Hexavalent chromium and some trace metals in concrete from buildings of different ages in northern Italy

The content of total hexavalent chromium (CrVI), total chromium (Cr) and other metals (Fe, Mn, Ni and Co) was determined in the cement matrix of concrete present in samples collected in both old and recent buildings located in the town of Modena (northern Italy). The cement matrix of concrete was obtained by eliminating the aggregate components by means of disaggregation and was ground until it could pass through a 63-μm-sieve. In addition, samples of bagged commercial cements were considered. Metal determination was obtained by inductively coupled plasma optical emission spectroscopy after strong acid dissolution (HCl–HNO3). Total Cr(VI) determination was obtained after mild acid attack (HCl) and analysed by UV–Vis spectrophotometry. Analytical data values obtained indicate that the highest concentrations of metals were found in concrete and in bagged cement samples characterized by high Fe concentration. High Cr(VI) concentrations both in the cement matrix of concrete and in cement samples were found in total Cr-rich samples. Cr(VI) concentrations were about 20–30% of total Cr. The data obtained indicate that secondary raw materials and industrial by-product powders utilized in the modern cement industry may significantly increase Cr(VI) in concrete.