Alkali activation of kaolinite for production of bricks and tiles

New low cost building materials were developed by alkali activation of Jordanian Hiswa kaolinite. The optimum amount of NaOH, water and added sand were determined. Physical, thermal, mineralogical and microstructural properties were investigated. A compressive strength of 32 MPa was obtained for a geopolymer mixture cured at 80 °C for 24 hours. The petrography results indicate that the geopolymerization process has increased the compaction and decreased the porosity. The mineralogical and microstructural results on the hardened geopolymer indicate the formation of sodium zeolite phases and feldspathoids. The high compressive strength is directly related to the formation of the new phases that fill the pore spaces and bind the matrix.