Application of Fourier transform infrared spectroscopy in cement Alkali quantification: Fid-Bau Portal

Application of Fourier transform infrared spectroscopy in cement Alkali quantification

Nasrazadani, S. / Springfield, T.

Abstract Alkali in cement is responsible for the Alkali–silica-reaction phenomenon that manifests itself in the form of premature cracking in concrete structures such as bridge decks and concrete pavements. X-ray fluorescence spectroscopy (XRF) is commonly used for cement Alkali quantification but a simpler and faster analytical procedure based on Fourier transform infrared spectroscopy (FTIR) has been expanded for this purpose. An analytical absorption band at 750 $ cm^{−1} $ in the FTIR spectra of cement samples belonging to Alkali solid solution of tricalcium aluminate [$ C_{3} $A(ss)] is used for Alkali quantification. Regression analysis of a plot correlating FTIR absorption band area ratio (750/923 $ cm^{−1} $) to equivalent Alkali $ Na_{2} $$ O_{e} $ ($ Na_{2} $$ O_{e} $ = % $ Na_{2} $O + 0.658 × % $ K_{2} $O) measured by XRF shows a linear correlation coefficient, R2, of 0.97. High Alkali cement samples show a higher microstructural disorder coefficient, Cd, which is a reactivity criterion introduced by Bachiorrini and co-authors (Proceedings of the seventh international conference on concrete alkali-aggregate reactions‚ 1986) for ASR-susceptible aggregates. Results of this research indicate applicability of FTIR technique to quantitatively predict cement vulnerability to ASR through the $$ A_{{750\,{\text{cm}}^{ - 1} }} $$ to $$ A_{{923\,{\text{cm}}^{ - 1} }} $$ band area ratio and the magnitude of the disorder coefficient (Cd).