How does the pore solution chemistry influence the passivation of reinforced alkali‐ and salt‐activated slag materials?

Service life predictions of reinforced concrete structures are underpinned by the passivation film chemistry, structure, and thickness. In this work, we present how the formation of passive films at the steel–concrete interface of reinforced alkali‐ and salt‐activated slag materials can be affected...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2024-03, Vol.107 (3), p.1625-1635
Main Authors: Gevaudan, Juan Pablo, Timounay, Yousra, Mayrhofer, Leonhard, Zarshenas, Mohammad, Moseler, Michael
Format: Article
Language:English
Subjects:
alkali‐activation
Cements
characterization
Charge transfer
Chemical composition
Complexity
Concrete structures
corrosion
passivation
Passivity
Phase composition
R&D
Reinforced concrete
Reinforcing steels
Research & development
salt‐activation blast furnace slag
Service life
Slag
Solution chemistry
Thickness
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Summary:Service life predictions of reinforced concrete structures are underpinned by the passivation film chemistry, structure, and thickness. In this work, we present how the formation of passive films at the steel–concrete interface of reinforced alkali‐ and salt‐activated slag materials can be affected by the pore solution chemistry, namely, pH, Eh, and chemical composition. Thermodynamic simulations are used to illustrate the time‐dependent changes to the pore solution chemistry, where estimated electrical conductivities of the pore solution are used as a single‐value parameter to understand the solution complexity and capacity for charge transfer. A set of passivation reactions are proposed to understand the effects of OH− and HS− (reduced sulfur species) competition on the passivation pathways. These passivation reactions become more complex considering that a reducing pore solution might not establish until 3 days into the curing process—a crucial factor explaining the significant differences in the phase composition of passive films of activated slag materials (FeOOH, FeS). This study sheds light on recent progress in understanding these initial passivation reactions, emphasizing the essential role of material design and, therefore, the pore solution chemistry of these cements, along with significant insights for vital research and development concerning the corrosion durability of activated slag materials.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.19342