Determination of Polymer in Dry-Mixed Mortar by IR Combined with PLS Regression Method

A series of standard samples of dry-mixed mortar with different and known available contents of polymer were prepared by sampling of the mortar components from various producers with various models and by variation of ratio of cement and sand and mixing of additives. Twenty samples of the mortar with unknown polymer contents and eighty samples of the standard samples of mortar prepared above were taken and analyzed by ATR-FTIR spectrometry to obtain the IR-spectra of the polymer and corrected by applying the chemometric method of PLS regression. The methods of continuous wavelent transform, Savitzky-Golay smoothing and differentiation were applied to pretreat the IR-spectra signals, to raise the precision of the established model. The method of signal smoothing gave the most effective result. After optimization with the method of MC-UVE, values of mean square deviations of the measurements of the samples of the calibration set and the testing set were reduced from 0.213 and 0.217 to 0.170 and 0.180 respectively. The correlation coefficient of data of the testing set found was 0.991. Good correlationship was obtained between data obtained by the proposed method and the national standard method.