Infrared spectra experimental analyses on alkali-activated fly ash-based binders.

One of the most used characterization techniques in the field of alkaline activated cements studies is infrared spectroscopy. Its prominence lies in that it allows characterizing mixtures during the alkaline activation by providing information about the vibrations of the chemical bonds in the molecular units, both of amorphous and crystalline products. This research paper is aimed at examining the influence of the concentration of calcium hydroxide (CH), sodium hydroxide (SH), temperature and curing time on the structure of alkaline activated cements, based on coal fly ash, from the deconvolution of the infrared spectrum between 4000 and 400 cm ^-1 . 9 mixtures were analyzed by infrared spectroscopy at 3 and 28 days after curing, based on a surface's response experimental design by varying the amount of SH (5.17-10.83 M), CH (2.93-17.07% ash's wt.) and the curing temperature (25, 35 and 45 °C). The results show significant variations in the frequency and area of the deconvolved bands in the functional groups: O-H (2600-3800 cm ^-1 ), C-O (1580 and 1350 cm ^-1 ) and T-O (T: Si (Al), 1300-400 cm ^-1 ). Such variations are due to the reorganization of the forming elements (present in the ash) network and modifiers (present in CH and SH) for the formation of cementing gels C-(A) -S-H (970 cm ^-1 ) and N-A-S-H (1009 cm ^-1 ).
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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