▎ 摘　　要

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.