Abstract: The slag， which is used with garbage incineration fly ash and desulfurization gypsum in the composition of cementitious material， replaces cement in whole or in part. The solidification effect of the cementitious materials on heavy metals from waste incineration fly ash was studied with the change of slag content. The results showed that compressive strength of the paste block first increases and then decreases with the increasing of the slag content. When the paste block is made of fly ash 20%， slag 70% and desulphurization gypsum 10%， compressive strength of the paste reaches 47 MPa for 28 days maintenance in the temperature of 35 ℃ and the humidity of 95%. The heavy metal irons leaching concentration of Cr， Cd， Cu， Hg， Pb and Zn were all lower than the standard of drinking water. The solidification effect of Pb and Cr is better than that of cement cementitious system. The detection results of XRD and FT-IR indicated that the major hydration products of slag-based cementitious materials are ettringite， C-S-H gel and hydrocalumite， which show good encapsulation effect on heavy metal ions. Compared with cement gelled system， slag-based cementitious material system has obvious superiority in curing heavy metals irons from garbage incineration fly ash.

Key words: Garbage incineration fly ash, Slag-based cementitious materials, Cement, Heavy metal ions, Compressive strength