Characteristics of MSW Incinerator Ash for Use in Concrete

The incinerator ash, the fine residue resulting from the burning of municipal solid waste (MSW), has been characterized with a view to utilizing the material to replace part of the Portland cement normally used for making concrete. Characterization involved chemical and particle size analysis, observation under the scanning electron microscope (SEM), thermal analysis (TG/DTA) both in air and argon, and XRD analysis. Leaching tests in neutral and acid media were also run to assess whether this material is likely to release heavy metals into the environment. Blended cements were prepared by mixing a Portland cement with various amounts of ash. Mortars made of samples of Portland and blended cements were tested to ascertain compressive and flexural strength. It ensues from consideration of the chemical and physical characteristics of the ash, as well as the mechanical properties of the mortars produced, that after preliminary washing and/or grinding the material could, in fact, be used as partial replacement for Portland cement, although there is some slight reduction in the mechanical properties of the product.