Material and Structural Fatigue-Performance of 18m Span Reinforced Arch Structure Manufactured by 3D Printing Concrete as Permanent Formwork (2025-01)¶

This paper proposes a rapid construction method using 3D printed concrete as permanent formwork followed by conventional reinforcement installation and cast-in-place concrete, which has been successfully applied to the real practice of 3D printing bridge in China. In this paper, a basalt fiber reinforced cementitious composite was prepared for 3D printing large-scale formwork. The printable and mechanical properties of the basalt fiber reinforced 3D printing materials were systematically investigated and the requirement for formwork application had been met. Meanwhile, the effect of interlayer on long-term durability, e.g, the carbonation and frost resistances of the 3D printed concrete formwork were investigated through accelerated carbonation and freezethaw cycles tests. The interlayer regions perform 326 % larger carbonation depth than filaments matrix. The 3D printed specimens show 147 % higher weight loss ratio at 200 freeze-thaw cycles compared to cast ones. Additionally, the optimized 3D printed concrete was adopted for the manufacturing of largescale reinforced arch structures with a net span of 18 m. To evaluate the structural integrity of reinforced arch structure with 3D printed concrete formwork, fatigue testing with 2 million cycles at 40 %–60 % of the design load capacity was performed. Experimental investigations validated the favorable bonding of the 3D printed formwork. The construction practice of 3D printed arch structure for bridge project was illustrated.