| Clinker acquired from a cement calcinations simulation of raw materials containing Cd and Ni chemical reagents were used to prepare cement paste.According to the electron probe microanalysis (EPMA) of point,line and surface analysis,the whole distribution situation of Cd and Ni in cement paste and the concrete distribution characters in different mineral phases were identified.The results show that,Cd and Ni both accumulate in the cement paste:the elemental distribution maps illustrate that Cd accumulates in the CH crystal,the main existing form of Cd in the cement paste is Cd/Ca hydroxides and the line analysis results further indicate that the Cd content in the CH crystal decreases gradually from the inside of the crystal to the outside; the surface and point analysis shows that the Cd content in other mineral phases is small,especially the point analysis results indicate that Cd concentration in middle phases is lower than 1%.The high concentration areas of Ni are all small,and the elemental distribution maps and the line analysis results both provide evidences that Ni and Mg have well correspondence in distribution,indicating that Ni is mainly existed as the Ni-Mg compound with independent random distribution in the cement paste; the surface and point analysis reveals that Ni content in other mineral phases is small,particularly the point analysis results indicate that the Ni concentration in middle phases is around 1%. |
