Production and characterization of lightweight aggregates from municipal solid waste incineration fly-ash through single- and double-step pelletization process

The performance of a cold-bonding pelletization process was investigated for lightweight aggregates (LWAs) production from municipal solid waste incineration (MSWI) fly-ash (FA), by including multiple materials in the aggregate mixture. Before pelletization, FA pre-treated washing with water, which led to reduction chloride (66.79%) and sulphate (25.30%) content. This further confirmed XRF XRD analyses, showed elements content chlorine crystalline phases. carried out using both single- double-step methods. For single-step all mixtures contained 80% FA, combined various compositions cement (5, 10, 15%) granulated blast furnace slag (GBFS) 15%). 30% 70% marble sludge (MS) were added each previous mixtures. apparent density varied between 1.60 1.87 g cm−3, suggesting their suitability be classified as LWAs. Aggregates produced improved characteristics, water absorption capacity open porosity generally lower compared corresponding pelletization. best values compressive (crushing) strength (almost 11 MPa) observed initial cement: GBFS mixture 15%:5%. Results leaching tests an overall significant release sulphate. Nevertheless, reduced 1.73-4.02 times 1.58-5.67 sulphate, that better performances are achievable through addition second layer.