Characterization of Portland cements by X‐ray spectrometry allied to chemometrics

This work reports the use of X‐ray spectrometry (XRS) allied to chemometric techniques to easily distinguish types of Portland cements, as well as to quantify some of their constituent elements. The samples were irradiated as powders for 200 s using two distinct irradiation conditions, one more adequate for heavier elements (condition 1) and the other (condition 2) for lighter elements, using a conventional bench top energy dispersive X‐ray fluorescence (EDXRF) equipment. The spectra were processed via the software The Unscrambler, version 9.2. The PLS 1 LV1 × LV2 scores graph shows a classification into five groups, in accordance with the calcium concentration, using condition 2. The classification of the cements by producer was feasible using the PLS1 LV1 × LV3 scores graph, with condition 1. The elements Ca, Si, Al and Mg were successfully quantified using multivariate calibration of the whole spectra. However, for Fe, S and K, better results were obtained by correlating their corresponding Kα peaks with concentrations in a univariate procedure, using irradiation condition 2. Chemometric tools allied to XRS are powerful techniques to classify Portland cements, regarding to their origins and their calcium concentration, which is related to the cement type. The PLS chemometric tool was very useful to easily quantify light elements, such as Al, Si and Mg, a challenge in most X‐ray analytical methods, since their Kα emission peaks are very close to each other.