Life cycle assessment to optimize alkali-activation of glass waste for sustainable construction materials

This study investigates the valorisation of boro-alumino-silicate glass waste through alkali activation, proposing its reuse in the production of lightweight construction materials. The research aims to evaluate the environmental impacts of three different processing: (A) conventional cold consolidation at 40 °C for seven days, (B) a hybrid process involving 24-h pre-curing at 40 °C followed by microwave treatment (450 W, 5 min), and (C) an accelerated process involving 6-h pre-curing at 75 °C followed by the same microwave treatment. A gate-to-gate Life Cycle Assessment (LCA) was conducted using ReCiPe 2016 Midpoint (E) method to quantify environmental performance. The functional unit was defined as 1 kg of glass to produce consolidated material. Results indicate substantial differences among the processes: process A exhibited the highest overall environmental burden (77.9 kg CO₂ eq), while process B (11.2 kg CO₂ eq) and process C (2.9 kg CO₂ eq) showed significant reductions. Contribution analysis identified the consolidation phase as the dominant contributor to impacts, driven by electricity consumption and uncertainty analysis confirmed the robustness of the results. Monte Carlo uncertainty analysis confirmed the robustness of the results, with process C consistently emerging as a sustainable option. The study highlights the potential of integrating mild alkali activation and microwave technology as a circular and energy-efficient strategy for the valorisation of pharmaceutical glass within the framework of sustainable material design.