The development of concrete filled steel tube with enhanced performance via the use of expansive ultra high performance concrete

Abstract

The combination of ultra high performance concrete (UHPC) and steel tube is expected to create a concrete filled steel tube (CFST) with improved performance, meeting the increasing demands of high-rise buildings and long-span structures. However, UHPC suffers from high autogenous shrinkage, limiting the synergistic effects. Herein, we firstly prepared expansive UHPC with the combined use of high titanium heavy slag sand (HTHSS) serving as internal curing agent and MgO-based expansive agent (EA). After that, we systematically evaluated the volume stability and strength development of the expansive UHPC, where the results indicated that the addition of HTHSS could not only reduce autogenous shrinkage via humidity compensation but also provide water for the expansion reaction and enhance the efficiency of the expansion agent (EA), thus improving the volume stability of UHPC. After that, CFST with the expansive UHPC has been developed and the axial load-displacement curves showed a notable enhancement. Specifically, the peak bearing capacity of expansive UHPC concrete filled steel tube contributed to a 19% strength boost compared to that of CFST with traditional UHPC. This improvement was also evident in the stress-strain curves, as the peak stress of the expansive UHPC concrete filled steel tube was approximately 170 MPa, about 21% higher than that of traditional UHPC filled steel tube. This study provides a superior construction material, offering a valuable material choice for the development of the construction industry.