Quasi-static and Dynamic Mechanical Properties of Recycled Aggregate Concrete-Filled Steel Tube Columns Exposed to High Temperature

Developing recycled aggregate concrete (RAC) offers an effective means of disposing of Construction and Demolition waste (C&DW) while also conserving natural aggregate resources. Despite the clear environmental benefits, RAC is not commonly utilized due to its relatively inferior performance. A promising solution is to develop RAC-based composite components such as recycled aggregate concrete-filled steel tube columns (RACFST). To facilitate the practical application of RACFST where complex load cases are possible, this study investigates the performance of high temperatures damaged RACFST under increased load strain rates via split Hopkinson pressure bar (SHPB) impact tests and numerical simulation. Besides, the influences of various material parameters were analysed to explore optimal design methods for RACFST. Results indicated satisfactory performance of RACFST. The lowest strength ratio of RACFST to normal aggregate concrete-filled steel tube columns still reaches 0.88 (quasi-static, after 700 °C). Simulation research indicated that steel ratio is a more important factor than the strength of steel and RAC in enhancing impact properties. This study further revealed the potential of using RACFST to promote the recycling and application of RAC and create circular economy for sustainable infrastructure development.