Influence of process parameters on 3D concrete printing: A step towards standardized approaches

3D concrete printing (3DCP) is an innovative technology driving automation in the construction industry. This technology holds the potential to reduce carbon footprint, construction costs, and waste through the careful selection of materials and process parameters. While recent studies have extensively focused on material selection for 3DCP, the influence of process parameters is often overlooked, resulting in performance variations. Different printing scenarios yield varying outcomes, even with the same mix design, underscoring the need to tailor process parameters for optimal compatibility. This paper addresses critical gaps by analyzing seven key process parameters: nozzle shape, nozzle size, nozzle standoff distance, printing speed, extrusion rate, interlayer interval time, and surface dehydration, and their effects on fresh and hardened properties. The paper's significance lies in its synthesis of quantitative findings and practical guidelines for optimizing these parameters. The use of square or rectangular nozzles boosts compressive strength by 43% and flexural strength by 28% compared to circular ones. Optimal nozzle size requires a critical ratio of at least 4. For strong interlayer bonding, the standoff distance should be less than the nozzle opening. The synchronization of printing speed and extrusion rate is crucial and should be calibrated according to the material's yield stress. Finally, maintaining ambient conditions, 20-25°C, 80-100% relative humidity, and wind speeds under 3 m/s, is essential to prevent surface dehydration. By providing application-specific recommendations and empirical formulas, this paper offers a comprehensive guide for tailoring process parameters to various printing scenarios.