Chrom, Nickel und Zink in Klinker und Zement : Einbau, Eigenschaftsänderung und Auslaugung

The aim of the work in the field of building chemistry was the investigation of the influence of higher concentrations of trace elements (e.g. Cr, Ni and Zn) on the production and the use of cement. The pure clinker phases C3S, C3A and C4AF as well as different industrial raw meals were doped with heavy metal oxides in different concentrations and burned. Different analyses were done on the unhydrated samples, e.g. determination of free lime, X-ray diffraction (XRD),
scanning electron microscopy (SEM) in combination with energy disperse analysis of X-ray (EDAX). In order to examine the hydration, the samples were ground to the same fineness (clinker together with sulphate). The hydration was measured by differential scanning calorimetry and XRD and the hydration products were investigated with SEM and EDAX. Besides, the initial setting and the development of the strength of cement pastes were determined.
For the leaching tests, again, doped cements were produced. On these cements and mortars produced from them, three different leaching tests were performed (leaching of cements, tank leaching test and DEV-S4 procedure).
The investigations showed, that low concentrations of Cr, Ni and Zn neither have influence on the production of pure clinker phases and cements nor on the hydration of binders made from these. For changes at higher concentrations the composition of the cements is very important (main and minor elements).