This study addresses critical limitations in conventional mineral admixture characterization methods—namely insufficient qualitative analysis, cumbersome quantitative procedures, and lack of structural information—by applying the well-established X-ray diffraction (XRD) Rietveld full-pattern fitting approach. The methodology, though mature in XRD analysis, is innovatively applied to mineral admixtures to enable simultaneous qualitative identification, quantitative analysis, and crystal structure refinement of multiphase systems. Simultaneously, it serves as a practical reference for the application of Rietveld refinement in the phase analysis of mineral admixtures and similar inorganic materials in engineering scenarios. Validation was performed using simulated samples (1–6) with predefined crystalline/amorphous compositions and a real-world highway construction admixture (7). Key findings demonstrate high precision for multiphase crystalline systems, with absolute errors < ±3% and Rietveld agreement indices (Rwp < 4.76%, S ≤ 1.55) confirming reliability; effective differentiation of polymorphs (e.g., anatase versus rutile TiO2), overcoming limitations of chemical analysis; robust quantification of amorphous content (e.g., SiO2) via internal standardization, though with higher variability (RSD ≤ 4.86%) due to diffuse scattering; minimal refinement deviations in structural parameters (lattice constants Δ < 0.001 nm, atomic positions Δ < 0.004) versus reference data. A practical mineral admixture (five phases including SiO2/SnO2) was successfully analyzed with reliable fitting quality (Rwp = 6.74%, S = 1.72), meeting the general reliability criteria for multiphase sample analysis (Rwp < 10%, S = 1.0–2.0) and confirming the method’s strong applicability in engineering practice. The framework provides a foundation for evaluating admixture quality, elucidating concrete performance mechanisms, and designing advanced cementitious materials, while offering broader applications in inorganic phase analysis.
Yang et al. (Fri,) studied this question.