The influence of graphene derivatives on the mechanical and durability properties of conventional and geopolymer concrete

Graphene derivatives, particularly graphene oxide (GO) and graphene nanoplatelets (GNP), have emerged as promising nanoscale additives for enhancing mechanical properties and durability of concretes based on ordinary Portland cement (OPC) and alkali-activated binders (AAB). Due to their high specific surface area, high aspect ratio, and strong interfacial reactivity, these materials modify cementitious matrices at the nanoscale, leading to refined microstructures and improved load transfer when incorporated at appropriate dosages. This review critically examines the influence of GO and GNP on conventional OPC-based and AAB-based concretes, with emphasis on graphene concentration, dispersion techniques, surfactant selection, and ultrasonication parameters, as well as the underlying reinforcement mechanisms. Microstructural observations synthesized in this review indicate that GO and GNP enhance composite performance through interfacial bonding with hydration or geopolymer gels, nucleation-induced pore refinement, and crack bridging and pinning mechanisms. Studies reported improvements in compressive, splitting tensile, and flexural strengths when an optimum graphene content is added to the mix. Graphene dosages exceeding the system-specific optimum, or inadequate dispersion led to agglomeration of graphene derivatives and reduced performance of cementitious composites. This review addresses the optimal dosages of GO and GNP for enhancing the performance of OPC- and AAB-based concretes.