Application of Fourier Transform infrared spectroscopy (FTIR) coupled with multivariate regression for calcium carbonate (CaCO3) quantification in cement

• The carbonation process of cement with supercritical CO 2 was reevaluated. • Fast, low-cost, and reliable models were obtained to quantify CaCO 3 in cement by FTIR. • The effect of CO 2 on the cement matrix must be considered for the development of PLS. • The cement fractions relevant to the PLS regression are portlandite, CaCO 3 and C-S-H. • The PLS model showed a good correlation coefficient and a low CaCO 3 prediction error. Partial least squares (PLS) regression models were developed to quantify CaCO 3 in cement and to study the CO 2 effect on the material matrix. PLS results presented good correlation coefficient (R 2 = 0.9995) and low estimation error (RMSEP = 3.61 mg CaCO 3 /g cement). From the results, it was observed that the portlandite consumption, the increase in CaCO 3 content and the C-S-H decalcification-polymerization are the most relevant cement chemical transformations. Thus, it was concluded that: i ) it is possible to obtain fast, low-cost, and reliable models to quantify CaCO 3 by FTIR and ii ) the method is applicable to study carbonated cement-based materials.