Geopolymers: from origins to advanced applications of sustainable and adaptive materials

With the increasing urgency to reduce greenhouse gas emissions, geopolymers and alkali-activated materials (AAMs) present a low-carbon alternative to traditional cement-based construction materials. The production of standard cement contributes to 5-7% of global CO₂ emissions, so finding sustainable substitutes is crucial. Geopolymers, derived from aluminosilicate sources such as fly ash and metakaolin, are created through alkaline activation, forming a stable three-dimensional structure that offers durability and resilience. Similarly, AAMs are synthesized by activating calcium-rich materials in highly alkaline conditions, forming compounds like C-S-H gels that provide structural integrity. These materials demonstrate potential in a range of construction applications, including building restoration, fire-resistant materials, and environmental remediation. Geopolymers are especially promising for cultural heritage restoration due to their ceramic-like structure, durability, and compatibility with traditional materials. Despite their benefits, challenges remain, such as controlling the setting time, ensuring consistent precursor supply, and managing their behaviour in fresh states. Standardization is progressing, with several countries developing guidelines to support their use in infrastructure projects. Overall, geopolymers and AAMs are seen as viable paths toward sustainable building practices, though further research is needed for broader application.