Investigation of self-desiccating cement-based materials for dihydrogen sequestration: Interactions between γ-MnO2Ag2CO3 getter and the cement matrix

Mitigating the release of dihydrogen resulting from metal corrosion or water radiolysis is an important issue for the disposal of certain types of cemented radwaste packages. The approach investigated in this work consists in adding an oxide getter (γ-MnO2Ag2CO3) to the cement matrix. Since the efficiency of the getter decreases under wet environment, two self-desiccating binders, a calcium sulfo-aluminate cement (CSA) and a magnesium potassium phosphate cement (MKP), are used to obtain significant desaturation of the pore network by the sole hydration reactions. It is shown that the getter slightly influences the rate of cement hydration at early age (acceleration for MKP, retardation for CSA), but has no effect afterwards. Sorption of ions released by the dissolution of cement phases onto γ-MnO2 is evidenced, as well as partial or total destabilization of silver carbonate. Nevertheless, the getter still enables to reduce strongly the outgassing of dihydrogen from mortars encapsulating Al-metal.