Characterization of bottom ash in municipal solid waste incinerators for its use in road base.

Incineration of municipal solid wastes (MSWs) produces by-products which can be broadly classified as bottom and fly ashes. Since MSW incineration started, possibilities other than landfilling the incineration residues have been sought; most initiatives in this sense tend to use these residues as aggregate substitute in pavements and other road construction elements. The main goal of the present work is the physical and chemical characterization of the local incineration bottom ash towards its eventual re-utilization. The study includes not only the specific aspects regarding its role as pavement element, but also the assessment of the environmental effects. Therefore, together with the determination of physical (moisture content, apparent and bulk densities, crystallinity, etc.) and engineering properties (particle size distribution, abrasion and impact resistance, etc.), full chemical characterization of the bottom ash and the study of leaching as a function of aging time have been undertaken. The results obtained indicate that the metal content of both the raw bottom ash and its leachates fulfill the environmental regulations provided that the bottom ash is stored for at least one month. Engineering properties of the bottom ash are close to those of natural aggregates and, thus, road-construction use of these residues seems to be feasible.