain)
David M. Bastidas (Department of Surface Engineering, Corrosion and Durability, National Centre for Metallurgical Research (CENIM-CSIC), Madrid, Spain)
Angel La Iglesia (Institute of Geosciences (IGEO), CSIC-UCM, Madrid, Spain)
Jose-María Bastidas (Department of Surface Engineering, Corrosion and Durability, National Centre for Metallurgical Research (CENIM-CSIC), Madrid, Spain)

Anti-Corrosion Methods and Materials

ISSN: 0003-5599

Article publication date: 2 May 2017

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Abstract

Purpose

The purpose of this study is to use thermodynamic data to estimate the pressure exerted by the crystallization of iron oxyhydroxides following the equation proposed by Correns and Steinborn.

Design/methodology/approach

Standard free energy and molar volume data have been considered for goethite, lepidocrocite, magnetite and hematite, which are described in the literature as the most commonly found mineral phase rust constituents.

Findings

The studied mineral phases generate higher to lower crystallization pressure values in the following order: goethite > lepidocrocite > hematite > magnetite. The crystallization pressures calculated for these phases are in the 32-350 MPa range, which is higher than the tensile strength of concrete (of the order of 0.2-10 MPa) and thus leads to failure of the cover concrete.

Originality/value

The aim of this paper is to shed light on this issue by calculating the stresses generated by the crystallization of iron oxide from a supersaturated solution using thermodynamic data. A deliberately simplistic method was proposed, taking as reference the Correns–Steinborn model (Correns and Steinborn, 1939; Correns, 1949). The crystalline phases considered in this paper are those most commonly found in the literature as rust constituents, that is, goethite (α-FeOOH), lepidocrocite (γ-FeOOH), magnetite (Fe3O4) and hematite (α-Fe2O3). The FeO synthetic phase was also included as a reference.

Keywords

Acknowledgements

The authors express their gratitude to Project No. DPI2011-26480 from CICYT, Spain, for financial support and to K10 Architects, Alicante, Spain for supplying the specimens.

Citation

Sánchez-Deza, A., Bastidas, D.M., La Iglesia, A. and Bastidas, J.-M. (2017), "A simple thermodynamic model on the cracking of concrete due to rust formed after casting", Anti-Corrosion Methods and Materials, Vol. 64 No. 3, pp. 335-339. https://doi.org/10.1108/ACMM-11-2015-1602

Publisher

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Emerald Publishing Limited

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