Speciation of cadmium in cement Part II.: C3S hydration with Cd2+ solution

C3S was hydrated with Cd-containing solutions to prepare suspensions [water/solid (w/s) ratio = 100] and pastes (w/s = 0.45). XRD, EXAFS, and Cd-113-NMR experiments show that the immobilization of Cd depends on Cd concentration and water/cement ratio. For pastes, there is formation of a mixed Ca/Cd hydroxide, but a fraction of Cd ions is probably sorbed on the C-S-K. In suspensions with large Cd content, there is precipitation of Cd(OH)(2); in suspensions with low Cd contents, Cd(OH)(2) is not detected, which supports the hypothesis that Cd is sorbed on C-S-H. (C) 2001 Elsevier Science Ltd. Atl rights reserved.