Snapshot on 3D printing with alternative binders and materials: Earth, geopolymers, gypsum and low carbon concrete

The rapid development of 3D concrete printing now offers mechanical efficiency and freedom to push the limits of construction design. The digital manufacturing process holds potential for reducing carbon footprints through design optimization. Printable concrete, which is a mix of cement (based on ordinary Portland cement), aggregates, and admixtures, is attractive due to widespread and cost-effective constituents. However, many common formulations omit gravel, requiring higher cement paste volumes and inducing significant embodied carbon. Assessing the potential of low-carbon cements like Limestone Calcined Clay Cement (LC3), calcium aluminate cement (CAC), or magnesium-based cement for 3D printing is a current challenge that can address this issue. Tailoring these construction materials to printing applications and environmental needs now drives scientific exploration. This paper comprehensively reviews alternative materials and binders such as earthen materials, geopolymers, low carbon binders or gypsum-based materials, addressing fresh and hardened properties, developed digital processes, targeted applications, and discussing advantages and drawbacks of each alternative.