EFFECT OF RH ON CARBONATION OF HARDENED CEMENT PASTE PARTICLES UNDER GENERAL ATOMOSPHERIC CO₂ CONCENTRATION STUDIED BY FTIR SPECTROSCOPY

Abstract

An understanding of carbonation reactions is needed to accurately assess the amount of carbon dioxide fixed within cement structures. In this study, the carbonation reaction on the surface of hardened cement paste under atmospheric carbon dioxide concentrations was investigated using infrared spectroscopy （FTIR） with humidity as a variable. By integrating the peak intensities obtained, we were able to semi-quantitatively analyze the change over time of each component and approximate logarithmically the formation rate of calcium carbonate and the decomposition rate of calcium hydroxide at the powder surface. In addition, the decalcification and polymerization reactions of the C-S-H gel could be seen from the shifts in the peak wavenumbers. Furthermore, the humidity dependence of the precipitated polymorph of the calcium carbonate was also determined.