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Towards mastering the long-standing challenge of ageing infrastructures in corrosive environments

Periodic Reporting for period 1 - TAMING CORROSION (Towards mastering the long-standing challenge of ageing infrastructures in corrosive environments)

Reporting period: 2020-01-01 to 2021-06-30

The socio-economic burden of replacing and repairing infrastructures due to corrosion is staggering. In the EU alone, estimates are in the range of 250 billion € annually, with an expected steep increase over the coming decades. This urgently calls for new, cost-effective corrosion mitigation strategies to prolong the useful life of ageing civil infrastructures. Electrochemical corrosion protection (ECP) methods have a large potential to play a key role in addressing this challenge. However, to match these expectations, advances are needed in both science and engineering. The aim of this proposal is thus to develop the scientific basis to unlock the potential of ECP as an innovative solution to the grand challenge of rapidly deteriorating infrastructures. The objective is to integrate all relevant physical, chemical, and electrochemical processes into a quantitative model framework for the systematic study of fundamental processes and evaluation of solution strategies.
The work carried out so far includes experiments to quantify the spatial distribution of pH and oxygen in the near field of homogeneously polarized electrodes embedded in porous media, as a function of both the porosity of the porous medium (quartz sand) and the ECP operating conditions. Furthermore, a thermodynamic database was compiled from literature data available on iron in different electrolytes, including near pH-neutral solutions as well as alkaline, cementitious systems. Finally, focused-ion beam / scanning electron microscopy was used to generate tomographic 3D information on the pore network and microstructure of the interfacial zone of steel embedded in cementitious media. A reactive transport model is being established that integrates the microstructural features, the chemical reactions (thermodynamics) and the electrochemical reactions at the metal surface.
The scientific impact of this proposal can be found mainly in delivering a model for ECP that holistically addresses the complex system of ECP of steel in reactive porous media: coupling reactive multi-species and moisture transport in porous media with rigorous corrosion science/electrochemistry. This permits to reliably predict the system behaviour and thus to enhance mechanistic understanding of ECP. The technological benefit of this work can be found in paving the way towards a new generation of scientifically sound engineering tools of ECP.
Overview of processes addressed in this project