PROPERTIES OF FLY-ASH BRICKS PRODUCED FOR ENVIRONMENTAL APPLICATIONS

The effects of pressure and temperature on preparation of bricks made from fly ash have been investigated. Bricks from Texas lignite fly ash and fly ash-clay (kaolinite or montmorillonite) mixtures were prepared. It has been found that bricks with 20% kaolinite and 5% montmorillonite have green strengths high enough to handle without any additives. Samples were pressed under the pressure ranging from 35 MPa to 350 MPa. Lamination occurred at pressures higher than 270 MPa and plerospheres cracked under applied pressure. Fly ash with and without clay pellets were fired at 1000 degrees C for 3 hours. Surface and bulk properties of fired and unfired samples were investigated and devitrification/sintering processes analyzed by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and x-ray photoelectron spectroscopy (XPS) techniques and the results are reported.