INVESTIGATING THE POSSIBILITY OF UTILIZING LOW KAOLINITIC CLAYS IN PRODUCTION OF GEOPOLYMER BRICKS

Low kaolinitic clays raw materials were chemically and mineralogically characterized. The manufacture of geopolymer bricks based on thermally treated clays (700 degrees C for 2 hours) and NaOH solution or alkaline sodium silicate solutions were investigated. The activation process was conducted at different temperatures (room temperature, 75 degrees C and 150 degrees C). The phases formed were studied by X-ray diffraction analysis and scanning electron microscopy. The amorphous geopolymer phase was formed at all processing temperatures. The mechanical properties depended on amounts of active aluminum silicates in the starting material, the type of activator and the processing temperature. The results showed that two of the studied clays have adequate characteristics for geopolymer brick manufacture when activated with NaOH solution. However, all studied clays were suitable for geopolymer brick manufacture if activated with sodium silicate solution. Geopolymer bricks with low production costs and low production technology could be produced from clays deposits in Saudi Arabia.