The performance characteristics of cement are directly related to its phase composition. For example, ASTM type III cement develops high early strength and is characterized by having a larger mass fraction of alite. In comparison, ASTM type IV cement is known to have a low heat of hydration and is characterized by having a much lower mass fraction of alite. Therefore, having prior knowledge of the phases in a cement mixture and their relative amounts allows one to have control over the physical characteristics of the final product.
Traditionally used methods of phase composition analysis include microscopy, chemical analysis, and the Bogue calculation. However, none of these methods allow for rapid and accurate multi-phase identification and quantification of a sample. X-ray powder diffraction is the only direct method for qualitative and quantitative multi-phase analysis of a cement sample.
Portland cement is composed of four major phases — alite (C3S), belite (C2S), ferrite (C4AF), and aluminate (C3A) — in addition to several other potential minor components such as gypsum, free lime, periclase, arcanite, etc. Each phase/mineral in the sample produces its own characteristic diffraction pattern with the intensity of each pattern being proportional to the relative amount in the sample. In combination with powerful powder diffraction software, one can easily identify the phases within a complex mixture and quantify their amounts.
Through the use of our economical AXRD Benchtop unit coupled with the proper software, one can perform quantitative phase analysis using whole pattern fitting and Rietveld refinement to determine the composition of various types of raw feed materials to ensure optimal properties of the produced final product.
