Deposition of Graphene Oxide on Steel Fiber Surface for Enhanced Mechanical Properties of Ultrahigh-Performance Concrete

Abstract This study aims to enhance ultrahigh performance concrete (UHPC) by modifying steel fibers with graphene oxide (GO). The electrophoretic deposition (EPD) method was employed to coat GO onto steel fiber surfaces, with investigations focused on GO modification effects on fiber-matrix interfacial properties and UHPC mechanical performance. The results demonstrate that GO deposition significantly improves fiber-matrix interface properties. The 30-min EPD treatment increased the average interfacial bonding strength and equivalent bonding strength by 22.1% and 11.1%, respectively. Given the enhancement of interface shear stress, the failure plane shifted toward the matrix side, whereas periodic groove structures formed along the inner walls of pulled-out fiber channels. This phenomenon is attributed to the physical-chemical synergistic interface strengthening arising from the rough surface morphology of GO coating and the chemical bonding with hydration products. Benefiting from the improved interface properties, GO-modified steel fibers enhanced the tensile strength ( σ p c ), tensile energy absorption capacity ( g - value ), and flexural strength of UHPC by 8.5%–17.6%, 28.8%–75.0%, and 27.6%–38.9%, respectively. Due to the declining nanoparticle deposition efficiency caused by long-term EPD treatment, the performance enhancements exhibited a nonlinear decay pattern with extended EPD treatment duration.