Analysis of VDZ 100 (CEM I), 200 (CEM II) and 300 (CEM III) SRMs using ARL X’TRA Companion X-ray Diffractometer

Significance of the topic

The accurate phase analysis of cement is central to quality control, process optimization, and regulatory compliance in cement manufacturing. Standard Reference Materials (SRMs) such as VDZ 100 (CEM I), VDZ 200 (CEM II) and VDZ 300 (CEM III) provide traceable benchmarks for X-ray diffraction (XRD) methods, enabling consistent quantification of crystalline phases and amorphous components across laboratories and instruments. Rapid, reliable XRD workflows reduce production variability, speed corrective actions, and support product performance in construction applications.

Objectives and study overview

The application note evaluates the performance of the Thermo Scientific ARL X’TRA Companion X-ray Diffractometer for quantitative phase analysis of three cement SRMs (VDZ 100, 200, 300). Key objectives were to:

• Assess accuracy versus certified reference values for major crystalline phases and amorphous fractions.
• Evaluate reproducibility (estimated standard deviations) across repeated measurements.
• Compare short measurement times (5, 10, 20 minutes) to determine minimum scan duration meeting industry precision requirements.

Methodology

The experimental workflow comprised:

• Sample preparation: SRM powders manually pressed into top-loading sample cups and measured in reflection geometry with sample spinning.
• Radiation and measurement: Cu Kalpha radiation (1.541874 Å); standard measurement durations tested were 5, 10 and 20 minutes. For reproducibility assessment, 11 consecutive runs were performed for each time on VDZ 100; single 10-minute runs were used for VDZ 200 and VDZ 300 accuracy checks.
• Data analysis: Rietveld refinements were performed using Profex software. Amorphous (or poorly crystalline) contents—notably blast-furnace slag in CEM II/III—were quantified using the PONKCS (partial or no known crystal structure) method.

Used instrumentation

• Thermo Scientific ARL X’TRA Companion X-ray Diffractometer.
• Cu Kalpha X-ray source (lambda = 1.541874 Å).
• Profex software for Rietveld refinement.
• PONKCS approach for amorphous phase quantification.

Main results and discussion

Key findings from the Rietveld analyses and comparison to VDZ certified values:

• VDZ 100 (CEM I): Total alite (C3S tot) was measured ~58.7–59.4 wt% across scan times and matched the certified value (~59 wt%) within expected deviations. Individual polymorphs (C3S M1 and M3) were resolved; precision (ESD) improved when extending measurement time from 5 to 20 minutes. Minor phases (C4AF, C2S beta, C3A components, gypsum, carbonates) were quantified with 1s reproducibilities typically ≤0.5–1.0 wt% depending on phase abundance.
• VDZ 200 (CEM II): The measured slag (amorphous) fraction was ~20.3 wt%, consistent with the certified ~20.1 wt% when using PONKCS. Major clinker phases (C3S tot ~37.9 wt%, C2S beta ~15.3 wt%) and minor constituents showed good agreement with reference values; deviations were small and within expected certification tolerances.
• VDZ 300 (CEM III): Slag-dominated composition was confirmed with slag ~70 wt%, matching the certified 70.4 wt%. Crystalline clinker components were minor and quantified with acceptable accuracy; amorphous quantification using PONKCS produced values within certified uncertainty.
• Reproducibility and speed: Even 5-minute measurements delivered precision that meets industry guidelines such as ASTM C1365 and typical industrial QC criteria for many phases. Increasing scan time improved estimated standard deviations, as expected, but the 10-minute protocol offered a practical compromise of speed and precision for routine QC.

Benefits and practical applications

The evaluated workflow demonstrates practical advantages for industrial and research laboratories:

• Fast throughput: Reliable results achievable in as little as 5–10 minutes, enabling higher sample throughput for production QC.
• Traceable accuracy: Agreement with certified SRM values supports instrument benchmarking and method validation.
• Comprehensive phase coverage: Capability to quantify multiple clinker polymorphs, hydration-related sulfates, carbonates, and amorphous supplementary materials like slag.
• Fit-for-purpose amorphous quantification: PONKCS integration allows robust estimation of non-crystalline fractions critical for blended cements.

Future trends and potential applications

Anticipated developments and opportunities include:

• Further automation of sample handling and data-reduction pipelines to increase throughput and reduce operator variability.
• Integration of advanced detectors and faster optics to shorten measurement times while preserving or improving precision.
• Improved amorphous-phase models and expanded SRMs to cover a wider range of blended cements and industrial by-products.
• Use of machine learning for peak deconvolution, polymorph discrimination, and rapid anomaly detection in production environments.
• Adoption of in-line or at-line XRD systems for real-time process monitoring and closed-loop process control in cement plants.

Conclusion

The ARL X’TRA Companion X-ray Diffractometer combined with Rietveld refinement (Profex) and PONKCS amorphous modeling provides accurate and reproducible quantitative phase analysis of cement SRMs VDZ 100, 200 and 300. Results are within certified uncertainties and meet industry precision standards even at short measurement times, supporting rapid QC workflows in cement production and research settings. Extending measurement time improves precision, but a 10-minute protocol offers an effective balance for routine use.

References

1. Döbelin N., Kleeberg R., Rietveld refinement in Profex: J. Appl. Crystallogr. 2015, 48, 1573–1580.
2. Scarlett NVY., Madsen IC., The PONKCS method for amorphous quantification: Powder Diffraction, 2006, 21(4), 278–284.