Book Description

X-ray powder diffraction analysis is used in the cement industry as a direct analytical method for phase identification and quantitative analysis of clinker and cements. Quantitative methods initially relied on the development of calibration curves, employing multiple reference mixtures of cement phases with an internal standard to develop a plot of diffraction peak intensity ratios vs. mass fraction ratios. Obstacles to this approach were the availability of reference standards that adequately replicated those phases in the clinker or cement, and the ability to accurately measure diffraction peak intensities because of severe peak overlap. The Rietveld method for analysis of powder diffraction data addresses both of these difficulties through use of refineable crystal structure models to calculate the individual phase diffraction patterns and a whole-pattern fitting procedure to minimize the difference between the measured diffraction pattern and set of calculated phase patterns. This approach has revolutionized the application of X-ray powder diffraction in many scientific disciplines, including that of hydraulic cements, but can be a complicated method to learn. This tutorial is intended to provide an introduction to the application of Rietveld analysis to portland cement clinker and cements using examples developed from one of the NIST SRM clinkers and two portland cements.