Upcycling of Boro-Alumino-Silicate Pharmaceutical Glass in Sustainable Construction Materials

Abstract

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 starting from 40 °C (‘cold consolidation’). Alkali are mostly expelled from the gel, according to the formation of water-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) and quartz sand as coarse aggregate. Moreover, industrial mud could be used instead of water in the preparation of alkaline solutions. Depending on the formulations, products comparable to facing bricks can be obtained directly after cold consolidation or after application of low temperature (700 °C) firing. In addition, selected formulations led to highly porous glass foams, to be used for thermal and acoustic insulation.