Performance evaluation of cementitious composites by designing an extrusion system for construction 3D printing

The advancement of construction 3D printing (C3DP) relies heavily on optimizing the material formulation and hardware configuration. This study reports the development of a customized extrusion system—comprising a hopper, auger, and interchangeable nozzles— designed for use with locally sourced, cost-effective cementitious composites. A series of composite mixes were evaluated, with the CSSAW mix (cement, fine sand, fine soil, admixture, and water) exhibiting superior printability, achieving a slump height of 27 cm after 30 min and maintaining structural integrity across 11 printed layers. Compared to the baseline CSW mix, CSSAW showed a 92.8% improvement in flowability and a threefold enhancement in shape retention. Optimization of printing parameters, including a speed of 25 mm/s and layer height of 10 mm, further improved interlayer adhesion and surface quality. The rectangular nozzle was found to enhance deposition consistency and print stability. The findings establish a practical framework for deploying C3DP in real-world construction setups using sustainable materials and scalable extrusion systems.