Effect of Superabsorbent Polymer on 3D Printing Characteristics as Rheology-Modified-Agent (2024-06)¶

This study aims to investigate the effects of two superabsorbent polymer (SAP) types, S1 and S2 (with continual absorption and rapid desorption, respectively) as rheology-modified agent on 3D printing characteristics. Three base mixtures were selected with different thixotropic behaviors (i.e., mixtures with high re-flocculation (τfloc), high structuration rate (Athix), and both low τfloc and Athix, respectively). The initial mini-slump flow of 190±10 mm was secured by adjusting superplasticizer (SP) or water demand (increasing w/b by either 0.025 or 0.05). An extrudable region was determined within the range of τfloc (200–890 Pa) and Athix (15–60 Pa/min). The use of the S2 SAP significantly improved extruded performance for mixtures with τfloc higher than 1000 Pa. The use of the S1 SAP without increasing w/b (only with extra SP demand) significantly improved the resistance against plastic collapse for the mixtures with τfloc lower than 300 Pa. The reduction in 28-day compressive strength for printed specimens was correlated with τfloc. A high τfloc value led to inadequate interlayer bond and an increased propensity for surface defects of printed structure. The S2 SAP acted as a rheology-modified agent to reduce τfloc and improved the interlayer bond performance by 10 %-20 %.