Reference Materials and Proficiency Testing for Validating X-Ray Powder Diffraction Measurements of Cement Composition
Paul E. Stutzman
Validation of quantitative X-ray powder diffraction measurements traditionally involved compounding test mixtures of known phase compositions. Validation is particularly important with the Rietveld method as the normalization will obscure bias. ASTM C1365, Standard Test Method for Determination of the Proportion of Phases in Portland Cement and Portland-Cement Clinker Using X-Ray Powder Diffraction, employs a laboratory qualification using replicate determinations of certified reference materials, such as the NIST SRM clinkers. The performance metrics for repeatability and reproducibility precision and for bias in ASTM C1365 are based on multiple inter-laboratory studies and standardized procedures for estimating precision. An alternate validation approach can be found in a modified routine proficiency testing, where a group of laboratories provide a single analysis on each of two cements using the ASTM C1365 qualification criteria. Quantitative feedback provided in graphical format allow participants to assess results for random and systematic error. Proficiency testing of this sort provides participating laboratories with a quantitative assessment of their performance relative to peers using a wider range of materials encompassing the broad spectrum of modern hydraulic cement production.
20th International Conference of Building Materials
Reference Materials and Proficiency Testing for Validating X-Ray Powder Diffraction Measurements of Cement Composition, 20th International Conference of Building Materials, Weimar, -1, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925966
(Accessed May 30, 2023)