Phase-field-based chemo-mechanical modelling of corrosion-induced cracking in reinforced concrete
File(s)
Author(s)
Korec, Evzen
Type
Thesis
Abstract
In this thesis, a new model for corrosion-induced cracking in reinforced concrete is presented. This complex chemo-mechanical phenomenon is of great practical importance because it results in the spalling or delamination of concrete cover, significantly contributing to the premature degradation of concrete structures. To overcome the limitations of currently available models, the state-of-the-art knowledge of the underlying processes has been incorporated into three interconnected sub-models for: (i) the reactive transport of involved species and iron precipitation in concrete pore space, (ii) corrosion-induced pressure resulting from the concurrent constrained accumulation of compressible rust in a dense rust layer and in a concrete pore space, and (iii) the quasi-brittle fracture of concrete predicted with a phase-field fracture model. The resulting chemo-mechanical model, in many aspects the first of its kind, is demonstrated to accurately predict corrosion-induced cracking under both natural and accelerated conditions, paving the way for computational corrosion testing supporting or even replacing impressed current tests.
For the first time, corrosion-induced cracking of reinforced autoclaved aerated concrete (RAAC) panels is simulated. Also, a solution is proposed to the 25-year-old problem of why accelerated impressed current tests lead to the slower propagation of cracks (with respect to the thickness of the corroded steel layer) than in natural conditions and thus underestimate sustained corrosion-induced damage. In view of recent experimental findings, it is suggested that the
phenomenon can be attributed to the variability of rust composition and density, specifically to the variable ratio of the mass fractions of iron oxide and iron hydroxide-oxide, which is affected by the magnitude of the applied corrosion current density. In addition, the model allows for the calculation of a newly proposed crack width slope correction factor, which extrapolates the surface crack width measured during accelerated impressed current tests to corrosion in natural conditions.
For the first time, corrosion-induced cracking of reinforced autoclaved aerated concrete (RAAC) panels is simulated. Also, a solution is proposed to the 25-year-old problem of why accelerated impressed current tests lead to the slower propagation of cracks (with respect to the thickness of the corroded steel layer) than in natural conditions and thus underestimate sustained corrosion-induced damage. In view of recent experimental findings, it is suggested that the
phenomenon can be attributed to the variability of rust composition and density, specifically to the variable ratio of the mass fractions of iron oxide and iron hydroxide-oxide, which is affected by the magnitude of the applied corrosion current density. In addition, the model allows for the calculation of a newly proposed crack width slope correction factor, which extrapolates the surface crack width measured during accelerated impressed current tests to corrosion in natural conditions.
Version
Open Access
Date Issued
2024-06-03
Date Awarded
01/09/2024
License URL
Advisor
Martínez-Pañeda, Emilio
S. Wong, Hong
Sponsor
Imperial College London
Publisher Department
Department of Civil and Environmental Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)