抄録
Chemical state change of trace chromium and zinc in normal Portland cement during hydration was monitored using X-ray absorption fine structure analysis. It was found that the peak area due to hexavalent chromium was decreased monotonously with the material age, i.e., with the cement hydration. This indicates that the trace hexavalent chromium intrinsically contained in cement is gradually reduced to trivalent chromium during the hydration process and thus its toxicity and solubility decreases with elapsed time. Furthermore, peaks peculiar to ZnO were also observed for cement in Zn K-edge XANES spectra, and their intensities were monotonously decreased with hydration of cement. This indicates that zinc atom coordinated by four oxygen atoms was decreased with hydration of cement.
