Aqueous-solid solution thermodynamic model of U(VI) uptake in C-S-H phases

► Uptake of U(VI) by C-S-H is explained with a multi-site solid solution thermodynamic model. ► Development of the model is based on wet chemistry data, spectroscopy and C-S-H structure. ► Model considers different types of C-S-H forming during cement hydration or degradation. ► Model correctly accounts for sorption trends of U(VI) on C-S-H and Hydrated Cement Paste. ► Different scenarios can be assessed with the model, e.g. U(VI) behaviour upon carbonate intrusion.