Out of our bubble ::an interdisciplinary collaboration between archaeology and civil engineering to understand the corrosion of iron in porous media

This study investigates similarities in corrosion product (CP) formation within macro-voids of archaeological iron artifacts and reinforced concrete. X-ray computed tomography (XCT), SEM-EDS, and μRaman spectroscopy reveal shared patterns in CP layer development: an outer Fe(III) layer (goethite) and an inner layer of mixed Fe(II) and Fe(III) oxides (primarily magnetite) growing inward. The formation of the corrosion products in both systems is influenced by pH gradients, Fe(II)-to-Fe(III) transitions, and matrix composition. In archaeological iron artifacts, the halted precipitation process over millennia suggests CP growth ceased before voids were completely filled, as corrosion progressed elsewhere.