The effect of foreign ions on the reactivity of the CaO–SiO 2 –Al 2 O 3 –Fe 2 O 3 system Part II: Cations

Cement and Concrete Research (Impact Factor: 3.85). 10/2001; 32(3):463-469.

ABSTRACT The subject of this paper is the effect of foreign cations on the reactivity of the CaO – SiO 2 – Al 2 O 3 –Fe 2 O 3 system. One reference mixture and eighteen modified mixtures, prepared by mixing the reference sample with 1% w/w of chemical grade MnO 2 , CuO, were studied. The effect on the reactivity is evaluated on the basis of the free lime content in samples sintered at 1200 and 1450 °C. At 1200 °C, the reactivity of the mixture is greatly increased in the presence of Cu and Li oxides. Based on their effect at 1450 °C, the added elements can be divided into three groups. W, Ta, Cu, Ti and Mo show the most positive effect, decreasing the free CaO (fCaO) content by 30 – 60%, compared with the pure sample. Cr and B cause an increase of fCaO content, while the rest of the elements exhibit a marginal positive effect. According to their volatility at 1450 °C, the added compounds can be subdivided into three groups of low (Ti 4 + , Cu 2 + , Mo 6 + , W + 6 , V 5 + , Zn 2 + , Zr 4 +), moderate (Cr 6 + , Co 3 + , Ni 2 + , Mn 4 +) and high volatility (Cd 2 + , Pb 2 +). All burned samples, analyzed by means of X-ray diffraction, have a final mineralogical composition, which corresponds to the structure of a typical clinker. D

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