A common perception concerning glass is its infinite recyclability. However, recycling in strict sense, with cullet used as feedstock for the original articles (“closed-loop recycling”), is not straightforward. A fundamental limiting factor is the difficulty in the separation of glass from heterogeneities. Contaminants lead to defects, such as stones and streaks, or deviations from the original chemical composition. This symposium is open to the widest expressions of circular economy applied to glass. Closed-loop recycling may be improved, as an example, by new equipment and logistic strategies. The manufacturing of new glass-based construction materials (“open-loop recycling”), such as glass foams, glass-ceramics, alkali-activated materials (geopolymers), may represent a valid alternative, if providing adequate revenues to compensate for new thermal treatments and/or additives.