Amorphous determination in calcium sulfoaluminate materials by external and internal methods

Abstract

External standard methodology has been successfully applied to quantify the known amounts of amorphous component that are increasingly added to cement-related materials. The consistency and accuracy of the methodology were demonstrated by the R2 values of the least-square fits determined against weighed amorphous amounts, which were close to 1.0 in all the series. This method requires common laboratory X-ray powder diffractometers (knowing the equipment constant) and avoids the dilution/alteration of the sample. However, the obtained values may be biased due to poor particle statistics. On the other hand, internal standard analysis in transmission geometry is suitable to determine the absolute amorphous and crystalline non-quantified contents that are less biased owing to enhanced particle averaging statistics. This method is, however, experimentally tedious due to the addition of the internal standard and the sample loading in the X-ray diffraction sample holders which represent inherent drawbacks to follow amorphous evolutions.