Sustainable Treatment of Dredged Sediments Using Waste-Based Binders: Fly Ash and Eggshell Lime

To maintain sufficient depth in reservoirs, ports, and harbors, sedi-ments are dredged worldwide. However, these dredged sediments are highly compressible with poor mechanical characteristics and are often contaminated, thereby stabilized or solidified by using cement and lime. However, their pro-duction consumes natural resources along with high CO2 emissions. In the pre-sent note, the use of alternative binders in the treatment of dredged sediments is evaluated. Sediments collected from Ancona confined disposal facilities were characterized for grain size distribution and contaminants’ concentration and treated with 2, 4, and 8% of fly ash and lime produced from eggshells. Subse-quently, settling column tests, batch leaching tests, and microstructural investi-gation were carried out. The results demonstrated that sediments treated with an 8% binder composition exhibited flocculated structures and the formation of calcium silicate hydrates, rendering it a promising mix. In addition, no leaching of contaminants was observed, and further testing with extended contact time is required to draw definitive conclusions about the solidification capabilities of the tested mixtures. The preliminary