The corrosion behaviour of five TRUW base and reference glasses in distilled water has been investigated for times up to 8 months. The glasses were chosen to evaluate some of the main features of the basaltic slag as produced by the prototype FLK incinerator, i.e. the iron valence state and the relative influence of Al2O3 vs FeOx. Diffusion processes control the corrosion for times below 80 d at 90°C at the SA.V-1 value currently considered (1 cm-1), resulting in the formation of complex films enriched in Al, Fe and Mg over 200 nm thick. The partial replacement of 10 mole 7 Fe2Ox by Al2O3 improves the chemical resistance and strongly accelerates saturation of the leachate for Si, and apparently also for Na and K. The iron valence
state in the glass does not seem to influence the corrosion behaviour. When leaching at temperature up to 200°C, the surfaces of all glasses crystallize, while the corrosion rates do not decrease with time. At SA.V−1 ≠ 0.1 cm−1 , 90°C, the weight losses increase by a factor up to 10 relative to SA.V−1 ≠ 1 cm−1 , 90°C, and the initial diffusion controlled stage might be followed by matrix dissolution reactions.