Porous glass-ceramics made from microwave vitrified municipal solid waste incinerator bottom ash

Global warming and depletion of resources have fueled research towards innovative building materials of low environmental impact and high performance engineering properties. Porous glass-ceramics were synthesized using municipal solid waste incinerator (MSWI) bottom ash (BA) as a starting material. BA was initially milled and then vitrified, as a purification step, by direct microwave heating, characterized by a high glass yield. Highly porous glass-ceramics were produced by intensive mechanical stirring of vitrified bottom ash (VBA) aqueous suspensions under weak alkali activation (1 M NaOH and 2.5 M NaOH) and sinter-crystallization at 800 °C or 900 °C. The obtained glass ceramics, with up to 70 vol% porosity, exhibited compressive strength well above 1 MPa, being comparable to lightweight construction materials, such as aerated concrete. High relative permittivity was measured for the 10 wt% soda-lime glass doped porous VBA material sintered at 800 °C, paving the way for its use as a potential semiconductor catalyst.