MECHANISMS OF METAL STABILIZATION IN CEMENTITIOUS MATRIX - INTERACTION OF C3S PASTE AND COPPER-OXIDE

Cement constituent-tricalcium silicate (C3S)-was synthesized as a mode l binder for mechanistic investigation on solidification/stabilization process. X-ray diffraction, scanning electron microscopy, and energy dispersive analysis of X-ray using micro-probe and line scanning techn iques were used in this study. A sandwich sample consists of C3S paste , CuO, and copper foil layers was developed for investigating the poss ible interactions between hydrated C3S and CuO which served as model m etal-bearing sludge. We verify that the interactions between C3S paste and CuO can be reasoned in two models. The chemical interactions do o ccur at the interfacial zone between the hydration product containing Ca of C3S paste and CuO, and a new phase was developed which consists of Ca and Cu. The new phase identified here probably has Ca to Cu rati o about 0.59. The other phenomena observed was that the hydration prod uct containing Ca and Si of C3S paste and CuO system do not reveal any evidences for the possible chemical interactions but only physical di ffusion at the interfacial zone. The interactions of C3S and CuO were defined as two models: chemical reaction with new phase generated and physical diffusion.