Study on the compression performance of 3D printing concrete permanent formwork composite columns

3D printing concrete technology is increasingly being utilized in the construction industry as an advanced manufacturing method. To study the compressive performance of 3D printing concrete permanent formwork composite columns, both axial and eccentric compression tests were conducted. Through comparative analysis between composite columns and cast-in-place columns, the effects of the longitudinal reinforcement ratio on failure modes, load-displacement curves, loadlongitudinal reinforcement strain curves, concrete strain distributions in the center section, and ultimate load-bearing capacity were examined. The results showed that the 3D printing concrete permanent formwork exhibited good overall integrity with the core concrete, with no debonding occurring before failure, thus offering a viable replacement for traditional formwork. Under axial and eccentric compression, the load-bearing capacity of the 3D printing composite columns was superior to that of the cast-in-place columns. Specifically, excluding the eccentrically loaded column with a reinforcement ratio of 1.88 %, the load-bearing capacity of other 3D printing concrete permanent formwork composite columns improved by more than 11 % compared to traditional concrete columns. Based on the calculation formula for the load-bearing capacity of cast-in-place reinforced concrete, a formula for the compressive load-bearing capacity of the 3D printing composite columns was derived. This formula showed good agreement with the experimental results, providing a solid foundation for the future application of 3D printing concrete permanent formwork composite columns in practical engineering.