Effect of steel slag on the mechanical properties and self-sensing capability of ultra-high performance concrete (UHPC)

Abstract

This study investigates the self-sensing capability and mechanical properties of ultra-high performance concrete (UHPC) incorporating steel slag aggregates. The experimental findings underscore the potential of steel slag as a promising industrial by-product capable of fully replacing the natural fine aggregates within UHPC. In addition, the incorporation of steel slag is shown to reduce CO2 emissions by approximately 40 kg/m3, as determined through life cycle assessment software, while simultaneously enhancing flowability when compared to UHPC incorporating natural aggregate. Although the compressive and tensile strength of UHPC with steel slag is slightly lower than that of UHPC with natural aggregates, it still demonstrates impressive performance, with compressive and tensile strengths reaching approximately 207 MPa and 14 MPa, respectively. To assess the mechanical properties and self-sensing capacity of steel slag, this study incorporates carbon fiber and multiwalled carbon nanotubes (MWCNT) into the UHPC series. The self-sensing capacity results emphasize the advantage of incorporating steel slag due to its high iron content that leads to superior conductivity compared to silica sand. Furthermore, comparisons are made with UHPC series incorporating carbon fiber and MWCNT. UHPC with steel slag demonstrates superior self-sensing capabilities compared to the silica sand series with carbon fibers, and it is comparable to UHPC with MWCNT. To quantify the self-sensing capability of UHPC with steel slag, nonlinear curve fitting is employed, resulting in highly accurate simulation outcomes. These experiments collectively highlight the multifaceted benefits of utilizing steel slag aggregate in UHPC, encompassing environmental advantages, enhanced flowability, and impressive self-sensing capabilities.