Molecular dynamics study on the influence of graphene oxide on the tensile behavior of calcium silicate hydrate composites

Abstract

By virtue of its great dispersibility, ultra-high specific surface area and superior mechanical properties, graphene oxide (GO) has been a potential candidate for nanoengineered concrete. A recent experimental study has provided nanoscale evidence for the improved nanomechanical performance of calcium silicate hydrate (C–S–H) with the addition of GO. The further numerical studies are needed to validated the exiting findings and revealed the underlying nanoscale reinforcing mechanisms. In this study, we investigate the mechanical characteristics of C–S–H/GO nanocomposites under tensile loading at the nanoscale via molecular dynamics simulation and reveal the reinforcing mechanisms of GO in C–S–H gel. The results show that only mixing 9 wt% of GO nanosheets to the C–S–H gel can effectively reinforce the ductility of the C–S–H by 83% and delay the failure of cement-based materials. Ensuring a sufficient proportion of GO is essential for its enhancement effect. Insufficient GO content would cause stress concentration in the C–S–H gel, failing to produce the reinforcement and weakening the performance of the cement-based materials. GO acts as two main roles in C–S–H/GO nanocomposites as bridging roles and embedded roles. The bridging GO can reinforce the ductility of the C–S–H gel under stretching and increase the energy required for the C–S–H/GO nanocomposites to break, while embedded GO may destroy the integrity of the C–S–H and cause adverse effects such as stress concentration. The findings of this work can promote understanding of the reinforcing mechanisms of GO in C–S–H composites and assist in balancing the reinforcing effects and the economic cost of GO application in practical engineering.