Waste-derived glass-ceramics fired in nitrogen: Stabilization and functionalization

•Highly porous glass-ceramics obtained by direct foaming of alkali activated glass slurries.•Control of phase evolution by adjustment of firing temperature and atmosphere.•Firing in N2 promoted the stabilization of pollutants and novel functionalities.•Porous glass-ceramics fired at 1000 °C exhibited high dielectric permittivity.•Firing at 800 °C led to electrically conductive foams for electromagnetic shielding.