Increasing pollution poses enormous pressure on the global ecosystem, with a need to limit the carbon emissions from the construction materials industry. Mitigation of this carbon is possible by converting industrial wastes into alternative cement and optimisation in the building process. Taking this into account, advancement is taking place in sustainable geopolymer composites-based additive manufacturing (AM) technology. Typical precursors for geopolymer binder are industrial waste by-products (such as slag, fly ash, and metakaolin). In another aspect, AM entails several benefits such as easy fabrication, freedom of design, the ability to generate sophisticated structural elements and reduce: expenses, time, waste generation, and labor demands. This review journal paper on geopolymer AM presents a bibliometric study followed by an overview of AM methods and influencing parameters, techniques in geopolymer AM (such as extrusion and powder bed), materials, improvements in AM process, and fresh-state and hardened-state properties. Recent developments in AM processes within the geopolymer are critically discussed while investigating the properties and applications of the same. The discussion includes an analysis pinpointing research gaps essential in developing geopolymer AM. Graphical abstract

Geopolymer composites provide an environmentally friendly alternative to cement-based composites in the construction industry. Due to their distinctive material composition, geopolymers also exhibit electrically conductive properties, which permit their application as a functional material. The current work aims to study the distinctive electrical properties of fly-ash-based geopolymer composites. Varying dosages of graphene oxide (i.e., 0, 0.1, 0.2, 0.3, 0.4% (by wt. of binder)) were introduced into the geopolymer matrix to enhance electrical conductivity. While GO (graphene oxide) is typically less conductive, the interaction of GO sheets with the alkaline solution during geopolymerisation reduced the functional groups and produced cross-linked rGO (reduced graphene oxide) sheets with increased mechanical and electrical conductivity properties. Solid-state impedance spectroscopy was used to characterize the electrical properties of geopolymer composites in terms of several parameters, such as impedance, electrical conductivity and dielectric properties, within the frequency ranging from 10¹ to 10⁵ Hz. The relationship between the electrical properties and graphene oxide reinforcement can effectively establish geopolymer composite development as smart materials with desirable functionality. The results suggest an effective enhancement in electrical conductivity of up to 7.72 × 10⁻¹³ Ω⋅mm⁻¹ and the dielectric response performance of graphene-reinforced fly-ash-based geopolymer composites.