Cementitious Properties of Municipal Solid Waste Incineration Bottom Ash Aggregate

Abstract:

In order to research cementitious properties of municipal solid waste incineration bottom ash aggregate (BAA), hydraulic activity and pozzolanic activity of BAA were analyzed by strength test, and Xray fluorescence (XRF), Xray diffraction (XRD) and scanning electron microscope (SEM) were also used to study the microscopic mechanism. The results show that BAA consists of cement clinker mineral, active SiO2 and Al2O3. BAA has hydraulic activity and pozzolanic activity. Cement clinker minerals in BAA react with water to produce calcium silicate hydrate (CSH) gel and Ca(OH)2. Pozzolanic reaction occurs when active SiO2 and Al2O3 are activated by Ca(OH)2 to form hydration products like CSH gel and calcium silicoaluminate hydrate. When BAA mixes with water and cement, besides the reactions mentioned above, pozzolanic reaction also occurs when active Al2O3 is activated by sulfate to form ettringite. Pozzolanic reaction of BAA in cement delays to some extent. Wetprocessed BAA shows lower cementitious properties than dryprocessed BAA, and BAA with longer weathering time also has lower cementitious properties.