Limestone–Calcined Clay (2026-01)¶

Additive manufacturing in construction has emerged as a promising alternative to conventional form-work-based building processes. However, most printable mixtures are rich in ordinary Portland cement OPC, which is associated with high embodied carbon and energy consumption. Active 3D concrete printing researchers are exploring limestone-based binders, specifically Limestone–Calcined Clay Cement LC3, as substitutes to OPC for a low carbon footprint. This literature review summarises recent research on LC3 as a low-carbon binder for 3D printing. Primary sources show calcined clay improves static and dynamic yield stress and buildability but reduces flowability, while limestone filler acts as a fine filler, improving particle packing and early-age hydration. Optimised LC3 mixtures achieve high yield stress and thixotropy that enable the printing of up to 23 layers while keeping good pumpability and extrudability. Fibre reinforcement increases 28-day compressive and flexural strength without clogging the nozzle. Studies report that LC3-based concretes can attain 28-day compressive strengths of 30–50 MPa while achieving up to 30–50 % reductions in CO2 emissions relative to OPC. This review discusses rheological behaviour, mechanical properties, sustainability benefits, and mixture-optimization strategies of LC3, also pointing out research gaps and future directions for climate-positive 3D printing.