experimental behaviour of recycled aggregate concrete-filled steel tubes under axial loading

This study experimentally explores the behaviour of recycled aggregate concrete-filled steel tubes (racfst) subjected to axial compression loading. twenty-four racfst specimens were tested to failure. for comparison purpose, tests were also performed on 12 normal concrete-filled steel tube (ncfst) specimens, three steel tubes and one specimen of recycled aggregate concrete. obtained results showed that the racfst demonstrates distinct mechanical properties, such as much higher strength, avoiding early buckling of steel and spalling of concrete, in comparison to steel tube and recycled aggregate concrete. this result from mutually beneficial interaction between the steel tube and concrete. more importantly, in comparison to ncfst, racfst exhibited marginally lower mechanical properties, similar scatter at peak stress and yet lower degradation after peak stress. quantitative details of these comparisons are reported in the current paper, providing insightful information on the potential use of racfst.