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-N MR experiments show that the immobilization of Cd depends on Cd concentrati on 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 su spensions with large Cd content, there is precipitation of Cd(OH)(2); in su spensions with low Cd contents, Cd(OH)(2) is not detected, which supports t he hypothesis that Cd is sorbed on C-S-H. (C) 2001 Elsevier Science Ltd. At l rights reserved.