Additive manufacturing of geopolymer composites for sustainable construction: critical factors, advancements, challenges, and future directions

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.