MICROSTRUCTURAL ANALYSIS OF OPC SILICA FUME NA-BENTONITE INTERACTIONSIN CEMENT-BASED SOLIDIFICATION OF ORGANIC-CONTAMINATED HAZARDOUS-WASTE

As one of major deficiencies in cement-based waste stabilization/solid ification (S/S) processes is their difficulty in treating inorganic wa stes containing organic material, silica-fume and Na-bentonite are stu died as potential pozzolanic reagent and pre-solidification adsorbent of organic components. This paper presents microstructural studies of interactions between silica fume, Na-bentonite, containing adsorbed or ganically contaminated harzardous wastes, and a cement matrix. The sca nning electron microscopy/ energy dispersive spectroscopy (SEM/EDS) an alysis of the waste/OPC mix showed that the ettringite crystals were i n needle shape deposited in the voids or on the surface of hydration m aterial. Microstructural studies of solidified wastes with silica fume and/or Na-bentonite showed that their presence caused an inhibition t o the ettringite formation. The results indicated that the incorporati on of silica fume and/or Na-bentonite into the cement matrix minimized the detrimental effects of organic materials on the cement hydration reaction.