Geopolymer Technology with Recycled Glass Materials

Geopolymer technology harnesses the reaction between aluminosilicate sources and alkaline activators to produce inorganic binders that rival traditional Portland cement. Recent efforts have focused on the incorporation of recycled glass as a silica-rich component, transforming waste streams into high-value construction materials. Finely ground glass powder contributes reactive silica, enhancing network formation and mechanical performance while reducing reliance on virgin raw materials and lowering carbon emissions. Optimisation of activator composition—from sodium hydroxide to blends containing sodium silicate or sodium aluminate—governs the formation of key gel phases such as calcium-silicate-hydrate and sodium-alumino-silicate-hydrate. Materials can be tailored to achieve desired fresh properties, setting times and durability. Challenges remain in controlling efflorescence, mitigating chemical leaching and ensuring long-term stability under environmental exposure. Advances in microstructural characterisation, including nuclear magnetic resonance and infrared spectroscopy, have elucidated chain polymerisation and cross-linking density. Deployments span precast elements, mortars and concretes with improved acid resistance, mechanical strength and immobilisation of hazardous ions, underscoring the global significance of upcycling glass cullet towards a circular economy.

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Geopolymer Technology with Recycled Glass Materials publication trend

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Technical terms

Geopolymer: An inorganic polymer formed by the alkali-activation of aluminosilicate materials, yielding a three-dimensional network of Si–O–Al bonds.

Alkali activation: A chemical process in which a highly alkaline solution (e.g. sodium hydroxide, sodium silicate) dissolves aluminosilicate precursors to form geopolymer gels.

C(N)-A-S-H gel: A mixed calcium-alumino-silicate-hydrate phase that contributes to strength and reduces alkali leaching in geopolymer systems.

Efflorescence: The formation of salt deposits on the surface of geopolymers due to the migration and crystallisation of alkali species.

Glass powder: Finely ground recycled glass used as a silica source in geopolymer binders, improving sustainability and network connectivity.

References

1. Sodium aluminate activated waste glass: Reduced efflorescence behavior by C(N)−A−S−H transformation. Cement and Concrete Research (2024).
2. Extensive reuse of soda-lime waste glass in fly ash-based geopolymers. Construction and Building Materials (2018).
3. Fresh and mechanical properties overview of alkali-activated materials made with glass powder as precursor. Cleaner Materials (2022).