Compressive Performance of PVA Fiber-Reinforced 3D Concrete Printing Permanent Formwork Composite Columns Reinforced with BFRP-Bars (2024-10)¶

Among the reinforcement methods for 3D concrete printing (3DCP) structures, PVA fiber reinforcement and resetting the reinforcement cage after printing the permanent formwork are the preferred methods with a high degree of design flexibility and automation. These methods also eliminate the need for costly temporary formwork, which saves both manpower and materials. However, the former lacks reinforcement in directions perpendicular to the printing, while the latter steel bars are prone to corrosion. This paper proposes a hybrid approach: PVA fiber-reinforced 3D concrete printing permanent formwork composite columns reinforced with BFRP bars (3DPPFBRC). Compression tests and theoretical analysis were conducted to study compressive performance. Twelve short columns were designed and fabricated considering longitudinal reinforcement ratio (0.00%, 1.88%, 2.51%) and eccentricity (0.00%, 20.0%) as parameters. Visual observation was carried out using the digital image correlation (DIC) method. The experimental results indicated that the surface damage of the 3DPPFBRC was significantly lower than that of the BFRP bar-reinforced concrete column (CBRC). The PVA fiber-reinforced 3D concrete printing permanent formwork (3DPPF) contains a certain amount of PVA fibers, which provide stress-bridging to some extent, contribute to the circumferential confinement of the BFRP longitudinal bars and core concrete, enhance the load-bearing capacity and bending capacity of the concrete columns, and result in reduced lateral displacement. The BFRP longitudinal bars play a vital role in maintaining the ductility and the enhanced load-bearing capacity of the specimens. Based on the experimental results and current standards, the calculation models for both the axial and eccentric compression bearing capacities of 3DPPFBRC were proposed, and the calculation results agreed well with the experimental results. The results provide a theoretical and experimental foundation for the engineering application of 3DPPFBRC.