Bond behavior between steel and solid waste concrete activated by soda residue and carbide slag in concrete-filled steel tubes (CFSTs)

In recent years, the increasing emphasis on sustainable development in civil engineering has significantly advanced research on solid waste materials. However, the practical application of these materials in structural engineering remains limited. This paper explores the application of solid waste concrete (SWC) incorporating a cementitious material composed of granulated blast furnace slag (GBFS) activated by soda residue (SR) and carbide slag (CS) in concrete-filled steel tubes (CFSTs), focusing on the bond behavior between the steel tube and concrete. Firstly, concrete specimens with varying strength grades and replacement rates of solid waste cementitious material ( ρ sw ) were prepared, and their mechanical properties were investigated. Then, the corrosion issues arising from the use of SWC in CFST were discussed, with a detailed examination of the corrosion characteristics on the inner surface of the steel tube. Finally, the bond behavior such as the failure mode, load-slip curve, bond strength, stiffness and strain distribution of solid waste concrete-filled steel tube (SWC-FST) under repeated push-out tests were explored. The results demonstrated that incorporating solid waste cementitious materials could reduce the strength of concrete and cause significant corrosion on the inner surface of the steel tube, leading to a notable increase in the bond strength between the steel tube and concrete, along with complex variations in stiffness.