Mechanical and leaching properties of cement solidified hospital solid waste incinerator fly ash

Abstract A fly ash coming from a hospital solid wastes incineration plant was solidified/stabilized in cementitious matrices. Owing to the high chloride, sulphate and alkali content and the low Si, AI and Fe values this fly ash cannot be used in the formulation of blended cement. The objectives of solidification stabilization treatment were therefore to reduce the leachability of the heavy metals present in this material so as to permit its disposal in a sanitary landfill requiring only a low degree of environmental protection. The mechanical properties and leaching behaviour of solidified products were investigated. Fly ash and Portland Cement mixtures in ratios varying between 0.25 and 1.5 were tested for unconfined compressive strength after curing in tap water at 20°C. Leaching tests were performed both on fly ash and solidified/stabilized products using an acetic acid standard leaching test and a modified version thereof (dynamic leaching test).