Fourier Transform Infrared Spectroscopic Analysis of Kaolin and Metakaolin used in Geopolymer Production

Abstract

Characterizations of Kaolin and metakaolin samples obtained by the thermal treatment of raw clay at 650 ºC were carried out using Fourier Transform Infrared spectrophotometer. This enabled the investigation of the influence of curing conditions on the mechanical properties and microstructures of the geopolymers. Results of Kaolin samples gave characteristic peaks at 3682 cm-1as OH stretching vibration, 2783–2106 cm-1 as organic impurities, 1084 cm-1 as Si-O-Si or Al-O-Si asymmetric stretch and 769.9 cm-1 as Al-O-Si inner surface vibration. Characteristic peaks obtained for metakaolin are 3592 cm-1 as OH stretch vibration, 2934–2206 cm-1 as organic impurities, 1845 cm-1 as H-O-H bending of water and 887cm-1 as Si-O and Al-O asymmetric stretch vibration. The metakaolin was used to produce geopolymers at 28 days cure which gave characteristic peaks at 3625 cm-1 as OH stretch vibration, 1693 cm-1 as OH bending, 756 cm-1 as symmetric Si-O-Si or Si-O-Al and 1005 cm-1 as Si-O and Al-O asymmetric stretch. These results were comparable with those of previous studies and showed excellent properties for geopolymers .