Investigation on Impacts of Municipal Solid Waste Incineration Bottom Ash on Cement Hydration

The goal of this study is to explore beneficial use of municipal solid waste incineration (MSWI) bottom ash in cement-based products for saving waste-disposal cost, conserving natural resources, and saving energy. However, uncertain engineering characterization of this waste product has been always a major concern; thus, particularly in the United States, there has been no recycling of MSWI bottom ash. In this study, efforts were made to characterize MSWI bottom ash and to evaluate the effects of the ash as a partial replacement of cement and fine aggregate in cement paste and concrete, respectively. This paper presents and discusses: 1) physical and chemical properties of MSWI bottom ash; 2) its effect on cement hydration; and 3) physical and mechanical properties of cement paste and concrete specimens containing bottom ash. The main focus of the investigation particularly was on the impact of MSWI bottom ash on cement hydration. It was found that MSWI bottom ash causes both a hydration effect due to existing calcium oxide, calcium sulfate, and silica dioxide, as well as volume expansion due to hydrogen gas evolution.