Recycling of pre-stabilized municipal waste incinerator fly ash and soda-lime glass into sintered glass-ceramics

A recent method, based on the use of amorphous silica, allows for the inertization of MSWI fly ash, avoiding expensive vitrification. The present paper demonstrates that glass-ceramics, i.e. the most established products from waste-derived glasses, are feasible by direct, inexpensive viscous flow sintering of pre-stabilized fly ash mixed with clay and recycled soda-lime glass. The sintering treatment did not compromise the chemical stabilization of fly ash, as confirmed by leaching test and by cell culture studies (with mouse embryonic fibroblasts used to assess possible cytotoxicity), applied on sintered glass-ceramics. Optimized glass-ceramic tiles, processed at 1050 °C for 30 min, not only featured attractive aesthetic appearance and low water absorption (<2%), but also exhibited a remarkable specific strength (∼3.6 MPa0.5 cm3/g).