Integrating Prestress into 3D Printed Ultra-High Performance Concrete Composite Beams for Superior Flexural Performance (2025-09)¶

The high-performance flexural capacity of 3D printed concrete structures (3DPS) without steel reinforcement cages has become a central focus in construction 3D printing technology. Previous studies have found that combining 3D printed ultra-high performance concrete (3DP-UHPC) skeletons with single steel bars is an effective alternative method to traditional reinforcement cages. To further enhance the flexural capacity of 3DPS, this study proposes a form-force coupling method using 3DP-UHPC skeletons and prestressing to enhance cage-free 3D printed structures. The bending performance of prestressed 3D printed concrete composite beams (P-CRC) is evaluated. Key assessments include monitoring the prestress tensioning process, measuring short-term prestress loss, and analyzing the cracking load, ultimate load-bearing capacity, failure modes, and strain of P-CRC beams. Results show that P-CRC beams exhibit significantly superior performance compared to reinforced concrete beam. Their cracking load is nearly 6 times higher than that of RC beam, and it approaches the ultimate load of reinforced concrete beam. The ultimate load-bearing capacity is increased by approximately 40 %, while flexural toughness is enhanced fivefold. These findings provide valuable experimental data and theoretical support for the broader adoption of 3D concrete printing, particularly in large-span applications.