Vitrification and sinter-crystallization of fly ash with glass cullet

Abstract

The synthesis of a new glass-ceramic obtained by sinter-crystallization has been investigated by using soda-lime-silicate glass waste and fly ashes from a coal power thermal station located in Andorra (Teruel, Spain). An original glass as frit with composition of 50wt% recycled soda-lime glass, 25wt% bottom ash, 15wt% fly ash and 10wt% CaCO3 has been melted. After sinter-crystallization at 850ºC, it has precipitated two main crystalline phases: sodium anorthite and the hedenbergite. The linear shrinkage is 1/3 of the value of conventional porcelainized stoneware and the water absorption of this glass-ceramic is similar to a conventional porcelainized stoneware tile (less than 1wt%), being the apparent density slightly higher than this type of tiles (2.6g/cm3 instead of 2.4g/cm3 ). Flexural strength is near twice than porcelainized stoneware (around 950kg/cm2 instead of 550kg/ cm2 ) (95MPa in the new glass- ceramic with respect to 55MPa for the above mentioned as reference material).