Unlike coal fly ash, fly ash of heavy fuel oil has receivedmuch less attention in the literature. In thiswork, detailed
physicochemical characterization of heavy fuel oil fly ash (FA) is provided. The ash has a carbonaceousmatrix and
contains V, Ni, Zn, Cr, Cu, and Pb with variable amounts. V was the most abundant heavymetalwith enrichment
factor of 277 in the FA. The presence of V in the FA is attributed to the formation of Mg3V2O8 oxides at high combustion
temperature as confirmed by XRD. Particle size distribution showed that the mean particle diameter of
the FA was 70.5 μm. Extraction recovery up to 85% of metals was achieved using 1.0 M HNO3 and at room temperature.
Standard metal-leaching tests confirmed that the elution of the toxic metals and the level of eluted Zn
were much higher than the regulated value for the solid residues. Five stable geopolymers GPs containing 41.7
wt.% FA were prepared. All GPs showed high compressive strength and low water absorption which support
their application as lightweight construction composites. Most importantly, adding FA to GP had significantly reduced
metal migration into the environment as confirmed by the synthetic precipitation leaching procedure.