Management and characterization of MSWI residues

The aim of this study was to assess the feasibility of concrete production using slags and exhausted sand from municipal solid wastes incineration plants. These solid residues were produced from a fluidized bed incineration plant treating refuse derived fuel (RDF) from municipal solid wastes. The two raw wastes (slag and sand) were characterized in order to study their chemical composition and their leaching behaviour according to the 16 days leaching test (Ministerial Decree 05/02/08). The results show that both in slag and in sand there are high concentrations of copper, lead, chromium and zinc; therefore copper, cadmium, chromium, arsenic and selenium in the leachate are higher than the maximum law concentration. The two wastes were reused as a “recycled aggregate” for cement mixtures production, in substitution of natural aggregate (with dosage of 200, 400 and 600 kg/m3). These concrete mixtures, after curing (7, 28 and 60 days), were characterized with conventional physical-mechanical compression tests. The mechanical characteristics were very low for concrete with 300 kg/m3 of 32.5R Portland cement that is classified as not structural concrete according to UNI EN 206-1/2001; otherwise, the mechanical characteristics were improved in concrete containing 300 kg/m3 of 42.5R Portland cement and 400 kg(waste)/m3 (concrete), that was classified as ordinary concrete (class C16/20), with mechanical compressive strength higher than 20 MPa after 28 days of curing.