Bond behaviour of expansive self-compacting concrete infilled light gauge steel rectangular columns

This research paper explores the bond strength and bond behaviour of expansive self-compacting concrete (SCC) infilled rectangular light gauge steel tube columns. A total of eighteen specimens were tested to assess the ultimate bond strength with various parameters for the investigation: (a) steel tube thickness (2 mm, 3 mm, 4 mm); (b) infilled concrete type (SCC and expansive SCC); (c) concrete strength grade (M30,M40,M50). The findings illustrated that the thickness of the steel tube and concrete strength has a significant impact on the bonding strength of rectangular filled steel tube columns. The measured self-stresses of expansive SCC range from 2.26 to 5.05 MPa, relies on steel tube thickness and concrete strength. Furthermore, the experimental results indicate that incorporating expansive cement in SCC has yielded favorable benefits by enhancing the shear strength in the range of 30.4–37.5% along with delayed bond failure compared to SCC counterparts. The experimental findings suggest that the bond strength increases as the width-to-thickness (B/t) ratio decreases. This implies that a thicker wall tube provides better confinement and interaction with the concrete infill, leading to enhanced performance. This paper also emphasizes the bond transfer mechanism with various parameters on bonding strength (τ_u) during different loading stages. The inclusion of expansive cement in SCC not only improves the interfacial bonding between steel and concrete but also minimizes the consumption of Portland cement, thereby mitigating the carbon footprint.