Advances in quantitative XRD analysis for clinker, cements, and cementitious additions

The Rietveld method allows a precise quantitative phase analysis of building materials. Thanks to the development of stable-functioning software and the use of high-performance detectors, a quantitative phase analysis by X-ray, including sample preparation, and measurement and evaluation, can be performed in fewer than ten minutes. This has made it possible to integrate the method into existing laboratory automation systems for process and quality control to provide a means of online monitoring. Due to the completely automated operating principle of the Rietveld software, no additional staff is required and the results are user-independent. The Rietveld method is now being employed in industrial laboratories and also in various cement plants owned by the Lafarge Group as the standard method of quantitative analysis of Portland Cement clinkers and Portland Cements (CEM I, CEM II A-L

Quantitative Rietveld phase analysis of calcium aluminate cements

Rietveld analysis is a powerful technique for obtaining quantitative data on the relative amounts of phases in a mixture of phases, such as cement. However, a good knowledge of crystallography and the development of a refinement strategy with synthetic phase mixtures are essential to obtain reliable results. This paper describes the use of Rietveld analysis for a range of calcium aluminate cements. The series of cements studied illustrates well how complexity of analysis and the level of accuracy attainable depends on the complexity of the cement. In cements of high Al2O3 content, with very low concentrations of minor elements, the analysis is relatively straightforward and high levels of accuracy can be obtained. In cements of intermediate Al2O3 content the analysis is complicated by the formation of solid solutions, but good results are still achievable after development and testing of the refinement strategy with phase mixtures. In cement of lower Al2O3 content the mineralogy is complex due to the presence of significant amounts of iron. Nevertheless, the phases which have most impact on the reactivity of the cement can still be determined with a good level of precision

Quantitative study of Portland cement hydration by X-ray diffraction/Rietveld analysis and independent methods

X-ray diffraction (XRD) is a powerful technique for the study of crystalline materials. The technique of Rietveld refinement now enables the amounts of different phases in anhydrous cementitious materials to be determined to a good degree of precision. This paper describes the extension of this technique to a pilot study of the hydration of a typical Portland cement. To validate this XRD-Rietveld analysis technique, its results were compared with independent measures of the same materials by the analysis of backscattered electron images (BSE/IA) and thermogravimetric analysis (TGA). In addition, the internal consistency of the measurements was studied by comparing the XRD estimates of the amounts of hydrates formed with the amounts expected to form from the XRD estimates of the amounts of anhydrous materials reacted. © 2004 Elsevier Ltd. All rights reserved