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 prepare d. It has been found that bricks with 20% kaolinite and 5% montmorillo nite have green strengths high enough to handle without any additives. Samples were pressed under the pressure ranging from 35 MPa to 350 MP a. Lamination occurred at pressures higher than 270 MPa and plerospher es cracked under applied pressure. Fly ash with and without clay pelle ts were fired at 1000 degrees C for 3 hours. Surface and bulk properti es of fired and unfired samples were investigated and devitrification/ sintering processes analyzed by x-ray diffraction (XRD), Fourier trans form infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and x-ray photoelectron spectrosco py (XPS) techniques and the results are reported.