Axial compression behavior and stress–strain relationship of slurry-wrapping treatment recycled aggregate concrete-filled steel tube short columns

Abstract

Abstract The utilization of recycled concrete can effectively solve the problems of large accumulations of construction waste and the constant consumption of natural aggregates. Slurry-wrapping modification and concrete-filled steel tubes (CFSTs) are effective approaches to enhance the utilization ratio of recycled concrete. The study involved 4 ordinary CFST columns and 16 slurry-wrapping recycled aggregate concrete-filled steel tube (SRACFST) columns. The variable parameters included the slurry-wrapping recycled aggregate replacement ratio and the section form. The result shows that the ultimate strength of the specimens reached the minimum and maximum at 25 and 100% aggregate replacement ratio. The favorable strength performance of the SRACFST columns is attributed to the dominant positive effect of the slurry-wrapping treatment in reducing matrix porosity over the negative impact of the recycled aggregate’s complex interface transition zone. Due to the hoop factor, the residual bearing ratio peaks at a 25% substitution ratio. Four design standards were used to predict the ultimate strength, with GB50936 and EC4 yielding more accurate estimations, while AISC360-10 and AIJ provided conservative estimations. This study presents the equations of the stress–strain curve for the whole axial compression process, which can be directly applied in the theoretical and numerical analysis of RACFST columns.