Characteristics of residual oil fly ash and their utility for construction purposes

The present work investigates the physical and chemical characteristics of the residual oil fly ash, generated as a by-product or industrial waste from burning heavy fuel oil in power plants. A possibility of re-utilization of the residual oil fly ash for construction purposes was estimated by activation of the residual oil fly ash with cementitious cementious materials as a hardened paste matrix. The physical properties of the residual oil fly ash showed low bulk density, 0.21 g/cm3 and water content, 0.33%, as compared with literature. The particle size less than 120 ?m. The chemical analysis showed that the residual oil fly ash composes mostly of carbon, about 69% with 7 % sulfur and residue ash. In addition, to significant amount of some heavy metals, such as Sr, Ti, Zn, V, Cr and Ni are detected. The XRD data confirm that it residual oil fly ash is mainly composed of amorphous carbon with metallic sulfates and metallic oxide materials. In order to investigate the changes of the hardened paste strength when the residual oil fly ash is added, the reference mixture without residual oil fly ash was is performed. Also, the changes of the density was is estimated. The results indicated that the addition of 10, 20, and 30 wt.% of residual oil fly ash shows a remarkable decrease in both; strength and density. This study has found that, the residual oil fly ash has the potential to be re-utilized with cementitious cementious material as light weight material, or a black pigment, which provides a good change in color and density properties.