Effects of the Combined Incorporation of Superabsorbent Polymers and Polyvinyl Alcohol Fibers on Material Properties of 3D Printable Mortar (2025-11)¶

This study examines the impact of incorporating superabsorbent polymers (SAPs) and polyvinyl alcohol (PVA) fibers on the material properties of 3D printable mortar. Key properties, including rheological behavior, setting time, green strength, plastic shrinkage, surface moisture, interlayer bonding, and anisotropy, were comprehensively evaluated. The results indicate that SAP released absorbed water before the material became stiff, thereby improving flowability and extending the open time. In contrast, PVA fibers increased both dynamic yield stress and plastic viscosity, which hindered pumpability. However, once the material stiffened, PVA fibers acted as physical bridges, enhancing buildability. During this phase, SAP delayed the initial and final setting times by 30 and 33 min, respectively, compared to the reference specimen. Following the printing process, both SAP and PVA fibers effectively mitigated plastic shrinkage cracking. SAP improved interlayer bonding by increasing and retaining surface moisture, resulting in a 9.1 % enhancement at 28 days with 0.5 % SAP by cement weight, while 0.4 % PVA fibers by total volume contributed a 5.3 % improvement through their bridging action across the interlayer interface. These effects mitigated the reduction in mechanical performance and anisotropy caused by interlayer interfaces. At 28 days, the incorporation of SAP and PVA fibers reduced the anisotropy coefficient by 27.3 % and 10.6 %, respectively, compared to the reference specimen. Notably, the combined incorporation of SAP and PVA fibers exhibited a combined effect, resulting in superior overall performance compared to individual use.