Upcycling of Pharmaceutical Glass in Sustainable Construction Materials

The present Covid-19 emergency has dramatically increased the demand for pharmaceutical containers and the amounts of related waste. This paper aims at presenting the upcycling of discarded pharmaceutical glass into various porous ceramics, starting from the activation of fine powders suspended in weakly alkaline solutions (2.5 M NaOH/KOH). The alkaline attack determines the gelation of glass suspensions, according to hydration of glass surfaces, followed by condensation at 70 °C (‘cold consolidation’). Alkali are mostly expelled from the gel, according to the formation of soluble hydrated carbonates. The mutual binding of activated powders was exploited for the encapsulation of waste-derived glass (from the plasma processing of municipal solid waste) as coarse aggregate. Finally, pharmaceutical glass was successfully activated with industrial by-products, such as basic slurries from the cutting and polishing of clay bricks. Depending on the formulations, the waste mixtures led to products similar to facing bricks directly after cold consolidation or after application of low temperature (800 °C) firing. In addition, selected formulations led to highly porous glass foams, to be used for thermal and acoustic insulation.