Ceramics-Silikáty 49 (3) 213-219 (2005)

HYDRATION AND LEACHING OF THE CEMENT – ZEOLITE COMPOSITE

P. Krolo, R. Krstulovic, P. Dabić, A. Bubić

This study has examined the effect of zinc-saturated zeolite on hydration processes and its stabilization in cement composites. Measurements were made on cement pastes with defined water/solid ratios, W/S, different contents (10-50 %) of zinc-saturated zeolite and the constant addition of 0.3wt.% of plasticizer admixture. The hydration process was studied by determining the heat effects of reactions using differential microcalorimetry and by measuring specific electric conductivity. Stabilization after solidification was evaluated by leaching test and UV/Vis spectrophotometrical analysis of zinc in elutes. The results show that higher zeolite addition brings lower hydration heat and relative hydration degree. Changes in specific conductivity and appearance of maxima on conductograms indicate that when the content of saturated zeolite in cement pastes increases, specific conductivity decreases, and the recorded maxima appear at later hydration and solidification times. Zinc concentration in elutes after the leaching depends on the duration of solidification, quantity of saturated zeolite and duration of rinsing after cement sample solidification. Low zinc concentration in elutes indicates that zinc-saturated zeolites can be successfully stabilized in Portland cement composites.

Keywords: Cement hydration, Cement composite, Zeolite, Harmful waste, Stabilization