Influence of different types of superabsorbent polymers on fresh mechanical properties and interlayer adhesion of 3D printed concrete

3D printed concrete (3DPC) is an essential technology for achieving efficient, precise, and sustainable construction. Nevertheless, due to limitations in materials and processes, 3DPC is prone to insufficient green strength and weakness in the interlayer area, which can result in print collapse and diminish its interlayer adhesion strength. Therefore, understanding green strength and interlayer adhesion strength of 3DPC is crucial for ensuring its structural safety. Superabsorbent polymer (SAP) serves as a novel type of concrete admixture, demonstrating the potential to promote green strength development and augment interlayer adhesion properties by facilitating the hydration process through water absorption and release. This study presents the first investigation into the effects of two commercially available SAPs on green strength and interlayer adhesion of 3D printed concrete. The role of SAP in improving interlayer adhesion performance in 3DPC is further elucidated through X-ray diffraction (XRD), Scanning electron microscopy (SEM). The results indicate that, compared to the control group, in the absence of added compensated water to SA1, the compressive strength at 15 min and splitting tensile strength of the printed specimen at 28 d increased by 282 % and 24.9 %, respectively, whereas SA2 demonstrates a relatively weaker enhancement effect. This study demonstrates that SAP promotes structural accumulation during the 3DPC printing stage, thereby presenting itself as a favorable material choice for applications involving 3DPC.