Quantitative phase analysis of anhydrous Portland cement via combined X-ray diffraction and Raman imaging: Synergy and impact of analysis parameters

Quantitative phase analysis of cementitious materials is crucial for understanding and predicting their performance. For anhydrous Portland cements, a variety of techniques based on microscopy, spectroscopy, and diffraction exist. Here, we employ two highly diverse techniques (X-ray Diffraction and Raman Imaging) to a common sample (ASTM Type I/II OPC). We find that, firstly, the two methods are highly complementary in the initial phase identification, given that certain clinker phases are difficult to detect in one as opposed to the other. Secondly, quantitative analysis can be influenced by parameters such as preferred orientation, order of phase addition, and the nature of the binarization algorithm. Specific signal-to-noise (SNT = 5) and epoxy-to-signal (EST = 10) thresholds resulted in the highest alignment between the two methods (R² > 0.99, Δwt% < 2.5 %). Thirdly, Raman imaging area can be reliably reduced (25 mm² to 9 mm²) to shorten scan time by 2.5× (8 h to 3 h).