Activating process of geopolymer source material: Kaolinite

The calcining process was recorded by differential scanning calorimetry and thermogravimetry (DSC-TG). The dehydroxylation (activating process) was partitioned into two steps by calculating and comparing the O—H bond lengths between inner hydroxyl group and surface hydroxyl group, as well as the ionic bond of Al—OH and position of —OH. X-ray diffraction (XRD) and compressive strength measurement show that the activity of calcined materials increases with the increasing of temperature in dehydroxylation region but decreases abruptly in the “spinel” region. The suggested temperature for activating kaolinite is 900 °C. Funded by the National High-Tech Research and Development Program of China(No. 2006AA06Z225)