Behavior of Hollow Glass Microsphere Aggregate Concrete Composite Short Columns with 3D-Printed Permanent Formwork Under Axial Load (2026-01)¶

This study investigates the axial compression performance of Hollow Glass Microsphere (HGM) aggregate concrete composite short columns with 3D-printed permanent formwork. The research parameters include the HGM replacement rate in the formwork (25%, 50%, and 75% volume replacement rates), the layer thickness of 3D-printed formwork (10 mm, 15 mm, and 20 mm), and the casting interval, defined as the time between formwork fabrication and casting of the inner concrete (1, 3, and 7 days). Test results show that the failure characteristics of composite concrete short columns are mainly formwork cracking and spalling, leading to a bearing capacity lower than that of cast short columns. The HGM replacement rate, formwork thickness, and casting interval were found to significantly affect the interfacial bond strength between the formwork and the cast concrete, which in turn influenced the load-bearing contribution of the formwork at peak axial load. Among the tested specimens, composite short columns with a 25% HGM replacement rate, 15 mm formwork thickness, and a 7-day casting interval demonstrated the highest axial compressive bearing capacity. Finally, a design method for predicting the bearing capacity of composite concrete short columns is proposed. The average ratio between the theoretical calculation results and the test results is 1.02, which verifies the accuracy and reliability of the proposed method.