Formation mechanisms of corrosion-resistant oxide films in steel reinforced low-carbon concretes

Steel reinforcement corrosion in concrete structures is the most prevalent global challenge for cities and their infrastructure. Globally, 2.2 trillion Euro are spent each year to prevent, mitigate, and repair civil concrete infrastructure damage due to corrosion of steel reinforcement. Innovative low-CO2 concrete technologies, such as alkali-activated materials, have gained global research attention due to their potential to decarbonize civil infrastructure as well as their demonstrated improved durability, when compared to conventional concrete materials. However, their application is limited by critical gaps-in-knowledge concerning the corrosion mechanisms occurring at the steel-concrete interface.

This project aims to understand the effect of various chemical and physical nano-environments (e.g., pH, relative humidity, SOx, O2) on the formation mechanisms of corrosion-resistant oxide films in embedded steel reinforcement of alkali-activated materials, produced with near neutral salts. Specific objectives are to: (i) determine the phase assemblage (type and amount), chemistry and mineralogy, as well as porous network of oxide films forming in steels under controlled environments, and when embedded in near neutral salts activated materials; (ii) elucidate the factors influencing the stability of oxide films as a function of the chemical changes experienced by near neutral salt activated materials, at different extents of reaction; and (iii) reveal the existing correlations between the oxide film characteristics and the electrochemical responses of steel in conditions relevant to reinforced concretes.

The successful applicant will achieve these objectives by accessing the state-of-the-art unique facilities available in the Bragg Centre of Materials Research, the UKCRIC National Centre of Infrastructure Materials and the Institute for Functional Surfaces. This includes in-situ microscopy (i.e. computerized tomography, cryo-scanning transmission electron microscopy), advanced environmental spectroscopy (i.e., photoelectron spectroscopy), and bespoke electrochemical devices and electrochemistry facilities. Synchrotron-based techniques (imaging, spectroscopy and diffraction) available at the Diamond Light Source will also be used in this study.

This research project will be conducted in the University of Leeds, and the supervisory team comprises senior academics with expertise in materials science and surface engineering, internationally recognised as world-leading researchers in the design, advanced characterisation and performance assessment of cementitious materials, as well as for corrosion studies of metals for energy and infrastructure applications.