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Quantification of Portland cement clinker phases by
means of Rietveld analysis when using secondary fuels
Dr. M. Paul, Dyckerhoff AG, Wiesbaden, Germany
X-ray fluorescence and optical microscopy are common methods for evaluating the quality in cement clinker production. The application of X-ray diffraction offers an additional tool for cement clinker characterisation where the X-ray pattern is being analysed by means of the so-called Rietveld method. The Rietveld method in conjunction with suitable analysis programs and crystal structure data allows, when using optimised settings for instrument geometry and measuring conditions, the rapid quantification of phase contents in technical clinkers with high accuracy. In particular, the comparison with the commonly used Bogue calculation shows the advantages of the Rietveld method, since production technology can cause the expected theoretical phase composition in the chemical equilibrium obtained by the Bogue calculation to deviate from the actual phase assemblage present. In addition, the Rietveld method yields crystallographic information which cannot be obtained by other techniques or is accessed just by time- and labour-intensive analyses. However, the precise knowledge about clinker mineralogy is essential particularly for predicting material properties. The increasing use of secondary fuels in clinker production often affects the clinker burning which can lead to drastic changes in cement properties. The fast analysis of changes in clinker phase assemblage by means of the Rietveld method allows accurate monitoring of changes in production in order to obtain quickly a high quality level. A few examples demonstrate how unintentionally introduced changes in clinker burning can be detected in a short time in order to avoid possible customer complaints.
Summary CEMENT INTERNATIONAL 05/2004 pp 104-109
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