Sintering mechanisms, phase transformations and microstructure of porcelain stoneware containing thermally inertized man-made vitreous fibres

The waste incorporation into porcelain stoneware is a key strategy for enhancing sustainability in ceramic production. To achieve a satisfactory finished product, a crucial aspect to be investigated is the effect that a waste can induce on the tile sintering behaviour, which, in turn, determines its final technological properties. This study investigates the effect of a glass deriving from the thermal inertization of man‑made vitreous fibres on the sintering of porcelain stoneware tiles, obtained by pressing and fast firing. Results indicated that it is easier to incorporate into porcelain stoneware than other peralkaline glasses, due to its tendency to crystallize in the early stage of the densification process, limiting the interaction with the ceramic matrix and allowing the achievement of a good densification. Otherwise, the microstructure of the fired tiles in overfiring conditions is influenced, since the loss of bulk viscosity and likely the Fe3 + reduction led to bloating phenomena.