HYDRAULIC ACTIVITY OF SLAGS OBTAINED BY VITRIFICATION OF WASTES

Instead of landfilling municipal waste incineration bottom ash, it is possible to produce latent hydraulic materials for blended cements by a smelting process. The waste material is mixed with various amounts o f quicklime, calcium carbonate, alumina, calcium chloride, and iron ox ide: then it is smelted at about 1500 C (2732 F) and cooled to obtain a synthetic glassy slag. After being ground, this slag is activated by clinker and gypsum. In the present study, the results concerning two blended cements containing 47.5 and 76 percent synthetic slag, respect ively, are presented. The mechanical properties of these cements are c ompared to those of a blast furnace slag blended cement. The influence of the gypsum content on the strength of mortars is also studied. It is shown that the synthetic slags present sufficient hydraulic activit y and low heavy metal content. In some cases the performances are the same as those obtained with a ground granulated blast furnace slag.