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Direct Determination of Cement Composition by X-Ray Diffraction

Project Summary

The most widely used method of estimating the potential phase composition of Portland cement is the Bogue calculation from its oxide analysis. However, it is well known that the phase abundance calculated by Bogue method doesn’t provide the actual phase composition. X-ray powder diffraction (XRD) analysis provides an alternative direct Rietveld method for phase quantification. More recently, the Rietveld method show an improvement in both within (repeatability) and between laboratory (reproducibility) precision. Over the past decade, the composition of finished cements has changed with the use of limestone additions and synthetic gypsum. The use of XRD allows accurate determination of limestone content, quantification of the different types of sulfate phases and monitoring free lime content. Although, American Standard Test Method (ASTM) C1365 outlines a process for XRD, very little effort has been made to incorporate this method into routine production and qualification testing. The objective of this project is to advance the use of Quantitative X-Ray Diffraction (QXRD) method for cement phase quantification analysis. The main tasks to accomplish this objective are (i) Determine barriers preventing the progression of XRD in production testing and solutions to overcome these barriers, (ii) Develop protocols for determining cement composition by XRD for all ASTM C150 and C595 types of cements, (iii) Determine the effects (if any) on cement production if QXRD is used to quantify the cement phases, and (iv) provides recommendation on incorporating QXRD related parameters in cement specification. Direct quantification of cement phases provides a more complete accounting of the actual phase compositions, which should provide a better basis for relating mineralogical composition to performance characteristics and improving predictive capability for cements.

Project Number

0-6941

Status

Completed

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