Experimental evidence of the influence of iron on pore water radiolysis in cement-based materials

Hydrated tricalcium silicate based cement pastes or mixes, with the addition or not of amorphous iron oxyhydroxide, were irradiated for I year in a closed system (7 radiation) with the aim of provoking radiolysis of the alkaline pore solution (pH > 13). The data collected (on-line monitoring of the total pressure and the H-2 content in 500 cm(3) mini-containers irradiated at 45 degrees C and 1.07 kGy/h with V-gas/V-paste approximate to 1) enable us to conclude that the addition of 1% of FeOOHam, gives rise to about 26% of additional residual H-2 after 1 year. This result appears to validate the hypothesis of a partial mobilisation of the and O- radicals in a continuous process of Fe(III) <-> Fe(II) oxidation-reduction, at the expense of their action within the Allen type reaction chain that is responsible for the recycling of H-2. Despite the complexity of the porous material, the simulation of the experiment with the CHEMSIMUL application leads to a result that is quite close, and stresses the importance of the kinetic coupling between gas transport in the porous material and the reaction system. (C) 2013 Elsevier B.V. All rights reserved.