Uptake of actinides by calcium silicate hydrate (C-S-H) phases

Cm(III) retention by calcium silicate hydrate (C-S-H) gel and secondary alteration phases in carbonate solutions with high ionic strength: A site-selective TRLFS study

“…Häußler et al . 6 determined R d values of 4 × 10 5 L/kg for the sorption of Am(III) on C-S-H. R d values determined for Eu(III) sorbed on C-S-H phases by Pointeau et al . 22 and Tits et al .…”

“…Some previous studies focused on the sorption behavior of trivalent actinides and lanthanides on C-S-H gel 6,20,22,23 . Häußler et al .…”

“…Concrete contains hardened cement paste (HCP), a mixture of mineral phases such as calcium silicate hydrate (C-S-H), portlandite, and calcium aluminate hydrates 1 . HCP and especially C-S-H are known to immobilize tri-, tetra- and hexavalent actinides such as Cm(III), Am(III), Np(IV), Pu(IV) and U(VI) potentially released from spent nuclear fuel (SNF) 2–6 . C-S-H is a sheet silicate consisting of polyhedral CaO planes, SiO tetrahedra chains or dimers, and interlayers filled with water or cations such as Na + , K + or Ca 2+ , similar to a defected 14 Å tobermorite-like structure.…”

Molecular dynamics simulation of the interaction of uranium (VI) with the C–S–H phase of cement in the presence of gluconate

“…The sorption behavior of actinides on C-S-H phases has already been studied recently, and a strong effect of the Ca/Si ratio has been found (Pointeau et al, 2004;Harfouche et al, 2006;Tits et al, 2011;Gaona et al, 2012;Macé et al, 2013;Häußler et al, 2018;Tits and Wieland, 2018). Even though in ordinary Portland cement we can observe predominantly C-S-H phases with Ca/Si ratios higher than 1.5, lower ratios are typical for "low-pH" cements with added fly ash and silica fume, and in degraded cement pastes because of the decalcification (Glasser et al, 2008).…”

Comparative study of Eu and U sorption on cementitious materials in the presence of organic substances

“…The obtained R d values for the system 223 U (c = 7•10 −8 mol L −1 ) on CSH 1.0 are in the order of 10 4 L kg −1 (Table 3) as expected (c.f. [24,25]), they do not show a dependence on the phase ratio and therefore they can be evaluated using the K d -model. In contrast with the uptake of 233 U on HCP CEM I, the sorption on CSH 1.0 is linear, which is probably related to its homogeneity and stability.…”