Municipal Solid‐Waste Incinerator Fly Ash for Geotechnical Applications

Abstract

Many highly urbanized cities are faced with the problem of disposal of municipal solid waste because of the scarcity of land available for landfilling. One possible solution is the incineration of the municipal solid waste. After incineration, about 20% by weight of fly ash and other residues are produced. Investigations into the physical and engineering properties of the fly ash derived from municipal solid‐waste incineration indicate that the material is a potential source of fill material, with low compacted density and high strength. The fly ash was relatively free draining, with permeability of the same order of magnitude as coarse grained materials. The use of the fly ash as an admixture in the stabilization of a soft marine clay showed improved undrained shear strengths and lower compressive properties. Leachate tests on the samples of fly ash initially indicated trace quantities of cadmium and chromium in excess of the acceptable drinking‐water limits. After leaching for 28 days, the concentrations fell below the drinking‐water limits. Lime and cement can be used to stabilize the fly ash. The concentrations of heavy metals in the leachates of lime and cement treated fly ash were nondetectable.