Anionic Biopolymers to Enhance Concrete Rheological Properties for 3D Printing Applications (2025-10)¶

This study investigates the use of various anionic biopolymers as admixtures to enhance the rheological properties of mixtures for 3D printing (3DP) applications. The investigated bio-based polymers include almond gum, tragacanth gum, welan gum, and giant kelp extract. The experimental program was conducted in two phases: (i) developing mixtures with tailored rheological properties by varying biopolymer type and dosage, and (ii) evaluating their 3DP performance through printing trials. Results showed that biopolymer incorporation significantly enhanced thixotropic behavior, increasing re-flocculation (Rthix) and flocculation (Athix) rates by up to 83 % compared to the reference mixture. These rheological improvements resulted into reduced deformation during printing, with diametrical variation (DV) decreasing by up to 76.1 %. Cross-sectional analysis showed a significant reduction in bottom-layer widening, with the deformation index (DI) reduced by 53.0 %–81.9 %. In terms of extrudability, biopolymer led to a 51.4 %–87.4 % reduction in the coefficient of variation (COV) of cross-sectional areas along the print path. Among the tested biopolymers, almond gum (1.0 %) and tragacanth gum (0.5 %), combined with optimized superplasticizer dosage, showed the best balance between flowability and buildability. Although giant kelp extract (1.0 %) offered superior dimensional stability, its high viscoplastic properties impeded extrusion. In contrast, welan gum (0.25 %) enhanced extrusion performance due to its lower viscoplastic properties, although this came at the expense of structural stability.