MEASURING Cr~(6+) IN CEMENTS AND ADMIXTURES

摘要

Quantitatively, the Cr~(6+) proportion in cement is meagre, yet the significance to its measuring comes from the effects it inflicts upon the health of the cement-placing workers. In March 2003, the European Union adopted an amendment to the European Directive 76/769/EEC restricting the Cr~(6+) presence in cement to 2 mg/kg. This amendment has raised the necessity of developing a method for measuring Cr~(6+) in accordance with the requirements in the European norms in the field. The method is applied in measuring Cr~(6+) in raw materials, cements and admixtures, and uplifts the competitiveness of Romanian cements on the European Union market. The principle of the method is based on measuring spectrocolourimetrically Cr~(6+) dissolved in water after eliminating any possible ipterference from reducing elements. The efficiency of the method has been fine tuned by measuring Cr~(6+) in controlled amounts in clinker samples. The paper also reveals the results obtained at measuring Cr~(6+) in Romanian raw materials, cements and admixtures.