Analysis of the Chromium Concentrations in Cement Materials

Chromium is an indelible non-volatile trace element of raw materials used in cement clinker production. This work is focused on the study of the content of total chromium and soluble hexavalent chromium in cements. Cements samples of various types (CEM I, CEM II, CEM III and CEM V) were investigated in the experiment. Total chromium content in cements as well as the chemical composition of cement samples was measured by using X-ray fluorescence spectrometry (XRF). The average concentrations of the total chromium in cements vary from 178.5 to 257.3 mg per kg of cement. The concentration of the soluble chromium (VI) was measured in cement leachates using colorimetric method. The average concentrations of hexavalent chromium ranged from 0.5 to 2.46 mg/kg. The results of chromium (VI) measurements in water leachates confirmed that only a small part of total chromium was extracted from the cement into the water environment. The percentage of water soluble chromium (VI) varied from 0.19 to 1.38%. In addition, X-ray powder diffraction and (XRD) and infrared analysis (FTIR) were used for the cements investigation. Summarizing the results of chromium (VI) monitoring, approximately 75% of investigated cements fulfilled the Slovak eco-labelling requirement.