Molecular dynamics simulation and experimental study on mechanical properties and microstructure of cement-based composites enhanced by graphene oxide and graphene

Graphene-based materials have been considered as reinforcement for cement-based materials due to its excellent properties. In this paper, the effects of graphene oxide (GO) and graphene nanoplatelets (GNPs) on the mechanical properties and microstructure of cement-based composites are investigated. The results reveal that the incorporation of 0.02 wt% GO and GNPs can enhance the flexural strength by 16.3% and 11.6%, respectively. In addition, GO and GNPs can fill the cracks and form a compacted microstructure in cement mortars. Furthermore, the enhanced mechanism of calcium silicate hydrate composite (C–S–H), which is the main production of cement hydration, is studied by reaction molecular dynamics. The results from simulation show that Young's modulus and tensile strength of C–S–H are enhanced by 32.1% and 23.8% with the incorporation of GO, because the hydrogen-bonds (H-bonds) linkages and Ca2+ near the interface surface play an important role to improve the interface adhesion and transfer more loads between GO and C–S–H. Comparatively, the graphene nanosheet unremarkable enhances the mechanical behaviour of C–S–H composite due to poor binding in the interlayer region.