Unveiling additive effects in 3D printed geopolymer composites: A multi-scale analysis coupling rheological insights and CFD-optimized deposition

This study optimizes 3D printing parameters for geopolymer composites by implementing rheological characterization in Computational Fluid Dynamics (CFD) modeling. Geopolymer formulations with PEG4000, sepiolite, and xanthan gum were analyzed for viscosity, shear-thinning behavior, and viscoelastic properties. Xanthan gum demonstrated the best rheological performance, providing high viscosity, strong shear-thinning behavior, and rapid recovery, making it the optimal additive for 3D printing. Using real experimental data, a CFD model was developed to simulate deposition, capturing the materials’ non-Newtonian and viscoelastic behavior. Key printing parameters, such as substrate velocity and nozzle-to-substrate gap, were optimized to achieve accurate strand morphology. The model was validated by comparing printed strands with simulation ones, yielding a low error of 5%. This work represents the first CFD simulation of geopolymer 3D printing, offering a predictive framework for reducing material waste and improving print quality.