Improving flexural strength of UHPC with sustainably synthesized graphene oxide

Abstract Ultrahigh-performance concrete (UHPC) has been increasingly employed for infrastructure and building structure, thanks to its excellent durability and exceptional mechanical properties; however, improving its relatively low flexural strength remains a challenging issue. This study presents an experimental investigation on improving the compressive strength and flexural strength of UHPC by employing sustainably synthesized graphene oxide (GO). The content of micro steel fibers (MSFs) for the UHPC ranges from 0.5 to 1.5% by volume of concrete. For each level of MSFs addition, the dosage of GO added is from 0.00 to 0.03% by mass of cement. The results indicate that the electrochemical (EC) method to synthesize GO is greener, safer, and lower in cost for construction industry. And the compressive strength of UHPC is slightly improved, while its flexural strength is significantly increased from 33 to 65%, demonstrating that the incorporation of GO can be an effective measure to enhance the flexural strength of UHPC under standard curing and steam curing. This can be associated with the improvement in bond strength between the MSFs and the matrix contributed by the improved interfacial microstructure, the higher friction increase, and the mechanical interlock at the interface between the MSFs and the bulk matrix, thanks to the addition of GO.