SEM examination of clinkers containing foreign elements

In this paper, the structure of clinker, modified by the introduction of foreign elements in the raw mix, is examined. One reference mixture and 16 modified mixtures, prepared by mixing the reference sample with 2.5% w/w of chemical grade CuO, MoO3, WO3, ZnO, Nb2O5, Ta2O5, MnO2, V2O5, Li2O, Co2O3, NiO, SnO2, SrO, CrO3, TiO2 and BaO2 were studied. The samples, after sintering at 1450 °C, were examined using a scanning electron microscope. As it is concluded the incorporation of foreign elements in clinker considerably affects the texture of the silicates and the interstitial material. Nb, Mo, Ta, Ti, Co, Ni and Mn are preferentially incorporated in the melt. Cr and Sr are found mainly in the silicates while W and V seem to be equally distributed into the clinker compounds. Cu, Ni and Sn are mainly incorporated in solid solutions combining with CaO. Li and Sr modify considerably the texture of alite and belite indicating a strong effect on the growth of the calcium silicate crystals.